ALBERT

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Maryam Mohammadi, Esmaeil Poursaeidi, Kaveh Torkashvand〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present study provides a numerical simulation of the interface crack development in thermal barrier coatings, deposited using plasma spray method. The proposed model benefited from the SEM image obtained from our previous experimental studies so that the geometry was placed in a model with the dimensions of the tested specimens. In this study, the longitudinal and lateral growth effects of TGO, the creep effect of all coating layers, and the effect of thermal mismatch between layers were investigated on the stress distribution of the coating. The results obtained from previous experimental observations revealed that the separation occurs in the TC/TGO interface. Therefore, in the numerical study, it was defined as the cohesive layer. The separation of cohesive layer in various thermal ageing periods was further explored alongside the cooling-heating thermal cycles. The results obtained by the finite element analysis indicated that as the thermal ageing period increased, the interface separation was enlarged and cracks started to nucleate from other points of the interface. Separation behavior of TC/TGO interface was evaluated once increasing ageing period and thermal cycles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 374〈/p〉 〈p〉Author(s): H. Tian, K. Zhou, Y.C. Zou, H. Cai, Y.M. Wang, J.H. Ouyang, X.W. Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The aluminide coating was prepared on Ti-6Al-2Zr-1Mo-1 V titanium alloy by pack cementation to enhance the high temperature oxidation resistance for aircraft and aerospace applications. High temperature oxidation behaviors of packing cementation coated and uncoated titanium alloy samples were comparatively investigated by isothermal oxidation at 800 °C and 900 °C in air. The results show that the compact coating with about 60 μm thick was composed of TiAl〈sub〉3〈/sub〉. With isothermal oxidation for 100 h at 800 and 900 °C, the weight gains of the coated samples are 1.29 mg·cm〈sup〉−2〈/sup〉 and 4.06 mg·cm〈sup〉−2〈/sup〉 respectively, which are about 2/5 and 1/5 of that of titanium alloy substrates (3.20 mg·cm〈sup〉−2〈/sup〉 and 20.33 mg·cm〈sup〉−2〈/sup〉). The excellent oxidation resistance performance is attributed to the formation of a continuous and dense Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 layer on the TiAl〈sub〉3〈/sub〉 coating surface, which was effective to prevent the O element diffusing into the coating and then reduce the oxidation rate.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 September 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 374〈/p〉 〈p〉Author(s): Marzieh Mardali, Hamidreza Salimijazi, Fathallah Karimzadeh, Berengere Luthringer-Feyerabend〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lightweight magnesium alloys are currently being investigated as implants due to their biodegradability and mechanical properties. However, their clinical applications are limited by their high corrosion rate in the physiological environment. Coating Mg-based alloys is an approach that is used to delay primary corrosion and increase their lifetime. Therefore, hydroxyapatite was coated on anodized and non-anodized magnesium substrates using high-velocity oxy-fuel spraying. This study aimed to evaluate the effect of the MgO intermediate layer between the hydroxyapatite coating and Mg alloy substrate. The microstructure and corrosion behaviour of the coated samples are the main focuses of this study. X-ray diffraction spectroscopy was used to analyse the phases. Electrochemical impedance spectroscopy was performed in simulated body fluid. The results revealed that the presence of an anodized layer increased corrosion resistance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): L.A. Ardila-Rodríguez, B.R.C. Menezes, L.A. Pereira, R.J. Takahashi, A.C. Oliveira, D.N. Travessa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon nanotubes (CNTs) could be an excellent reinforcement for metal matrix composites, specifically for composites with aluminum or aluminum alloy matrix. Surface modification to improve hardness and other material properties has been performed by laser surface melting (LSM) process, where the laser beam melts the substrate together with alloying elements or reinforcing phase additives. In this work, Multiwalled CNTs (MWCNTs) were mixed by the electrostatic adsorption process with aluminum powder and the resulting mixed powder was laser melted on the surface of a 6061-aluminum alloy substrate. As a result, a modified substrate surface has been obtained from the Al/MWCNT – substrate co-melting, dilution and re-solidification processes. This modified layer was obtained by different LSM parameters and were characterized by Optical (OM) and Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDS), Field Emission Gun Scanning Electron Microscopy (FEG-SEM), X-Ray Diffraction (XRD) and Raman Spectroscopy (RS). The resulting mechanical behavior was evaluated by Vickers microhardness tests. The results showed that the presence of MWCNT in the aluminum powder improves the laser energy absorption, leading to the formation of a deeper modified layer, with segregation of Si particles homogeneously dispersed and improving the hardness. The formation of Al〈sub〉4〈/sub〉C〈sub〉3〈/sub〉 was not observed, evidencing that the MWCNTs did not react with the molten Al matrix during the LSM process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Jo Sharp, Itzel Castillo Müller, Paranjayee Mandal, Ali Abbas, Magnus Nord, Alastair Doye, Arutiun Ehiasarian, Papken Hovsepian, Ian MacLaren, W. Mark Rainforth〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Thin films of C/Mo/W deposited using combined UBM/HIPIMS sputtering show 2–8 nm clusters of material richer in Mo and W than the matrix (found by EDS microanalysis), with structures that resemble graphitic onions with the metal atoms arranged regularly within them. EELS microanalysis showed the clusters to be rich in W and Mo.〈/p〉 〈p〉As the time averaged power used in the pulsed HIPIMS magnetron was increased, the clusters became more defined, larger, and arranged into layers with amorphous matrix between them. Films deposited with average HIPIMS powers of 4 kW and 6 kW also showed a periodic modulation of the cluster density within the finer layers giving secondary, wider stripes in TEM. By analysing the ratio between the finer and coarser layers, it was found that this meta-layering is related to the substrate rotation in the deposition chamber but in a non-straightforward way. Reasons for this are proposed. The detailed structure of the clusters remains unknown and is the subject of further work.〈/p〉 〈p〉Fluctuation electron microscopy results indicated the presence of crystal planes with the graphite interlayer spacing, crystal planes in hexagonal WC perpendicular to the basal plane, and some plane spacings found in Mo〈sub〉2〈/sub〉C. Other peaks in the FEM results suggested symmetry-related starting points for future determination of the structure of the clusters.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): H. Raghuram, C. Katsich, K. Pichelbauer, K. Koschatzky, C. Gachot, U. Cihak-Bayr〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Friction and wear can cause severe surface damage of machine elements and result in their complete failure. Of the several ways to limit/control friction and wear, a measure to counter the potential damage is to apply a layer of a material with more desirable surface properties, which also provides the flexibility to use cost-efficient bulk materials. In systems under dry sliding conditions, such as railway switches, replacing the components cost considerable time and money. In the current study, laser cladding, a well-known powerful process for repair engineering, was used to fabricate new innovative low friction materials for dry sliding contacts that are exposed to corrosive attacks. The successful implementation of graphite as a solid lubricant in dry sliding conditions is well-known. A homogenous coating with an austenitic FeNi-based alloy containing different percentages of graphite was applied by means of laser cladding using preplaced powder method. The effect of graphite content and its lateral distribution on the friction and wear properties is investigated using a modified ASTM 〈a href="http://www.astm.org/Standards/G65" target="_blank"〉G65〈/a〉 test rig in two-body sliding configuration. Tribological results showed that increasing graphite content in the clads significantly reduces wear, but the level of the coefficient of friction appears to be determined mainly by the composition of the matrix. The wear resistance can be further increased by maximising the inter-particle distances. On the whole, clads of all compositions had superior wear resistance compared to reference materials such as stainless steel XNi22 and cast iron GJL250. The clads were further classified in terms of corrosion resistance against synthetic sea water in a modified potentiodynamic setup. The resistance to wear and corrosion improve with graphite content.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219308692-ga1.jpg" width="355" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Yu-Siang Fang, Kun-An Chiu, Hien Do, Li Chang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Highly oriented cubic (100) HfN films were grown on Si (100) substrates by direct current magnetron reactive sputtering of a metallic Hf target in an Ar/N〈sub〉2〈/sub〉 gas environment. The influence of N〈sub〉2〈/sub〉 flow ratio on the (100) preferred orientation and crystallinity of the HfN films is investigated. X-ray diffraction shows that not only HfN but also orthorhombic HfSi〈sub〉2〈/sub〉 forms in the sputtered films. Increasing the N〈sub〉2〈/sub〉 flow ratio is unfavorable for the formation of HfSi〈sub〉2〈/sub〉 while the deposition rate of HfN is decreased. X-ray diffraction and cross-sectional scanning transmission electron microscopy (STEM) reveal that epitaxial orthorhombic HfSi〈sub〉2〈/sub〉 can form on the Si substrate, and (100) HfN is in epitaxy with the epitaxial HfSi〈sub〉2〈/sub〉. As a result, a (100) oriented HfN film can grow on Si. The epitaxial relationships are shown to be HfN (100)[01〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈/math〉] // HfSi〈sub〉2〈/sub〉 (020)[001] // Si (100)[01〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈/math〉] and HfN (100)[01〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈/math〉] // HfSi〈sub〉2〈/sub〉 (020)[100] // Si (100)[01〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg"〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈/math〉]. Atomically resolved STEM images also show the bonding characteristics across the HfN/HfSi〈sub〉2〈/sub〉 and HfSi〈sub〉2〈/sub〉/Si interfaces.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): İlyas Türkmen, Emre Yalamaç, Mourad Keddam〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, a substitute boriding powder including boric acid as boron source was prepared and employed for boronizing of SAE 1020 steel. The boronizing processes were performed at 850, 900 and 950 °C for 4, 8 and 12 h. The formed boride layers were identified by varied experimental methods such as optical microscope, SEM and WDS analysis. As an outcome of the analyses, the boride layer containing only Fe〈sub〉2〈/sub〉B phase with saw-tooth morphology was specified on surface of the samples. A diffusion model was proposed to estimate the coefficients of boron diffusion in the Fe〈sub〉2〈/sub〉B layers. The value of boron activation energy for SAE 1020 steel was calculated as 183.14 kJ/mol and the result was contrasted with literature data. As a result of the microhardness measurements, the average hardness value of Fe〈sub〉2〈/sub〉B layer was about between 1200 and 2000 HV〈sub〉0.1〈/sub〉. The average hardness values of the transition zone and matrix zone were determined to be approximately 160 HV〈sub〉0.1〈/sub〉 and 151 HV〈sub〉0.1〈/sub〉, respectively. This study mainly concentrates on the tribological properties of borided SAE 1020 steel with using alternative boriding powder. Coefficient of friction graph was drawn for each sample and the wear rates were calculated. It was specified that specific wear rate of borided samples was roughly 47 times lower than that of unborided samples.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): O.Yu. Goncharov, I.V. Sapegina, R.R. Faizullin, L.Kh. Baldaev〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The composition of coating layers deposited on the surface of 12Kh18N10T stainless steel (similar to 321 AISI) in the TaBr〈sub〉5〈/sub〉-Cd-He system at temperatures ranging from 623 К to 1423 К and at a pressure of 1 atm was evaluated using thermodynamic analysis. Tantalum-based coatings were deposited on 12Kh18N10T and tungsten substrates by chemical vapour deposition (CVD) using reduction of tantalum bromide vapour by cadmium vapour at а temperature of 1023 К. The formation of β-Ta, diffuse layers of Ta-Fe as well as Fe〈sub〉2〈/sub〉Ta-based Laves phase in the deposited coating layers has been analysed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): A. Kilicaslan, O. Zabeida, E. Bousser, T. Schmitt, J.E. Klemberg-Sapieha, L. Martinu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present work, we reviewed and studied the fabrication process of hard erosion resistant TiN protective coatings on the inner surfaces of narrow tubes using a Non-Line-Of-Sight (NLOS) approach. Initially, while evaluating the growth of DLC and TiN by the CW RF PECVD process, we found that the use of a hydrocarbon precursor to obtain DLC provides uniform film thickness along the tube axis, while the use of the TiCl〈sub〉4〈/sub〉 precursor for TiN leads to a significant thickness nonuniformity of 80% and large differences between the film properties in the middle of the tube compared to the edges. Following detailed plasma analysis, we demonstrate that the uniformity can be substantially enhanced by applying pulsed-DC PECVD, while uniform (better than 20%) hard TiN films were prepared by low-frequency (5 kHz) pulsed-DC PECVD. The TiN films (about 12 μm thick), systematically studied by SEM, XRD, and nanoindentation, when prepared under optimized conditions, exhibit high hardness and reduced Young's modulus (25 and 225 GPa, respectively) corresponding to the (111) preferred crystallographic orientation, and a very low Cl contamination (〈3%). The film uniformity has been correlated to that of the discharge light emission intensity along the tube axis, and the microstructural evolution is interpreted in terms of surface densification due to substrate temperature and ion bombardment of the inner surface. The pulsed DC PECVD NLOS process providing TiN coatings with a hardness markedly higher than the hardness of the erodent particles and with a solid particle erosion resistance increased by a factor of 〉15 compared to the bare substrate is well suited for the protection of aerospace, manufacturing, and other critical components with a complex shape of inner surfaces.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): J. Drieu La Rochelle, P. Godard, C. Mocuta, D. Thiaudière, J. Nicolai, M.F. Beaufort, M. Drouet, P.O. Renault〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, in situ measurements of synchrotron x-ray pole figure have been performed during incremental uniaxial deformation test on a single-crystal gold foil. The 50 nm thick Au thin film was elaborated by ion sputtering at 400 °C on NaCl single crystal as a template. The resulting film consists of a single-crystal gold foil containing a small density of thin and small {111} growth twins (few nm thick and few tens of nm long) revealed by x-ray pole figure measurement. The as-deposited gold single crystal was then transferred onto flexible polyimide substrates for deformation test. This work focuses on the relative evolution of the diffracting volume related to growth twins during a loading-unloading tensile test. Macroscopic applied deformations and x-ray pole figures were measured in situ during a uniaxial tensile test in the Au [110] direction. X-ray pole figures clearly evidenced the relative evolution of the diffracting volumes related to the (111) and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mfenced open="(" close=")"〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈mn〉1〈/mn〉〈/mrow〉〈/mfenced〉〈/math〉 twins which exhibit a huge increase of about 450% at a uniaxial applied true strain of about 4%. The concomitant variation of diffracting volumes related to the two other twin variants (namely 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si2.svg"〉〈mfenced open="(" close=")"〉〈mrow〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈mn〉11〈/mn〉〈/mrow〉〈/mfenced〉〈/math〉 and 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si5.svg"〉〈mfenced open="(" close=")"〉〈mrow〉〈mn〉1〈/mn〉〈mover accent="true"〉〈mn〉1〈/mn〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈mn〉1〈/mn〉〈/mrow〉〈/mfenced〉〈/math〉 twins) shows a relatively low decrease of 25%. The results open out onto a true strain-twinning volume hysteresis curve, indicative of the deformation mechanisms of gold thin films that can be interpreted as a twinning-detwinning mechanism.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Yanmeng Cheng, Pengfei Liu, Peng Xiao, Zhuan Li, Tianhui Jiang, Yanqi Huang, Yang Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Carbon fibers reinforced epoxy (CF/epoxy) composites have been used in orthopedic and dental implants. However, the inert surface of CF/epoxy composites cannot show ability of forming direct bone bonding with autologous bone during implantation. In order to improve the bioactivity of CF/epoxy composites, the different chemical modifications (concentrated sulfuric acid (97 wt%), CaCl〈sub〉2〈/sub〉 solution, concentrated sulfuric acid (97 wt%) + CaCl〈sub〉2〈/sub〉 solution) were used to modify its original surface. The bioactivity of modified CF/epoxy composites was evaluated by in vitro apatite formation ability in simulated body fluids (SBF). The result showed that -SO〈sub〉3〈/sub〉H and Ca〈sup〉2+〈/sup〉 were introduced on the of sample surface after chemical modification. Samples modified with concentrated sulfuric acid (97 wt%) and CaCl〈sub〉2〈/sub〉 solution showed the best bioactivity. In addition, a uniform and dense apatite coating was formed on the surface of functionalized CF/epoxy composites after soaking in SBF and the presence of -SO〈sub〉3〈/sub〉H would significantly improve the bond between the coating and the substrate. The transformation process of apatite morphology during its formation and the mechanism of apatite formation on the functionalized CF/epoxy composites were also analyzed systematically.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): N. López Perrusquia, M.A. Doñu Ruiz, C.R. Torres San Miguel, G.J. Pérez Mendoza, J.V. Cortes Suarez, A. Juanico Loran〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉In this study present the benefit of boride coating on surface of ASTM A-36 steel and the evaluation of the properties of the hard coatings under hydrogen permeation. The ASTM A-36 steel was surface hardened by diffusion boron atoms at temperature at 950 °C for 3, 5, and 7 h using the dehydrated boron paste-pack method. The hard coatings obtained on surface A-36 steel were examined using scanning electron microscopy combined with energy dispersive spectrometry and X-ray diffraction. In addition, the hydrogen was introduce into samples with hard coating through cathodic charging applying a current density of 50 mA/cm〈sup〉2〈/sup〉 by 0.5 M sulfuric acid solution kept at a room temperature. Three-point bending and instrument nanoindentation were evaluated on sample borided before and after hydrogen charged.〈/p〉 〈p〉Microstructural characterization revealed bilayer (FeB + Fe〈sub〉2〈/sub〉B) coatings with saw-tooth morphology and the thicknes values of FeB and Fe〈sub〉2〈/sub〉B were in range of 25.30 to 45.3 μm and 77.09 to 187.10 μm, respectively. After hydrogen charged, the microstructure delayed the diffusion of hydrogen, reducing the formation of cracks by increasing the FeB and Fe〈sub〉2〈/sub〉B coatings. However. the hardness of the samples tends to increase while the elastic modulus decrease. As well as the static load by bending test decrease due to steel ASTM A-36‑hydrogen interaction.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Sayantan Ray, Suman Saha, Sk. Hasanur Rahaman, Arnab Bhattacharjee, Nina Daneu, Zoran Samardžija, Jui Chakraborty〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present communication reports the variation in surface characteristics of bilayered coating of phosphate free bioactive glass (PFBG) on SS316L substrate at simulated conditions, w.r.t both pH and temperature, to understand the suitability of the same for load bearing applications. The coated substrates were subjected to both physiological (7.4) and pathophysiological (4.5) pH conditions, considering two working temperatures of 37 °C and 45 °C, related to the real time scenario, in the post implantation period. Herewith, a faster dissolution of the PFBG network could be obtained at higher temperature (45 °C) and acidic pH (4.5) conditions, leading to a degraded surface texture, while the same at 37 °C and pH 7.4, exhibited an almost intact surface. The observation was corroborated using atomic force microscopy which exhibited an exponential increase in the nanoscale surface roughness of the coating at lower pH and at higher temperature conditions. The ionic Ca〈sup〉2+〈/sup〉 dissolution kinetics of the PFBG coating followed by their cellular interaction were assessed using MC3T3 cell line, which showed a distinct difference compared to the as prepared PFBG coated substrate. Further, we made an attempt to assess the role of the calcium binding protein, calmodulin and its major target, calcium-calmodulin kinase II alpha (CAMKIIα) in osteoblast (MC3T3) differentiation, cultured on the PFBG coated SS316L substrates, subject to the experimental parameters as abovementioned. The results indicated significance of the real time conditions at the site of application of a bioactive glass coating on load bearing SS316L based implant material.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Henning Moldenhauer, Alexandra Wittig, David Kokalj, Dominic Stangier, Andreas Brümmer, Wolfgang Tillmann, Jörg Debus〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Raman spectroscopy is used to investigate the structural and tribological properties of HiPIMS sputtered MoS〈sub〉〈em〉x〈/em〉〈/sub〉 thin films which were post-growth-annealed at different temperatures. The Raman scattering combined with X-ray diffraction determines a reduction in the residual strain within the MoS〈sub〉〈em〉x〈/em〉〈/sub〉 layers with increasing annealing temperature. In the high-temperature annealed coatings a Raman signature at 40 cm〈sup〉−1〈/sup〉 emerges, which results from a strengthening of the inter-layer van-der-Waals interaction. This observation indicates that the thermally annealed MoS〈sub〉〈em〉x〈/em〉〈/sub〉 thin films become more resistant against shear forces, which is manifested in an increase of the coefficient of friction measured with a ball-on-disc tribometer. The coefficient of friction moreover decreases with lowering the sulfur/molybdenum ratio which, in turn, depends on the substrate and annealing temperatures. Furthermore, a Raman forbidden mode may be exploited to detect stacking faults within the sputtered coatings. Its observation is realized through resonant excitation of an MoS〈sub〉2〈/sub〉 exciton at about 633 nm.〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Lu Tian, Weiping Li, Hui Ye, Liqun Zhu, Haining Chen, Huicong Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Superhydrophilic and underwater superoleophobic materials for oil/water separation have recently attracted much attention due to the urgent needs of water protection. However, the environmental problems, complex preparation process and poor stabilities seriously restricted the practical applications. Herein, a waterborne organic–inorganic composite coating was prepared by mechanical mixing a silicone acrylic emulsion with nano-silica particles. The silica particles could be introduced to polymeric latexes to generate the cross-linked structure due to the polycondensation between hydroxyl groups. A simple spray technique was applied to deposit the as-prepared composite coating on a stainless steel mesh which exhibited a favourable superhydrophilicity (nearly 0°) and underwater superoleophobicity (above 155°) towards various oil droplets. The coated mesh presented a high separation efficiency of above 99% towards a series of light oil–water mixtures and it also showed a good recyclability after 30 separation cycles. Furthermore, the coated mesh kept excellent underwater superoleophobicity under a series of pH solutions and immersion tests in water and 3.5 wt% NaCl solution. Therefore, the as-prepared mesh is highlighted in its simple and environmental fabrication, high separation efficiency, good recyclability, excellent chemical stability and water resistance, exhibiting a bright prospect for scalable production.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219308643-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Faiz Muhaffel, Mertcan Kaba, Grzegorz Cempura, Bora Derin, Adam Kruk, Erdem Atar, Huseyin Cimenoglu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present work, the influence of alumina (Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) and zirconia (ZrO〈sub〉2〈/sub〉) incorporation on the structural properties and wear resistance of titania (TiO〈sub〉2〈/sub〉) based micro-arc oxidation (MAO) coatings fabricated on Ti6Al4V alloy was studied. For this purpose MAO was employed in a silicate-based electrolyte with and without additions of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and ZrO〈sub〉2〈/sub〉 particles. The structural properties were determined via X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy analysis and an energy dispersive spectrometer (EDS) equipped scanning electron microscope (SEM). Furthermore, thermochemical simulations were made by using FactSage 7.3. Mechanical properties of the MAO coatings were determined by hardness measurements and dry sliding reciprocating wear tests. Structural examinations revealed that the MAO coatings fabricated in Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and ZrO〈sub〉2〈/sub〉 added electrolytes comprised of these oxides and their complex forms (Al〈sub〉2〈/sub〉TiO〈sub〉5〈/sub〉 and ZrTiO〈sub〉4〈/sub〉, respectively) along with TiO〈sub〉2〈/sub〉 and amorphous silica (SiO〈sub〉2〈/sub〉). Although incorporations of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and ZrO〈sub〉2〈/sub〉 did not remarkably improve the hardness of the MAO coatings, the highest wear resistance was obtained from the one formed in the ZrO〈sub〉2〈/sub〉 added electrolyte. On the other hand, the MAO coating fabricated in the Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 added electrolyte exhibited lower wear resistance than that of fabricated in the particle-free silicate-based electrolyte.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Balachander Gnanasekaran, Gui-Rong Liu, Yao Fu, Guangyu Wang, Weilong Niu, Tao Lin〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cold spray process has been of great interest in coating and additive manufacturing because it does not need heat supply during impact. Cold spray generally uses particles of diameters 10 μm to 50 μm traveling at velocities of 300 m/s to 1200 m/s, and it takes place at very small time and length scales. Thus, it becomes difficult to observe the detailed process experimentally. The primary objective of this study is to use SPH and highlight its capability for modeling cold-spray process. A novel way of establishing boundary conditions using Monaghan type 2 particles is adopted in this study. Additionally,our SPH model includes failure modeling for copper particle impacts. Particles of different sizes and at different angles are studied to reveal the effects of impact which includes recording effective plastic strain, deformation and temperature. It was found that larger particles had greater ability to adhere to the surface of the substrate and an impact angle between 80° and 90° has higher chances of adherence to the substrate. An increase in maximum effective plastic strain is seen which causes thermal softening leading to plastic flow of material. This fluid-like flow causes adherence of the particle on the substrate. Finally, the in-house SPH procedure is extended to simulate three-dimensional cold spray problems with multiple particles.〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Junrong Tang, Zhipo Zhao, Ning Li, Xiang Qiu, Yanfang Shen, Xinyu Cui, Hao Du, Jiqiang Wang, Tianying Xiong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, three types of Ta feedstock powders [i.e., hydrogenation de-hydrogenation (HDH)-1, HDH-2 and mechanical pulverization (MP)] were deposited on Ti6Al4V substrate by cold spray and the influence of feedstock powder on microstructure and mechanical properties of the deposited coating was firstly studied. All depositions showed no significant oxidation, but grain refinement. Cold sprayed coatings revealed two distinct microstructures, a large number of ultrafine grains at highly deformed splat boundaries and original grains in the middle of the particles. Powder morphology influenced deposition quality more than propellant gas temperature. Results showed that the deposition prepared by porous HDH-1-Ta powders performed the best quality with the relatively flat section, the lowest porosity (0.93–1.77%), the highest deposition efficiency, the highest microhardness (345–441 HV〈sub〉0.1〈/sub〉) and the decent adhesion bonding strength (39–41 MPa). This was mainly because HDH-1-Ta powders possess porous morphology and exhibit excellent compressibility and compaction behavior during deposition. Thus, porous HDH-1 powders may hold promise as a cost effective alternative for Ta cold spray depositions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Li Zhang, Yi Chen, Mo-xian Chen, Long Huang, Hou-ping Wu, Tao Liu, Xiang-jun Xiong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To achieve a better understanding of the interaction between the film and the ductile Co-based binder phase in cemented carbide substrate and the associated interface microstructure evolution, a model alloy of 85.1Co–9.2W–4.7Cr〈sub〉3〈/sub〉C〈sub〉2〈/sub〉–1.0VC was prepared. Ti〈sub〉0.94〈/sub〉Si〈sub〉0.06〈/sub〉N/TiAlSiN/Al〈sub〉0.52〈/sub〉Ti〈sub〉0.48〈/sub〉N coating was deposited on the Co-based alloy by a DC magnetron sputtering technique. High-resolution transmission electron microscopy observation and high-resolution energy dispersion spectrum analysis reveal a complex film-substrate structure. An interface-centered bilateral transition layer, i.e., nanocrystalline AlTiN and hcp-Co, and double sub-transition layers, i.e., bcc-W and disordered arrangement of Co atoms are identified. The formation mechanisms for the sub-transition and transition layer are discussed. Based on the AlTiN transition layer phenomenon, the reason for the substantial texture coefficient 〈em〉TC〈/em〉〈sub〉(111)〈/sub〉 difference between fcc-AlTiN and fcc-TiSiN (5.9/3.6 vs. 2.9) is discussed. Considering the significance of the observed semi-coherent relationship for the bcc-W/AlTiN interface and the positive adaptability of cobalt, suggestions are proposed for the composition design of cemented carbide substrate and the film deposition rate controlling.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219308771-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Bo Huang, Chao Zhang, Ga Zhang, Hanlin Liao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermal sprayed Fe-based amorphous coatings exhibit excellent wear and corrosion resistance, and thus have been widely utilized for enhancing the performance of material surfaces. In this paper, important research progresses achieved in regards to deposition technologies and properties of thermal sprayed Fe-based amorphous coatings are reviewed. In particular, the dependence of wear and corrosion resistance of the coatings on processing parameters, e.g., kinetic energy, particle size, gas flow rate, and heat treatment temperature are summarized. Moreover, the utilization of reinforced phases and alloy elements for enhancing the wear and corrosion resistance of the coatings are presented. It is expected that future endeavors will be dedicated to the formation mechanism of amorphous phase and “processing parameter-microstructure-macroscopic property” relationship of Fe-based amorphous coatings.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Tomoya Higuchi, Masao Noma, Michiru Yamashita, Keiichiro Urabe, Shigehiko Hasegawa, Koji Eriguchi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The surface modification of a boron nitride (BN) film by plasma exposure was investigated by means of nanoindentation analyses and molecular dynamics simulations. A μm-thick BN film composed of nanoscale 〈em〉sp〈/em〉〈sup〉3〈/sup〉-bonded phases in the turbostratic (〈em〉sp〈/em〉〈sup〉2〈/sup〉-bonded) BN domain was prepared on a Si substrate using a reactive plasma-assisted coating system. Then, the BN films were exposed to an inductively coupled Ar plasma under various bias power conditions. The change of the morphology and mechanical properties in the surface region due to the plasma exposure was evaluated with respect to the dependence on the energy of incident Ar ions (〈em〉E〈/em〉〈sub〉ion〈/sub〉). A nanoindentation test under various contact depths identified the formation of a surface plasma-damaged layer (a few nm thick) where the nanoindentation hardness (〈em〉H〈/em〉〈sub〉IT〈/sub〉) was changed in response to the Ar ion irradiation. A molecular dynamics (MD) simulation predicted also the 〈em〉E〈/em〉〈sub〉ion〈/sub〉-dependence of the reconstruction of the 〈em〉sp〈/em〉〈sup〉3〈/sup〉〈em〉-〈/em〉bonded phases in a few nm-thick layer on the surface. The presence of a damaged-layer plays an important role in the mechanical properties of the BN/Si structures.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Santigopal Samanta, Arup Kumar Halder, Yashwardhan Deo, Sounak Guha, Monojit Dutta〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of 〈em〉Mn〈/em〉 and 〈em〉Cr〈/em〉 on the surface selective oxidation, segregation and hot-dip galvanizing was studied in three 〈em〉Fe〈/em〉-〈em〉Mn〈/em〉 alloys with ∼0.2 wt% 〈em〉Al〈/em〉 and two 〈em〉Fe〈/em〉 − 〈em〉Mn〈/em〉 alloys with ∼0.5 wt% 〈em〉Cr〈/em〉 in an HDPS (Hot-dip Process Simulator) following industrial CGL (Continuous Galvanizing Line) conditions. The 〈em〉Mn〈/em〉 content was varied from 1.5 to 3.6 wt% in the alloys. The alloys were subjected to the same thermal cycle following continuous annealing (CA) at 800 °C in 〈em〉N〈/em〉〈sub〉2〈/sub〉 − 5〈em〉%H〈/em〉〈sub〉2〈/sub〉 gas atmosphere with −40 °C dew point and then hot-dipping in 〈em〉Zn〈/em〉 - 0.20 wt% 〈em〉Al〈/em〉 bath at 460 °C. The oxidation tendency of 〈em〉Mn〈/em〉, 〈em〉Al〈/em〉 and 〈em〉Cr〈/em〉 during annealing was calculated using FactSage software. GDOES (Glow Discharge Optical Emission Spectroscopy) measurements showed a higher extent and depth of segregation for 〈em〉Mn〈/em〉 with increasing bulk concentration during the CA. It was observed that 〈em〉Cr〈/em〉 segregates comparatively less near the annealed surface in the presence of more 〈em〉Mn〈/em〉. XPS (X-ray Photoelectron Spectroscopy) measurements revealed the formation of simple 〈em〉MnO〈/em〉 in 〈em〉Fe〈/em〉-〈em〉Mn〈/em〉-〈em〉Al〈/em〉 alloys and complex 〈em〉MnCr〈/em〉〈sub〉2〈/sub〉〈em〉O〈/em〉〈sub〉4〈/sub〉 in 〈em〉Fe〈/em〉-〈em〉Mn〈/em〉-〈em〉Cr〈/em〉 alloys. Contrary to the thermodynamic calculations, no 〈em〉Al〈/em〉-oxides were detected at the annealed surfaces of 〈em〉Fe〈/em〉-〈em〉Mn〈/em〉-〈em〉Al〈/em〉 alloys during the XPS study. The hot-dip 〈em〉Zn〈/em〉 coatability was determined by measuring the number density of uncoated spots using 3D CLSM (Confocal Laser Scanning Microscopy) and by visual inspection. The 〈em〉Fe〈/em〉-〈em〉Mn〈/em〉-〈em〉Cr〈/em〉 alloys displayed a better hot-dip 〈em〉Zn〈/em〉-coating compared to 〈em〉Fe〈/em〉-〈em〉Mn〈/em〉-〈em〉Al〈/em〉 alloys. The conclusions of the present study are also critically discussed considering the literature findings.〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): A. Manochehrian, A. Heidarpour, Y. Mazaheri, S. Ghasemi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study described surface reinforcing of A356 aluminum alloy with 2.5, 5, and 7.5 vol% nanolayered Ti〈sub〉3〈/sub〉AlC〈sub〉2〈/sub〉 MAX phase particles. The friction stir processing (FSP) was used to fabricate these surface composites. The surface composites were characterized by different routes such as optical and electron microscopy, microhardness, tensile, and wear tests. The OM and SEM micrographs showed that the application of FSP resulted in microstructural refinement and modification because of reducing porosity, diminishing coarse dendrites of primary aluminum, fragmenting of coarse silicon needle-shaped particles, uniform distributing of fine silicon particle in the substrate. This microstructural evolution led to increasing in microhardness and tensile values. The microhardness and tensile strength values of the as-received alloy and A356-7.5 vol% Ti〈sub〉3〈/sub〉AlC〈sub〉2〈/sub〉 surface composite were about 68 HV and 112 MPa, and 87 HV and 184 MPa, respectively. Surface nanocomposites showed significantly lower friction coefficient values and lower wear rates than the substrate. Scanning electron microscopy micrographs revealed that the abrasive wear with different extent and characteristics was the dominant wear mechanism.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): A. Lanzutti, A. Raffaelli, M. Magnan, L. Fedrizzi, M. Regis, E. Marin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Ti alloys suffer from intensive wear. To improve these properties, a surface treatment is required (coatings, surface thermal treatment, etc.). One of the major concerns regarding these treatments is that the treatment temperature needs to be controlled in order to avoid microstructural modifications.〈/p〉 〈p〉In this work, an attempt to modify a thin alloy surface layer alone has been performed by means of induction nitriding. By saturating the heating chamber with N, it is possible to produce controlled thickness nitride layers. Current (650–750 A) and cycle number (2–4 with a duration of 8 s each) were varied, and the top view and cross sections of the produced samples were characterized by means of stylus profilometery, SEM (Scanning Electron Microscopy) and visible light microscopy. The produced samples were then studied by microhardness and tensile testing to determine their mechanical properties. Fretting tests were also performed in order to evaluate the wearing behaviour of the surface layers in a corrosive media.〈/p〉 〈p〉The results showed that Ti alloys can be induction nitrided. The process parameters have a strong influence on the formation of TiN and alpha case layers. These layers can affect the mechanical properties and fretting resistance of the samples.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219308679-ga1.jpg" width="344" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): M. Nazari, H. Eskandari, F. Khodabakhshi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, by the implementation of multi-pass friction stir processing (FSP) an advanced AA6061-Graphene-TiB〈sub〉2〈/sub〉 hybrid surface nanocomposite is produced in contrast to the AA6061-Graphene and AA6061-TiB〈sub〉2〈/sub〉 single composites. Effects of micro-sized TiB〈sub〉2〈/sub〉 (10-30 wt%) and nano-sized graphene (0.5-2 wt%) particles on the microstructure and mechanical property of aluminum alloy are investigated. Moderate chemical composition as ~20 wt% TiB〈sub〉2〈/sub〉 and 1 wt% graphene for the hybrid nanocomposite system yielded the best combinations of mechanical property overcome the wear-strength trade-off. Such optimum incorporation of hybrid inclusions mixture led a hardness increasing up to about two times higher, a yield strength improvement up to ~225 MPa (~300% increasing ratio), and an elongation loss down to ~9%. A considerable reduction in the coefficient of friction ~23% is revealed with the dominant contribution of sliding wear fractographic features on the worn-out fracture surface due to the presence of graphene in the nanocomposite structure acting as the lubricant agent.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): D. Fernández-Valdés, A. Meneses-Amador, G.A. Rodríguez-Castro, I. Arzate-Vázquez, I. Campos-Silva, J.L. Nava-Sánchez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, an experimental-numerical evaluation of the standing contact fatigue testing of a nitrided AISI 316L steel was developed. The nitride layers were formed at the surface of an AISI 316L steel by a salt bath nitriding process at a temperature of 580 °C for 1, 3 and 5 h of exposure time, obtaining three different layer thicknesses. In order to know the mechanical response and the different mechanisms of damage associated with the standing contact fatigue test, Hertzian tests were performed on a MTS machine by cyclic loading of a sphere on a flat surface formed by the layer/substrate system. The standing contact fatigue test was developed through two main stages. First, the critical loads for each treatment condition were determined by monotonic tests, where the appearance of circular cracks was considered as the failure criterion. Subsequently, cyclic subcritical loads were applied at a frequency of 5 Hz. A numerical model based on the finite element method was developed to evaluate the stress field generated in the system by cyclic contact loads. The results indicate that the thinnest thickness of nitride layer exhibits better resistance to standing contact fatigue.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Anja Buchwalder, Rolf Zenker〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉With their specific layer features and properties, surface treatments such as thermochemical treatment (nitriding, boriding) and hard coating cover a broad field of application in the wear and corrosion protection of steels. Limitations exist, however, when applying these surface treatments to softer materials, such as cast irons and aluminum alloys in terms of both their treatability and load-bearing capacity.〈/p〉 〈p〉This contribution deals with investigations into duplex surface treatments, where a pre- and post-electron beam (EB) surface treatment (e.g., hardening, remelting, alloying etc.) was combined with one of the above-mentioned treatments. Among other characteristics, the thermal EB surface treatments were characterized by high heating and cooling rates that facilitated the generation of a variety of non-equilibrium microstructures, which exhibited increased hardness and had minimal thermal effects on the surrounding base material. Furthermore, the layer thicknesses were one or two orders of magnitude higher than those generated by thermochemical treatment or hard coating.〈/p〉 〈p〉Based on the comprehensive results and using cast irons and Al alloys as examples, the study demonstrates the extent to which duplex treatments can overcome the aforementioned limitations, and how the tribological and/or corrosive load behavior is affected. The property profiles achieved after duplex surface treatment were strongly dependent on the inherent microstructural and chemical processes. These complex processes were influenced by a range of factors, such as the thermal stability of the EB surface layer generated in the first process step, the respective temperature and time period of the secondary process, etc.〈/p〉 〈p〉Hardness measurements, scratch tests, unlubricated pin-on-disc wear tests using different normal loads and potentiodynamic corrosion tests were realized to facilitate characterization of the different load behaviors of the single- and duplex-treated layers.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Miqi Wang, Zehua Zhou, Yu Yi, Zehua Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Residual strength method was first highlighted as a quantitative analysis method to evaluate thermal shock resistance (TSR) of coating. TSR of plasma sprayed Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-13 wt%TiO〈sub〉2〈/sub〉 coating on metal substrate was investigated by residual strength method and conventional cyclic quenching method, respectively. The results revealed that residual strength method was superior to cyclic quenching method because critical thermal-shock (TS) temperature of the coating was directly pointed out, which meant that it could be deemed as a novel method for quantitative evaluation for TSR of the coating. Critical TS temperature of the tested coating was 800 °C derived from the strength-temperature curve according to residual strength method. For cyclic quenching method, 850 °C was an un-safe temperature but 800 °C was an equivocal one in TSR evaluation of the coating. After 400 °C TS, fracture occurred at the interface between the ceramic layer and the adhesive layer, and the main mechanism was intergranular fracture. But fracture was both observed in the ceramic layer and the adhesive layer after 850 °C TS, and the mechanism transformed into quasi-cleavage of both transgranular and intergranular fracture.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Sisi Luo, Qun Wang, Renfeng Ye, Chidambaram Seshadri Ramachandran〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this investigation, the effect of electrolyte concentration parameters on the plasma electrolytic oxidation (PEO) coatings on Ti-6Al-4V alloy were investigated by an orthogonal experiment involving four factors with three levels by changing the concentration of Ca(CH〈sub〉3〈/sub〉COO)〈sub〉2〈/sub〉·H〈sub〉2〈/sub〉O, NaH〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O, Ethylene-diamine-tetra-acetic acid (EDTA) and NaOH, respectively. The self-corrosion current density, Ca/P, bond strength, phase composition and microstructure of the coatings were studied in detail. The results indicate that the nine PEO coatings had unevenly distributed porous structures comprising different ratios of titanium, rutile, and anatase phase. The effect of electrolyte concentration parameters on the properties and performance of coatings are sequenced hierarchically as follows: EDTA 〉 NaOH 〉 Ca(CH〈sub〉3〈/sub〉COO)〈sub〉2〈/sub〉·H〈sub〉2〈/sub〉O 〉 NaH〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O for corrosion resistance, NaOH 〉 EDTA 〉 Ca(CH〈sub〉3〈/sub〉COO)2·H〈sub〉2〈/sub〉O 〉 NaH〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O for Ca/P, Ca(CH〈sub〉3〈/sub〉COO)〈sub〉2〈/sub〉·H〈sub〉2〈/sub〉O 〉 NaH〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉·2H〈sub〉2〈/sub〉O 〉 NaOH 〉 EDTA for bond strength. The highest bond strength of the PEO coatings can reach as high as 60 MPa. The optimized electrolyte composition for the Ti-6Al-4V is: C〈sub〉Ca(g/L)〈/sub〉 = 11.44 g/L, C〈sub〉P(g/L)〈/sub〉 = 5.72 g/L, C〈sub〉EDTA(g/L)〈/sub〉 = 10 g/L, C〈sub〉NaOH(g/L)〈/sub〉 = 15 g/L and the corresponding PEO coating had adequate thickness (11.78 μm), satisfactory bond strength (33.69 MPa) and a fitting Ca/P ratio of 1.68.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Jing Liu, Yu Chen, Jian Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, Ni–Mo–Si alloy coatings with different compositions were prepared on the surface of AISI 1045 steel by laser cladding. The microstructure and phase composition of different alloy coatings were studied by SEM, EDS and XRD. The oxidation resistance of the alloy coating was investigated in the static air environment at 800 °C. The results showed that: All the γ-Ni〈sub〉ss〈/sub〉/Mo〈sub〉2〈/sub〉Ni〈sub〉3〈/sub〉Si alloy coatings exhibited similar oxidation behavior and the oxidation kinetics curves followed a comprehensive linear-parabolic law. The total mass gain of N60, N55 and N50 alloy coating were 3.28 mg/cm〈sup〉2〈/sup〉, 2.98 mg/cm〈sup〉2〈/sup〉, 2.69 mg/cm〈sup〉2〈/sup〉, respectively. The oxide layers covered on the alloys were uniform and dense, which were mainly composed of NiO, Fe〈sub〉2〈/sub〉SiO〈sub〉4〈/sub〉, SiO〈sub〉2〈/sub〉 and MoO〈sub〉3〈/sub〉. With the increasing Si content in the designed alloy, a continuous SiO〈sub〉2〈/sub〉 film formed inside the oxide layer, which could effectively hinder the diffusion of oxygen and Ni〈sup〉2+〈/sup〉 in the oxide layer. Among the designed alloy coatings, N50 coating exhibited the lowest oxidation rate and the best oxidation resistance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Yen-Yu Chen, Sheng-Bo Hung, Chaur-Jeng Wang, Wen-Chung Wei, Jyh-Wei Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High entropy alloys (HEA) show outstanding thermodynamic, mechanical or thermal properties as compared with pure metals or binary alloys. Among several kinds of HEAs, the refractory element containing HEAs exhibit relatively high thermal stability and better mechanical properties at elevated temperature. In this study, the V〈sub〉19.2〈/sub〉Nb〈sub〉19.4〈/sub〉Mo〈sub〉20.3〈/sub〉Ta〈sub〉19.5〈/sub〉W〈sub〉21.6〈/sub〉 high entropy alloy thin films were deposited on the AISI 304 stainless steel substrates by a magnetron sputtering process. The oxidation behavior and electrical conductivities of HEA thin films at different temperatures were evaluated. The body-centered cubic (BCC) structure of HEA thin film can be kept up to 500 °C oxidation, and it transferred to V-Nb-Mo-Ta-W based oxides and then turned to iron contained oxide phases when the oxidation temperature increased to 700 °C. The electrical resistivity of thin film increased with oxidation temperature. The electrochemical impedance spectroscope (EIS) analysis showed that the total apparent resistivity values of 304SS substrate coated with V〈sub〉19.2〈/sub〉Nb〈sub〉19.4〈/sub〉Mo〈sub〉20.3〈/sub〉Ta〈sub〉19.5〈/sub〉W〈sub〉21.6〈/sub〉 high entropy alloy thin film at 600, 700 and 800 °C were 5.80, 6.91, and 7.71 Ω·cm, respectively. The electrical resistance of the HEA coated sample was contributed by the oxide resistance and interface polarization. Through the electrical property analysis at high temperatures, the HEA thin film can provide a protection layer to the 304SS substrate and kept the sample's high temperature apparent resistivity to a relatively lower value.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Wolfgang Tillmann, Nelson Filipe Lopes Dias, Dominic Stangier, Wolfgang Maus-Friedrichs, René Gustus, Carl Arne Thomann, Henning Moldenhauer, Jörg Debus〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Ensuring a high adhesion of amorphous carbon films to steel substrates remains a challenging task, sustaining continuous research efforts to improve the adhesion strength. Besides the interlayer system and the substrate material, surface pretreatments have a significant impact on the adhesion behavior. Within this context, the influence of the High Power Impulse Magnetron Sputtering (HiPIMS) pretreatment on the adhesion of magnetron sputtered hydrogenfree (a-C) and hydrogenated (a-C:H) amorphous carbon films with a chromium carbide (CrC) interlayer on 16MnCr5 steel is investigated. The plasma treatment consisted of 30 min Ar ion etching as well as a sequential 5 min of HiPIMS-pretreatment with a Cr cathode. Subsequently this pretreatment was compared to a procedure without utilizing the HiPIMS technique. The impact of the HiPIMS-pretreatment on the structure of the film was systematically analyzed by taking the CrC interlayer as well as the entire film structure into consideration.〈/p〉 〈p〉The adhesion strength of the a-C and a-C:H films is significantly improved by the formation of a Cr HiPIMS-nanolayer in the substrate/film interface. In scratch tests, the critical load 〈em〉L〈/em〉〈sub〉c3〈/sub〉 for a total film delamination increases from 43 ± 4 to 59 ± 3 N and from 48 ± 2 to 64 ± 3 N for the a-C and a-C:H film. The improved adhesion behavior of the carbon films is ascribed to the increased adhesion of the CrC interlayer, which did not delaminate when scratched with a load up to 159 ± 18 N. Complementary Rockwell indentation tests reveal that the HiPIMS-pretreatment improves the adhesion class from HF6 to HF4 and from HF5 to HF3 for a-C and a-C:H. The enhanced adhesion is essential to exploit the properties of a-C and a-C:H films in applications with high loads. In conclusion, the HiPIMS-pretreatment has proven to be a promising technique to increase the adhesion strength of carbon films.〈/p〉 〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219308278-ga1.jpg" width="447" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Jian Dong, Yanhui Sun, Feiyu He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, the aluminide coating was prepared by a combined process. The coating thickness and phase structure at different aluminizing temperatures and times were investigated. In addition, the thermodynamics and kinetics of the pack cementation aluminizing process were studied. The aluminizing temperature had influence on the coating phase structure. As the temperature and time increased, the coating thickened. In the process of pack cementation aluminizing, the Fe〈sub〉2〈/sub〉Al〈sub〉5〈/sub〉 phase was formed first, followed by the FeAl and FeAl〈sub〉3〈/sub〉 phases. As the temperature was lowered to below 422 °C, the Fe〈sub〉3〈/sub〉Al phase began to form. The kinetic study showed that the low-temperature aluminizing process had a low activation energy value of 164.78 kJ/mol. This research provided a theoretical basis for the parameter selection of low-temperature pack cementation aluminizing process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Lu Zhu, Yousen Zhu, Xuanru Ren, Ping Zhang, Jianghao Qiao, Peizhong Feng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉MoSi〈sub〉2〈/sub〉-MoB-ZrO〈sub〉2〈/sub〉 composite powders are one-step synthesized prepared by self-propagating high-temperature synthesis (SHS), which are further utilized to prepare the oxidation protective coatings by spark plasma sintering (SPS) method on molybdenum substrate. Microstructure and properties of the coatings were investigated and determined. Oxidation behavior of the coatings at high temperature was also studied. The results showed that the composite coating is dense and crack-free due to the addition of ZrO〈sub〉2〈/sub〉, which is beneficial for the decrease of mismatch in coefficient of thermal expansion, and no void exists in the diffusion layer owing to the diffusion of Si, which is inhibited by adding MoB. Compared with the pure MoSi2 coating, the high hardness of the composite coating is enhanced by about 20% while the fracture toughness of the composite coating is improved by about 25%, which makes the occurrence of intergranular fracture, crack deflection and crack bridging. After oxidation at 1400 °C for 80 h, MoSi〈sub〉2〈/sub〉 coating failed while xMoSi〈sub〉2〈/sub〉-MoB-3ZrO〈sub〉2〈/sub〉 (x = 3, 4, 5) composite coating still kept its protective effect. Only a little substrate is consumed during oxidation and improved oxidation resistance is gained by MoSi〈sub〉2〈/sub〉-MoB-ZrO〈sub〉2〈/sub〉 composite coating. 3MoSi〈sub〉2〈/sub〉-MoB-3ZrO〈sub〉2〈/sub〉 coating shows the relatively best oxidation resistance due to the formation of crack-free oxide film on the surface of the coating.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): František Lofaj, Margita Kabátová, Lenka Kvetková, Jozef Dobrovodský, Vladimír Girman〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The plasma polymerization processes during hybrid PVD-PECVD deposition, structure, hydrogenation, hybridization, hardness and coefficients of friction in W-C:H coatings prepared by direct current magnetron sputtering (DCMS), High Power Impulse Magnetron Sputtering (HiPIMS) and High Target Utilization Sputtering (HiTUS) were reviewed as a function of acetylene (0–12 sccm C〈sub〉2〈/sub〉H〈sub〉2〈/sub〉) and hydrogen (0–20 sccm H〈sub〉2〈/sub〉) additions into Ar atmosphere. The addition of acetylene resulted in the increase of carbon and hydrogen contents in the matrix via incorporation of C〈sub〉x〈/sub〉H〈sub〉y〈/sub〉 fragments with the C〈sub〉2〈/sub〉H, 2C and CH radicals being the “primary” source for growth. The level of hydrogenation in the carbon matrix was found to be related to the level of sp〈sup〉3〈/sup〉 hybridization and cross-linking as well. Hardness and coefficient of friction of the studied W-C:H coatings were found to be affected not only by hydrogenation and hybridization, but also by the sputtering technique. HiPIMS provided the best combination of hybridization, hydrogenation and cross-linking in the carbon structure resulting in W-C:H coatings with reasonably high (~20 GPa) hardness and simultaneously sufficiently low (≤0.1) coefficients of friction. Thus, HiPIMS applied to hybrid PVD-PECVD W-C:H coatings expands the range of their mechanical and tribological properties compared to DCMS and HiTUS.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): I. Campos-Silva, A.M. Delgado-Brito, J. Oseguera-Peña, J. Martínez-Trinidad, O. Kahvecioglu-Feridun, R. Pérez Pasten-Borja, D. López-Suero〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉New results about the tribocorrosion resistance of borided ASTM F1537 alloy immersed in Hank's solution were obtained in this study. A CoB-Co〈sub〉2〈/sub〉B layer, with around 30 μm of thickness, was obtained at the surface of the cobalt-based alloy using the powder-pack boriding process at 1273 K with 6 h of exposure. The tribocorrosion tests were carried out in the borided ASTM F1537 alloy and the non-borided ASTM F1537 alloy (reference material) using a linear reciprocating tribometer coupled with a standard three-electrode electrochemical cell. A counterpart of alumina (ball of 4.8 mm-diameter) was used, with a constant applied load of 20 N, and a total sliding distance of 100 m. The total material loss rate due to tribocorrosion (T), which included the mass loss rate due to wear (W) and that due to corrosion (C), was estimated according to the ASTM 〈a href="http://www.astm.org/Standards/G119" target="_blank"〉G119〈/a〉 procedure.〈/p〉 〈p〉The results showed that the presence of CoB-Co〈sub〉2〈/sub〉B layer at the surface of the ASTM F1537 alloy increased the tribocorrosion resistance around 1.2 times compared with the reference material. In addition, for the reference material, 55% of the material loss rate was attributed to the wear-corrosion synergism in comparison with 47% estimated for the borided ASTM F1537 alloy. Finally, the influence of wear affected in greater extent than corrosion in the reference material, whilst the corrosion-wear regime was obtained for the borided ASTM F1537 alloy.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): K. Bobzin, T. Brögelmann, C. Kalscheuer, T. Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Gas turbine engines operating in environments containing solid particles such as sand, dust and ice particles are challenged by the problem of solid particle erosion (SPE), which causes contour changes especially on compressor blades. Consequently, the performance and efficiency of the engines as well as the maintenance intervals will be reduced. In order to minimize the effects of SPE and to extend the lifetime of compressor blades, the application of erosion resistant coatings represents a promising way.〈/p〉 〈p〉In the present work, (Ti,Al,Si)N coatings were deposited onto martensitic steel X3CrNiMo13-4 used for compressor blades by the high speed physical vapor deposition (HS-PVD) technology. Morphology of the coatings investigated by scanning electron microscopy (SEM) shows a dense microstructure with coating thickness s 〉 11 μm. Owing to hollow cathode discharge (HCD) and the transport function of the plasma-forming gas Ar, which are specific in HS-PVD deposition processes, high deposition rates ds/dt 〉 11 μm/h were achieved. The coated samples were then post-annealed directly in the coating chamber with varying atmosphere such as in vacuum and in nitrogen with or without bias voltage induced Ar-plasma. The post-annealing effects on the microstructure, indentation hardness as well as chemical and phase compositions were investigated by SEM, glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD) and nanoindentation, respectively. The erosion resistance of annealed, as-deposited and uncoated samples was investigated using a fine sand blasting facility. Basing on measured mass change and inspection of the eroded surfaces, a significantly higher erosion resistance of the (Ti,Al,Si)N coated samples compared to uncoated substrates could be revealed. Moreover, the post-annealing process led to a further improvement of the erosion resistance. Therefore, the thick (Ti,Al,Si)N coatings deposited by HS-PVD in combination with post-annealing in N〈sub〉2〈/sub〉 atmosphere provide a high potential for the protection of compressor blades against SPE.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Gaurav Malik, Satyendra Mourya, Jignesh G. Hirpara, Ramesh Chandra〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research work, the synthesis and the electrochromic (EC) performance of the active material (γ-WO〈sub〉3〈/sub〉) is reported. Nanoporous γ-WO〈sub〉3〈/sub〉 thin film was grown directly on the indium tin oxide (ITO) coated glass substrate using DC magnetron sputtering in a reactive environment (Ar:O〈sub〉2〈/sub〉 = 2:1) at room temperature (RT). To achieve the nanoporous-nanocrystalline behaviour of the active material, a thermal treatment (250 °C) was given, which modified the compact film surface into nanospheres. This surface modification is responsible to alter the physical, optical and electrochromic properties of the active material. The physical properties of the active material were probed in detail using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and energy-dispersive X-ray analysis (EDX). The optical and electrochromic behaviour of the active electrode material was analyzed using UV–Vis spectroscopy and cyclic voltammetry (CV). It has been found that the modified electrode exhibited large optical modulation (46%), high reversible redox behaviour (higher current density) and good cyclic stability at least upto 500 cycles, causes scaled EC behaviour. This electrochemically active architecture allow one to fabricate the device for energy harvesting applications. Our work indorse human comfort with financial benefits and may play a crucial role in “green nanotechnology”.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Yu-Heng Liu, Li-Chun Chang, Bo-Wei Liu, Yung-I Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Monolithic and multilayered W〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N and W–Si–N coatings were fabricated through direct current magnetron cosputtering at substrate holder rotation speeds of 0 and 5 rpm. The mechanical properties, structural evolutions, and oxidation behaviors of the W〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N and W–Si–N coatings were investigated through nanoindentation, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. The mechanical properties of crystalline W〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N coatings correlated to their textures and residual stresses. The monolithic W〈sub〉77〈/sub〉N〈sub〉23〈/sub〉 samples located closest to the W target exhibited a high deposition rate of 18.0 nm/min, a strong (200) texture coefficient, a high nanoindentation hardness of 32.7 GPa, a high Young's modulus of 392 GPa, and a high residual stress of −3.2 GPa. The addition of Si into the W〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉N matrix transformed the monolithic W–Si–N coating into an X-ray amorphous phase dominated structure that comprised Si〈sub〉3〈/sub〉N〈sub〉4〈/sub〉, W〈sub〉2〈/sub〉N, and W constituents. Ion bombardment caused the formation of multilayered W〈sub〉78〈/sub〉N〈sub〉22〈/sub〉 samples with high residual stress and mechanical properties. The mechanical properties and residual stresses of the multilayered W–Si–N coatings decreased due to the preferential formation of Si〈sub〉3〈/sub〉N〈sub〉4〈/sub〉. By contrast, oxidation resistance was improved by adding Si content higher than 24 at.% with annealing at 600 °C in a 1% O〈sub〉2〈/sub〉–99% Ar atmosphere.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): M. Mohammadtaheri, Y. Li, J. Corona-Gomez, Q. Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coatings with superior hardness, high temperature thermal stability, and oxidation resistance are required to protect cutting tools in machining applications. Hence, the synthesis of such coatings was investigated in a ternary Cr–Zr–O system by reactive radio-frequency magnetron sputtering technique. For this purpose, the Cr–Zr–O coatings with chemical compositions up to 9 at. % Zr were deposited on Si (100) substrates. The coatings were then characterized by energy dispersive spectroscopy, X-ray diffraction, Raman spectroscopy, and Nanoindentation and a correlation between their chemical composition, crystal structure, phase composition, and mechanical properties was established. The structural stability of the coatings was also evaluated after annealing treatments. The results indicated that adding zirconium to Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 coatings shifted the onset of crystallization for the coatings to higher temperatures. The hardness measurements showed that Cr-Zr-O coatings have the potential to reach a hardness value over 40 GPa. Based on the XRD and Raman spectroscopy analysis, it was assumed that grain size refinement and solid solution hardening were the most responsible mechanisms for the enhanced hardness. Annealing treatments at elevated temperatures showed that the thermal stability of the superhard Cr-Zr-O coatings was higher than pure chromium oxide coatings. Moreover, the metastable (Cr, Zr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 structure in the superhard coatings decomposed to Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and ZrO〈sub〉2〈/sub〉 phases at 1000 °C, indicating that Zr has 〈2 at. % solubility in Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 in an equilibrium condition.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Paola Luchtenberg, Paulo Tancredo de Campos, Paulo Soares, Carlos Augusto Henning Laurindo, Ossimar Maranho, Ricardo Diego Torres〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Duplex stainless steels (DSS) show good mechanical properties, wear, corrosion resistance and fatigue strength. In order to decrease operational costs in paper and pulp industry, DSS is employed through weld overlay coatings on mild or low carbon steel components. In this work, the aim was to evaluate the DSS weld overlay properties obtained through deposition of ER 2209 duplex stainless steel alloy on a mild steel plate (ASTM A 516 Gr 60). The deposition was performed through GMAW/CMT welding process. The coatings were deposited using four heat inputs: 0.53, 1.01, 1.27 and 1.74 kJ/mm. Moreover, microstructural characterization by optical microscopy showed that heat input influences ferrite/austenite phase balance. Secondary austenite that precipitates due to the welding process in DSSs are Widmanstätten austenite (WA), grain boundary austenite (GBA), partially transformed austenite (PTA) and intragranular austenite (IGA). The amount of secondary austenite increases with welding energy input. The secondary austenite improves abrasive wear resistance while corrosion resistance is the lowest when welding energy is 1.74 kJ/mm.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Jiawei Jiang, Gui Han, Xuesong Zheng, Gang Chen, Peizhi Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, we prepared a layer of hydroxyapatite (HA) coating on the surface of titanium alloy 〈em〉via〈/em〉 hydrothermal process. FTIR, SEM, Raman, XRD and electrochemical tests were used to analyze the structure of prepared HA coating. The prepared HA coating on the surface of titanium alloy demonstrated superior corrosion resistances. Antibacterial experiments proved that HA coating could adsorb drugs and act as a carrier for antibiotics to achieve inhibition of bacteria. The experimental results indicated that HUVEC cells could adhere to the surface of substrates. Animal experiments also confirmed that HA coating has good biocompatibility and promote the formation of new bone.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Adrian Chlanda, Przemysław Oberbek, Marcin Heljak, Żaneta Górecka, Katarzyna Czarnecka, Ko-Shao Chen, Michał J. Woźniak〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biodegradable 3D-printed polycaprolactone scaffolds for bone tissue engineering applications have been extensively studied as they can provide an attractive porous architecture mimicking natural bone, with tunable physical and mechanical properties enhancing positive cellular response. The main drawbacks of polycaprolactone-based scaffolds, limiting their applications in tissue engineering are: their hydrophobic nature, low bioactivity and poor mechanical properties compared to native bone tissue. To overcome these issues, the surface of scaffolds is usually modified and covered with a ceramic layer. However, a detailed description of the adhesion forces of ceramic particles to the polymer surface of the scaffolds is still lacking. Our present work is focused on obtaining PCL-based composite scaffolds to strengthen the architecture of the final product. In this manuscript, we report qualitative and quantitative evaluation of low temperature plasma modification followed by detailed studies of the adhesion forces between chemically attached ceramic layer and the surface of polycaprolactone-nanohydroxyapatite composite 3D-printed scaffolds. The results suggest modification-dependent alteration of the internal structure and morphology, as well as mechanical and physical scaffold properties recorded with atomic force microscopy. Moreover, changes in the material surface were followed by enhanced adhesion forces binding the ceramic layer to polymer-based scaffolds.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Frederico Goncalves de Cerqueira Lima, Ulrich Mescheder, Harald Leiste, Claas Müller〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrodeposition of metals directly on non-metal substrates without any seed layer reduces process steps; however, adhesion of the electrodeposited layer is a challenge. In this work, the influence of current density during seedless electroplating on the adhesion of Cu layers on Si substrates was investigated. Cu was electrodeposited on phosphorus-doped Si samples having different orientations in two stages. During the first stage, higher current densities were used for a few minutes to reach instantaneous nucleation and maximize the number of Cu islands on the substrate. The second stage had the goal of growing the nuclei previously formed. Therefore, lower current densities were used to create progressive nucleation. Adhesion values of Cu layers on Si were derived from scratch tests and tensile measurements. Higher adhesion was obtained either at higher current densities or at lower cathodic potentials at the beginning of potentiostatic or galvanostatic processes. To study the influence of hydrogen evolution on the adhesion of seedless electrodeposited Cu on Si, the transition time which indicates the moment when transferred charges are used to create hydrogen at the cathode, was determined experimentally. The transition time shows a strong dependence on current density. Therefore, control and optimization of adhesion by an appropriate choice of current densities within the two-stage process is possible.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Chenglong Ma, Dongdong Gu, Donghua Dai, Han Zhang, Hongmei Zhang, Jiangkai Yang, Meng Guo, Yuexin Du, Jie Gao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, TiC ceramic particle reinforced TiAl-based composites were synthesized by selective laser melting (SLM) by using Ti, Al, and TiC multi-component powder. The results showed that a plenty of TiC dendritic crystals formed during the solidifying process. It was found that TiC dendrites exhibited three different modes of nucleation and growth, corresponding to the dissolution-precipitation of fully melted fine TiC particles, the epitaxial growth along the margin of partly melted TiC particle, and the recrystallization growth based on stress-induced nonequilibrium melting. Subsequently, the influence of laser energy density on microstructure evolution and high-temperature oxidation behaviour of SLM fabricated TiC/TiAl composites were investigated. At a high laser energy density of 189 J/mm〈sup〉3〈/sup〉, the relatively full dense SLM-fabricated part was obtained, accompanying the formation of a variety of TiC dendrites with the coarsening structure, which made a contribution to the elevated high-temperature oxidation resistance with a low oxidation kinetics constant of 1.32 × 10〈sup〉−〈/sup〉〈sup〉5〈/sup〉 mg 〈sup〉6〈/sup〉 cm〈sup〉−〈/sup〉〈sup〉12〈/sup〉 h〈sup〉−〈/sup〉〈sup〉1〈/sup〉.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219307996-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): A.P. Rubshtein, K. Gao, A.B. Vladimirov, S.A. Plotnikov, B. Zhang, J. Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The structures, wear resistances, and corrosion behaviours of Cr–Al–C and multilayer [Cr–Al–C/a-C]〈sub〉〈em〉n〈/em〉〈/sub〉 coatings, fabricated by physical vapour deposition (PVD), plasma-assisted chemical vapour deposition (PACVD), or their combination, were studied. A Cr〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Al target served as a source of chromium and aluminium, while a graphite target or acetylene served as sources of carbon. Depending on the type of carbon source, Cr–Al–C or Cr–Al–C(H) coatings were obtained. Multilayer [Cr–Al–C/a-C]〈sub〉20〈/sub〉 and [Cr–Al–C(H)/a-C:H]〈sub〉20〈/sub〉 coatings were fabricated by alternating pair layers of [Cr–Al–C (PVD)/a-C (PVD)] and [Cr–Al–C(H) (PVD–PACVD)/a-C:H (PACVD)], respectively. a-C and a-C:H are hydrogen-free and hydrogenated diamond-like carbons. X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy were employed to investigate the coating structures. Along with the amorphous matrix, chromium carbide, and Cr〈sub〉〈em〉x〈/em〉〈/sub〉Al〈sub〉1-〈em〉x〈/em〉〈/sub〉C nanograins, clusters of nanocrystalline graphite as spherical inclusions and plates, probably of several graphene layers, were observed in Cr–Al–C. This structure provided high hardness and corrosion resistance. Along with the amorphous matrix, Cr〈sub〉2〈/sub〉AlC and chromium carbide nanoclusters and clusters of nanoscale CVD diamond with wide boundaries of sp〈sup〉2〈/sup〉-bonded carbon were observed in Cr–Al–C(H), whose hardness did not exceed 8.9 GPa. The multilayer structures significantly increased the wear resistances. The specific coefficient of wear rate (SCWR) of [Cr–Al–C/a-C]〈sub〉20〈/sub〉 was five times lower than that of Cr–Al–C. Hybrid PVD–PACVD technology provided favourable conditions for the formation of wear-resistant coatings. The SCWR of [Cr–Al–C(H)/a-C:H]〈sub〉20〈/sub〉 was 47 times lower than that of [Cr–Al–C/a-C]〈sub〉20〈/sub〉. The high wear resistance of the multilayer coatings was associated with the structure, low friction coefficient, high crack resistance, and strengthened interface boundaries.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219308849-ga1.jpg" width="232" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Sergio Pinilla, Teresa Campo, José María Sanz, Francisco Márquez, Carmen Morant〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Highly ordered metal porous membranes containing Fe and Zr in different layers have been fabricated by successive ion-beam sputtering depositions of these metals onto a porous anodic aluminum oxide (AAO) membrane. Two different membrane configurations were studied: Zr/Fe/AAO and Fe/Zr/AAO. Morphology and composition of these multi-membranes have been characterized by Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and Rutherford Backscattering Spectrometry (RBS). The RBS analysis allowed a precise quantification of the atomic composition of the metal membrane and the support layer. The asymmetry and long tails observed for the metallic peaks in the RBS spectra indicate the different filling of the pores during the deposition. These results provide a possible structural configuration for the metal membranes, where Fe/Zr/AAO and Zr/Fe/AAO membranes follow different behaviors.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): A.H. Abdelhameed, W. Jacob〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermally stable tungsten nitride (〈em〉W〈/em〉〈sub〉2〈/sub〉〈em〉N〈/em〉) thin films with thickness ∼ 0.9 μm were successfully deposited on 〈em〉Si〈/em〉 and graphite substrates by reactive magnetron sputtering. The produced layers show no phase change or nitrogen release up to 1300 K. These novel layers survived annealing at 1200 K for 50 h without any measurable nitrogen loss or a phase transition from 〈em〉W〈/em〉〈sub〉2〈/sub〉〈em〉N〈/em〉 to 〈em〉bcc W〈/em〉. X-ray diffraction, thermal desorption spectroscopy and Rutherford back scattering were utilized to characterize these layers and investigate the nitrogen release mechanism. The micro-structure of the layers was dominated by a grainy structure with porosity less than 16〈em〉%〈/em〉 and a strong texture in (200) orientation in contrast to the common (111) orientation. For annealing temperatures higher than 1200 K nitrogen release was observed, but this was attributed to a chemical reaction of 〈em〉W〈/em〉〈sub〉2〈/sub〉〈em〉N〈/em〉 with the substrate material(s).〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Xiao-feng Zhang, Yu-xiao Cui, Xi-bei Liu, Tian-yi Sui, Chun-hui Ji, Da-wei Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The wettability of nano-crystalline diamond (NCD) films is of great importance to their bio-functional applications. In this work, the wettability of NCD films is controlled by two types of in-situ CVD process, namely oxygen doping and water vapor etching (WVE). Field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), micro-Raman spectroscopy, X-ray diffraction spectroscopy (XRD) and X-ray photoelectron spectroscopy (XPS) are performed to characterize as-fabricated NCD specimens. The oxygen doping and WVE have a significant effect on the surface topography and chemical termination of NCD films respectively, which can alter their wetting properties. Angle contact measurements show that the wettability of NCD films can be modulated from weak hydrophobic to either very hydrophobic (contact angle of 140.1°) or super-hydrophilic (contact angle of 0°).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Xiaowei Zhou, Yuxin Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For increasing the interfacial bonding of Ni deposits onto Ti surface, the objectives of this work are to explore an effective approach for LaCl〈sub〉3〈/sub〉-modified Ni nanocrystals on porous surface of Ti substrate. Three-dimensional (3D) heterotypic nanopores were well organized with a diameter size of ~300 nm through surface anodizing in H〈sub〉3〈/sub〉PO〈sub〉4〈/sub〉-containing acid solution at DC 180 V. In view of the above considerations, the anodized surface with a 3D-open reticular structure was processed of high adsorption capacity leading into pitting growth of Ni crystals into 3D-pores. Experimental data have referred that a leaf-like surface with the diversified orientations of Ni (111) (200) (220) (311) facets were conducted for Ni-LaCl〈sub〉3〈/sub〉 deposits instead of an exclusive growth of Ni (111) (200) facets for pure Ni. Based on Nanoindentation tests, it exhibited the ratio of micro hardness (〈em〉H〈/em〉〈sup〉3〈/sup〉) and elastic modulus (〈em〉E〈/em〉〈sup〉2〈/sup〉) of Ni samples remarkably increased with increasing LaCl〈sub〉3〈/sub〉 addition from 0 to 2.0 g/L. As excepted, the steady-state friction coefficient was ~0.28 for Ni-2.0 g/L LaCl〈sub〉3〈/sub〉 composites, which was about one order of magnitude lower than that of pure Ni sample during oxidized at 500 °C in air. The exceptional improvements of corrosion resistance for LaCl〈sub〉3〈/sub〉-modified Ni deposits were associated with the co-existence of high adsorptive La〈sup〉3+〈/sup〉 ions and the La-rich insoluble corrosive products in 1 M (mol/L) HCl solution. In light of this, Ni-based nanocomposites on 3D-heterotypic porous surface of Ti alloys would provide an effective guidance for protecting Ti alloys against wear and corrosive damages.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219308035-ga1.jpg" width="274" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): V. Malinovschi, A. Marin, V. Andrei, E. Coaca, C.N. Mihailescu, Cristian P. Lungu, Cristiana Radulescu, Ioana Daniela Dulama〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Phosphorus-incorporated oxide layers were grown on commercially pure titanium during plasma electrolytic oxidation in sodium dihydrogen phosphate dihydrate solution. Microstructure, mechanical and electrochemical behavior of the surface oxides indicated a dominant anatase and rutile structure of TiO〈sub〉2〈/sub〉 with nanocrystallites ranging from 45 to 64 nm and 48–98 nm, respectively as well as Ti〈sup〉2+〈/sup〉, Ti〈sup〉3+〈/sup〉 and Ti〈sup〉4+〈/sup〉 chemical species. Using a combination of process time, applied current and electrolyte concentration, coating thicknesses up to about 10 μm were fabricated. Best mechanical performance was observed for potentiostatic deposited samples yielding a 453 HV〈sub〉300〈/sub〉 hardness, 19 N adhesive failure and 38 N full delamination resistance. All PEO-coated samples in this work exhibit a corrosion current density with one order of magnitude lower than CP-Ti when subjected to Ringer's physiological solution.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Zhijun Li, Qing Kuang, Xiuli Dong, Tongwei Yuan, Qinghui Ren, Xuexia Wang, Jun Wang, Xiaoyan Jing〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High-performance anti-corrosion/anti-wear coatings on superlight magnesium‑lithium (Mg〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Li) alloy with exceptional durability are of great interest for fundamental research and practical applications. In the present study, oxide coatings are produced on Mg〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Li alloy by electrochemical surface engineering––plasma electrolytic oxidation in an alkaline silicate electrolyte with addition of cerium salt. To understand the nature of coatings, we investigate their surface and cross-sectional morphologies, wettability (35 ± 3° 〈em〉vs〈/em〉 78 ± 2°), phase and chemical compositions, corrosion and tribological behaviors. Our findings show that the oxide coating prepared with cerium salt has a more compact structure with fewer defects (18 μm in thickness). Importantly, it substantially enhances the corrosion resistance of Mg〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉Li alloy by three orders of magnitude and significantly retards the occurrence of localized corrosion (150 h), along with notably improved anti-wear performance (friction coefficient of 0.19).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): B. Hadzima, F. Pastorek, K. Borko, S. Fintová, D. Kajánek, S. Bagherifard, M. Gholami-Kermanshahi, L. Trško, J. Pastorková, J. Brezina〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Shot peening is a standard surface treatment primarily used for enhancement of fatigue properties of metallic materials. However, its influence on surface properties is so radical, that subsequent techniques of surface treatment used on the shot peened surface need to be reconsidered in order to minimize the possible negative side effects of shot peening. In this case, the differences between hurealite formation on the ground and shot peened surfaces of modern high strength low alloy (HSLA) steel were evaluated by morphological and electrochemical corrosion observations and measurements. The surface morphologies of the formed coatings were observed by the scanning electron microscopy (SEM) and analysed by energy-dispersive X-ray analysis (EDX). The corrosion resistance of the HSLA steel with hurealite coating was evaluated using electrochemical impedance spectroscopy (EIS) by the analysis of Nyquist plots obtained in 0.1 M NaCl solution after various phosphating times on both types of pre-treated surfaces (ground and shot peened). The results showed that used technique of shot peening negatively influenced the phosphating process by prolonging the phosphating process in order to reach the coating with maximal protection properties in tested medium. Moreover, shot peened surface caused significantly enlarged size of the hurealite crystals and greater thickness of the coating compared to the surface pre-treated by grinding on the tested HSLA steel at the expense of a lower compactness and corrosion protection.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219307960-ga1.jpg" width="499" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Hang Li, Jianliang Li, Zhaoli Liu, Jiewen Huang, Jian Kong, Dangsheng Xiong〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ternary transition metal nitrides have procured wide attention towards practical application due to their high hardness, wear resistance and thermal stability. In this study, Hf〈sub〉1-x〈/sub〉Mo〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 thin films are deposited by reactive direct current magnetron sputtering (R-DCMS) system in an effort to improve further the properties of their analogous binary compounds. In addition, the influence of Mo content on the structure, mechanical and tribological properties of the films are also investigated. The composition and microstructure of the as-deposited Hf〈sub〉1-x〈/sub〉Mo〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 films are characterized by X-ray diffraction, Raman and scanning electron microscopic techniques. Spectroscopic results show that, as-sputtered Hf〈sub〉1-x〈/sub〉Mo〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 films mainly consist of single solid solution phase with rock-salt structure. Ultra-micro hardness and ball-on-disc wear tests are conducted to evaluate the mechanical and tribological properties of Hf〈sub〉1-x〈/sub〉Mo〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 films. The toughness Hf〈sub〉1-x〈/sub〉Mo〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 films are enhanced, and the film with x = 0.589 shows better mechanical properties, meanwhile, the lowest wear rate of 0.57 × 10〈sup〉−〈/sup〉〈sup〉6〈/sup〉 mm〈sup〉3〈/sup〉/Nm, which is two order magnitudes lower than corresponding binary compounds viz., δ-HfN and γ-Mo〈sub〉2〈/sub〉N, and lowest friction coefficient of 0.35 are also obtained. This could be attributed to the effect of solution reinforcement and valence electron concentration. The unique wear resistance of Hf〈sub〉1-x〈/sub〉Mo〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 is ascribed to the outstanding oxidation resistances and higher H/E and H〈sup〉3〈/sup〉/E〈sup〉2〈/sup〉 values, which indicate the mechanical properties, wear resistance and anti-friction of δ-HfN and γ-Mo〈sub〉2〈/sub〉N can be improved by alloying with each other.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Abhay Gupta, Chandan Srivastava〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present study, microstructure-electrochemical property correlation in electrodeposited SnBi-GO composite coatings containing different amounts of graphene oxide has been investigated. The SnBi-GO coatings exhibited uniform and compact morphology for lower GO concentrations, whereas for higher GO concentrations the morphological defects appeared. X-ray diffraction analysis showed the presence of Sn rich and a Bi rich phase in the coatings. Crystallite size of Bi-rich phase decreased whereas for Sn-rich phase it remained nearly unaffected with increasing GO addition. Growth texture analysis showed that the incorporation of GO enhanced growth along the low index planes for the Sn-rich grains and along the high index planes for the Bi-rich grains. Corrosion properties of coatings examined by the potentiodynamic polarisation and impedance spectroscopy methods revealed that the corrosion rate of the coatings decreased with increase in the GO content till an “optimum” addition of GO, after which the corrosion rate significantly increased with further GO addition. Microstructural analysis conducted using the electron backscatter diffraction (EBSD) technique showed that the coating with “optimum” GO amount which yielded the minimum corrosion rate contained highest fraction of low energy low angle grain boundaries which was due to the lowering of Bi dissolution in the Sn grains. Initial decrease in the corrosion rate was attributed to coating compactness, growth of grains along low energy index planes and GO impermeability. Increase in the corrosion rate after the optimum was attributed to increase in the morphological defects and possible galvanic coupling between the GO and the metals in the coatings. The enhanced corrosion properties of SnBi-GO coatings make them a viable material for interconnections used in the electronic components.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S025789721930800X-ga1.jpg" width="344" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Ziai Liu, Xiaolong Yang, Guibing Pang, Fan Zhang, Yuqi Han, Xuyue Wang, Xin Liu, Lin Xue〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Superhydrophobic surfaces with tunable water adhesion and adjustable wettability have the capacity to manipulate water droplets under complicated conditions and, therefore, have great prospects in various domains. Hence, developing a facile method to prepare highly stable superhydrophobic surfaces with tunable water adhesion and adjustable wettability is of great importance. Herein, we prepare the superhydrophobic aluminum surface by combining laser etching and stearic acid modification. The variations of water contact angle, water sliding angle and water adhesive force with temperature of the prepared surface are characterized during the adhesion tuning process to investigate its temperature-responsive characteristics. A low/high adhesion switching of water on the prepared surface is subsequently achieved under alternating temperature. In addition, a facile approach is designed to achieve the superwettability switching process (from superhydrophobic state to superhydrophilic state) on the prepared surface. The prepared superhydrophobic surface displays excellent recoverability, stability and repeatability in the adhesion switching process and the superwettability switching process, even after being cycled for 10 times.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S025789721930773X-ga1.jpg" width="416" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): E. Ura-Bińczyk, A. Krawczyńska, R. Sitek, M. Lewandowska〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effect of nitriding on the surface structure, mechanical properties and corrosion resistance of hydrostatically extruded 316 LVM stainless steel was evaluated and compared with coarse grained counterpart. Hydrostatic extrusion was performed at either room or elevated temperature and resulted in microstructure refinement. Nitrided layers of a similar thickness were formed on the samples irrespective of their microstructure. The nitriding process was performed at 430 °C for 5 h. The processing conditions did not affect the bulk mechanical properties of the micro and HE processed samples and their mechanical strength remained unchanged after nitriding. The electrochemical measurements revealed that the nitrided hydrostatically extruded 316 LVM steels had better corrosion resistance than their microcrystalline counterpart.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Prashant Huilgol, K. Rajendra Udupa, K. Udaya Bhat〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The microstructure of the hot-dip aluminized AISI 321 stainless steel was studied after diffusion treatment at 900 °C for 3 h. The microstructural characterization was carried out by scanning electron microscopy, transmission electron microscopy, and X-ray diffractometry. The microstructure of the as aluminized steel consisted of two regions, viz.; aluminum topcoat and aluminide layer. During the diffusion treatment, the coating transformed into a layered structure consisting of four layers. The Fe〈sub〉2〈/sub〉Al〈sub〉5〈/sub〉 phase was formed in the outermost layer and the presence of Al〈sub〉13〈/sub〉Fe〈sub〉4〈/sub〉 quasicrystalline approximant phase was observed. The innermost layer adjacent to the base metal transformed to ferrite phase with NiAl precipitates. Next, to this layer, a disordered FeAl phase was observed. The lattice parameter of the disordered FeAl phase was found to be larger than that of the ordered B2 FeAl phase. The layer between outer Fe〈sub〉2〈/sub〉Al〈sub〉5〈/sub〉 phase and disordered FeAl phase consists of a mixture of three phases, namely Fe〈sub〉2〈/sub〉Al〈sub〉5〈/sub〉, disordered FeAl and a new phase with the simple cubic structure. The phase with simple cubic structure shares cube on cube crystallographic orientation relationship with the disordered FeAl phase.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Elbert Contreras Romero, Joan Cortínez Osorio, Roberto Talamantes Soto, Abel Hurtado Macías, Maryory Gómez Botero〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Four nanostructured TiAlTaN-(TiAlN/TaN)〈sub〉n〈/sub〉 coatings were deposited, varying the volume fraction of the top quaternary coating (TiAlTaN) and the base multilayer coating (TiAlN/TaN) with percentages of: 84/16, 66/34, 48/52 and 23/77, and evaluating their effect on mechanical and tribological performance of the nanostructured coatings. The cross-sectional images obtained by FE-SEM showed the interface between each of the constituent monolayer, a well-defined columnar structure for the TiAlN/TaN multilayer coating, while in the quaternary TiAlTaN coating thicker columns were also observed. High-resolution TEM analysis revealed well-defined multilayer architecture followed by the quaternary TiAlTaN. The nanostructured TiAlTaN-(TiAlN/TaN) coatings showed preferential growth in the direction (111) corresponding to the rock-salt-like crystalline structure of the TiN. Additionally, the shift of this peak was observed as the volume fraction of TiAlTaN decreased, associated to the decrease in the residual stresses of the coatings. Regarding tribological properties, nanostructured coatings exhibited relatively high friction coefficients (~0.8) for coatings with higher TiAlTaN volume fraction, with a clear progressive decrease as the volume fraction of multilayer TiAlN/TaN coatings increases. The high friction coefficients are compensated by the low wear rates of coatings compared to the uncoated substrate. Regarding to the mechanical properties, nanostructured coatings, follow the composite rule of mixtures, with a hardness between 32 GPa (TiAlTaN) and 25 GPa (TiAlN/TaN), Young's modulus showed similar behavior. The coatings adhesion increased progressively as the percentage of TiAlN/TaN increased, reaching L〈sub〉c3〈/sub〉 values higher than 28 N. The propagation of the transverse and longitudinal crack were observed by FE-SEM, in radial direction to the direction of application of the load and oblique direction with 45° tangential to the direction of scratching, respectively.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): J.A. Lenis, G. Bejarano, P. Rico, J.L. Gómez Ribelles, F.J. Bolívar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The use of composite coatings is emerging as a great alternative to conventional coatings, allowing the combination of different superficial properties that are widely desired in surgical implants, such as osteointegration and bactericidal character, and cannot be provided by one material alone. In the present investigation the effect of the incorporation of a TiN-Ti intermediate bilayer on the chemical composition, structure, morphology, roughness, residual stresses and adhesion of a multi-layer Hydroxyapatite (HA)-Ag coating deposited on Ti-6Al-4V by magnetron sputtering was evaluated. Additionally, the cytotoxicity of the developed system was evaluated by in vitro tests. According to the results obtained, a decrease in the Ca/P ratio from 1.85 to 1.74 was obtained through the deposition of an HA-Ag system on the intermediate bilayer, and the crystallinity of the developed coating was favored. The multi-layer structure was effectively observed by field emission scanning electron microscopy, where it was possible to identify each of the HA, Ag, TiN and Ti layers. Meanwhile, an increase of 7% in crystallite size, a decrease of 36% in residual stresses and an increase of 32% in adhesion were registered for this composite coating compared to the free intermediate bilayer system. Finally, biological evaluation allowed the non-cytotoxic character of the deposited coatings to be confirmed.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 15 August 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): Peng Zhou, Yang Liu, Lianhe Liu, Baoxing Yu, Tao Zhang, Fuhui Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, different pretreatment condition on AA6061 was investigated by altering the alkaline cleaning time in NaOH, the concentration and composition of acidic pickling solution, respectively. The corrosion resistance of ZrCC was evaluated, and the surface property of the pretreated surface was measured by SKPFM. Results demonstrate that a longer alkaline cleaning time is detrimental to the corrosion resistance of ZrCC since it will decrease the Volta potential difference (ΔE); the acidic pickling in HNO〈sub〉3〈/sub〉 improves the corrosion resistance of ZrCC, but an increased concentration will not remarkably further improve the quality of ZrCC, due to the accompanying of increased ΔE; the addition of HF will lead to the overactivation of alloy surface since it will decrease ΔE and increase ΔH. An ideal pretreated surface shown exhibit a combination of mediate ΔH and high ΔE.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 November 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 377〈/p〉 〈p〉Author(s): Tianshi Hu, Zhijun Shi, Wei Shao, Xiaolei Xing, Yefei Zhou, Qingxiang Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The differential charge density and density of states used to analyze the bonding of atoms at the interface, the interface adhesion and spreading coefficient of the interface were calculated by first principle method. Ni-Cr-WC and Ni-Cr-WC-CeO〈sub〉2〈/sub〉 wear resistant coatings were prepared by sintering method. The density of the coatings was measured. The morphology and elemental distribution of the coatings were observed and analyzed by the scanning electron microscope. The wear scratch morphology was observed and measured by the white confocal microscope, and the wear volume was fitted. The results of differential charge density and density of states show that there are polar covalent bonds and metal bonds at the Ni/CeO〈sub〉2〈/sub〉 interface, so the wetting tendency of Ni and CeO〈sub〉2〈/sub〉 is poor. The interfacial adhesion work is −1.63 ev/Å〈sup〉2〈/sup〉, and the spreading factor is 14.63 ev/Å〈sup〉2〈/sup〉. It indicates that Ni atoms could not spontaneously wet on the surface of CeO〈sub〉2〈/sub〉, which can improve the density of the Ni-base coating. The experimental results show that CeO〈sub〉2〈/sub〉 is distributed in the matrix of the coating. The large pores in the coating disappear, and the density of the coatings is increased from 99.89% to 99.92%. The wear volume of the coating is decreased from 14.56 × 10〈sup〉6〈/sup〉 μm〈sup〉3〈/sup〉 to 7.31 × 10〈sup〉6〈/sup〉 μm〈sup〉3〈/sup〉, which indicates that the wear resistance of the coating with CeO〈sub〉2〈/sub〉 is improved.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): A. Michau, Y. Gazal, F. Addou, F. Maury, T. Duguet, R. Boichot, M. Pons, E. Monsifrot, H. Maskrot, F. Schuster〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Direct liquid injection – metalorganic chemical vapor deposition (DLI-MOCVD) is the most advanced process dedicated to the internal protection of nuclear fuel cladding in accident conditions such as loss of coolant. It allows the deposition of an amorphous, glassy-like chromium carbide CrC〈sub〉x〈/sub〉 coating which is resistant against high-temperature oxidation in air and steam. Since the above-mentioned material characterizations demonstrated that coatings possessed the appropriate protection properties, the DLI-MOCVD process was scaled-up.〈/p〉 〈p〉First, a joint development between experimental and numerical studies led to a deposition inside a 1 m long cladding segment with a coating of sufficiently large and uniform thickness. Optimized reactor parameters consist in a combination of low temperature (~600 K) and low pressure (~600 Pa) with a high vapor flow rate of reactive species in the reactor ensuring a short residence time. The second phase of the scale-up consisted in coating simultaneously three, then sixteen segments in a single run. 3D computational simulations of the deposition process assisted the development of specific flanges designed to distribute homogeneously the reactive vapor into the three or sixteen cladding tubes. Experimental conditions have been extrapolated from one to three and to sixteen cladding segments, resulting in the deposition of the CrC〈sub〉x〈/sub〉 coating inside all segments with a relatively uniform partition.〈/p〉 〈p〉Overall, this paper demonstrates the feasibility of the deposition of CrC〈sub〉x〈/sub〉 coating in a bundle of several, up to sixteen, nuclear fuel cladding segments of 1 m in length (ID 8 mm), in order to protect them during accident conditions. This “batch demonstration” is a first step in the course of DLI-MOCVD technological transfer. Next step will be the deposition in a full-length cladding tube (4 m) that is already supported by numerical predictions.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Sheng-Bo Hung, Chaur-Jeng Wang, Yen-Yu Chen, Jyh-Wei Lee, Chia-Lin Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High entropy alloys (HEAs) have drawn lots of attentions from researchers and industries because of their outstanding properties, such as high hardness, and good corrosion resistance. Particularly, the refractory high entropy alloy is characterized by its high temperature strength and stable thermal properties. We conducted the magnetron co-sputtering process to grow one V-Nb-Mo-Ta-W and three V-Nb-Mo-Ta-W-Cr-B refractory HEA coatings. The BCC phase of V-Nb-Mo-Ta-W HEA coating was changed into the amorphous-like structures when Cr and B elements were added into the coatings. Oxidation reactions occurred and very complex refractory metal oxides were produced on all HEA coatings when the oxidation was held at 800 °C in air for 1 h. The addition of Cr and B constituents into the V-Nb-Mo-Ta-W coating can provide good oxidation resistance and anti-corrosion performance. The highest hardness of 18.4 ± 0.5 GPa, an excellent corrosion resistance at room temperature, a high hardness of 15.9 ± 1.1 GPa and good thermal stability after 500 °C oxidation test were obtained for the V〈sub〉10.4〈/sub〉Nb〈sub〉10.5〈/sub〉Mo〈sub〉10.5〈/sub〉Ta〈sub〉11.2〈/sub〉W〈sub〉10.5〈/sub〉Cr〈sub〉16.3〈/sub〉B〈sub〉28.6〈/sub〉 refractory HEA coating in this study.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 October 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 375〈/p〉 〈p〉Author(s): Athanasios Mourlas, Eleni Pavlidou, George Vourlias, Jose Rodríguez, Pandora Psyllaki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present work constitutes the second part of a study concerning the application of Concentrated Solar Energy (CSE) for the in-situ elaboration of carbide-reinforced surface layers onto common steels, employing WC as a model system. As in the first part that involved titanium and chromium carbides as reinforcing compounds, “solar hardfacing” experiments were carried out in the solar furnace SF40, at the installations of 〈em〉Plataforma Solar de Almería〈/em〉 (Spain). Parametric studies performed were targeted to clarify the effects of solar irradiation time and inert or reactive processing atmosphere on the structural integrity, microstructure, carbide dispersion and hardness of the surface layers obtained. The results were used, on the one hand to identify conditions for the elaboration of wear resistant surface layers and on the other hand to elucidate the fundamental mechanisms governing the dispersion of WC particles in a liquid ferrous matrix that is, subsequently, re-solidified. In contrast to the TiC particles, WC ones are subjected to liquid metal attack transforming progressively to mixed Fe〈img src="https://sdfestaticassets-eu-west-1.sciencedirectassets.com/shared-assets/16/entities/sbnd"〉W carbides, as determined by scanning electron microscopy and X-ray diffraction. Under inert atmosphere, solar processing beyond a threshold time period decreases the in-depth homogeneity of the carbides dispersion and increases the extent of the attack, deteriorating hence the composite character of the layer obtained. Reactive nitrogen atmosphere mitigates the negative effects of prolonged exposure, allowing the elaboration of thick hardfacing layers. Finally, dry sliding friction tests allowed defining the friction coefficient and specific wear rate, as well as the synergy of the wear micro-mechanisms involved. These results complemented with the respective ones for titanium and chromium carbide-based hardfacing layers, provide a first framework for the rational and optimized elaboration of wear resistant carbide-based surface layers using concentrated solar energy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Cristina Domínguez-Trujillo, Ana M. Beltrán, Maria D. Garvi, Alba Salazar-Moya, Julián Lebrato, Daniel J. Hickey, Jose A. Rodríguez-Ortiz, Paul H. Kamm, Clara Lebrato, Francisco García-Moreno, Thomas J. Webster, Yadir Torres〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, bacterial behavior on dense and porous titanium substrates is discussed. Porous titanium was fabricated by a space holder technique (using 50 vol%, NH〈sub〉4〈/sub〉HCO〈sub〉3〈/sub〉 with particle sizes between 250 and 355 μm). These substrates were coated by sulfonated PEEK (termed SPEEK). Characterization of the porous substrate was carried out using the Archimedes Method, Image Analysis, and three-dimensional X-ray Micro-Computed Tomography (including total and interconnected porosity, equivalent diameter, and pore shape factor), as well as mechanical characterization (specifically stiffness and yield strength). A detailed study was performed here to investigate the influence of substrate porosity on the adhesion and proliferation of 〈em〉E. coli〈/em〉, 〈em〉MRSA〈/em〉, and 〈em〉P. aeruginosa〈/em〉 (common causes of orthopedic device-associated infections). Bacterial colonization was examined in terms of the initial bacterial concentration, as well as bacterial adherence to and growth on the surface and inside the pores. Results suggest that fully dense titanium supported the least bacterial colonization, while the porous titanium promoted bacterial growth in the medium and inside the cavities. Furthermore, the SPEEK coating deposited onto the samples inhibited bacteria growth inside the porous materials. In this manner, this study showed for the first time that SPEEK could have potential antibacterial properties to offset the increase in bacteria growth commonly observed in porous materials.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897218312052-ga1.jpg" width="440" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Xiaolong Cai, Lisheng Zhong, Yunhua Xu, Xin Li, Mingxin Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To improve the mechanical properties of the surface of iron-based alloys, a tungsten carbide-iron (WC-Fe) cemented carbide layer is produced on an alloy by adopting an isothermal annealing process, which was performed at 1050 °C for 4 h. By deeply etching the obtained sample, the morphologies of the WC ceramic grains in the WC-Fe hardmetal layer are characterized via scanning electron microscopy. The present results reveal three distinct morphologies consisting of rectangular, triangular prism and multi-layered shapes. Furthermore, the mechanical properties and fracture toughness of the WC-Fe layer are investigated through combined nanoindentation and Vickers indentation techniques. Nanoindentation testing is performed in a load range of 100 to 450 mN. Based on the data collected from the nanoindentation results, the average values of the hardness, Young' modulus and deformation ratio are evaluated, and the fracture toughness is determined to have a value of 3.08 MPa·m〈sup〉½〈/sup〉 at 450 mN. In the Vickers indentation technique, however, by identifying the crack type and choosing the appropriate model, the fracture toughness is calculated to be 1.85–3.44 MPa·m〈sup〉½〈/sup〉 at applied loads ranging from 0.98 to 4.9 N. The obtained fracture toughness results exhibit good consistence between the nanoindentation and Vickers indentation methods.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Y. Le Guével, B. Grégoire, M.J. Cristóbal, X. Feaugas, A. Oudriss, F. Pedraza〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrolytic dissolution of aluminide coatings on model (pure Ni, Ni20Cr) and René 125 Ni-based superalloy was conducted by alternated cathodic and anodic polarizations. The pure nickel aluminide dissolved homogeneously. In contrast, the inhomogeneity of dissolution increased with the incorporation of Cr in the coating. The coatings were however uniformly dissolved when the cathodic step was eliminated. XPS and TEM demonstrate that the occurrence of a passive layer containing Cr and Al oxy-hydroxides blocked dissolution.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉(a) TEM bright field images of the passive film of the aluminized Ni20Cr. (b) is a greater magnification showing the distance between the crystalline planes. (c), (d) and (e) are the selected area diffraction patterns of the three diffracted areas defined on (a). The distances marked in red correspond to “d”, i.e. the interplanar distance.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897218311976-ga1.jpg" width="343" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Lijia Fang, Jing Huang, Yi Liu, Botao Zhang, Hua Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The booming ocean economy in recent decades crucially demands advanced anti-corrosion technologies for marine infrastructures. Among the marine protective coatings developed in past decades, thermal sprayed aluminium coating was evidenced to be one of the most economical and efficient corrosion protection layers. Yet, marine corrosion is always accompanied by biofouling which in most cases accelerates corrosion. Here we report arc spray fabrication of novel aluminium-copper coatings using home-made Al-Cu cored wires for both anti-corrosion and antifouling performances. Copper particles were dispersed in the as-sprayed coatings, and TEM characterization further revealed partial interaction of Cu particles with Al matrix during the coating deposition. The chemical reaction with the formation of Al〈sub〉2〈/sub〉Cu offered an anchoring effect for the coatings preventing Cu particles from quick releasing into aqueous environment. Electrochemical testing in artificial seawater showed that the presence of Cu in Al coatings did not trigger considerable deterioration in corrosion resistance. Further antifouling testing of the coatings by examining settlement and colonization behaviors of bacteria 〈em〉E. coli〈/em〉 and 〈em〉Bacillus〈/em〉 sp. and typical marine algae revealed their excellent antifouling performances. The antifouling properties were predominately attributed to the continuous release of copper ions from the coatings. The results give clear insight into constructing anti-corrosion/fouling inorganic coatings by the cored-wire arc spray technical route for marine applications.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Jinjiao Xia, Wenping Liang, Qiang Miao, Diederik Depla〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Yttrium oxide thin films are grown by reactive magnetron sputtering. To achieve a high deposition rate, target poisoning is avoided by local oxygen addition at the substrate. In all deposited thin films only the monoclinic Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 phase is observed. A strong variation in the film texture across the sample for experiments with a stationary sample stage is noticed. This inhomogeneity can be partially traced back to an uneven oxygen gas distribution. Sample rotation resolves this problem, but still the gas distribution influences both the texture and the Bragg peak positions. Several configurations for the gas supply are tested with a different number of gas distribution pipes. An overview of all experiments shows an interesting correlation between the texture coefficient and the peak position of the monoclinic (111) Bragg reflection. When the peak shifts towards higher diffraction angles, the texture coefficient drops as a higher contribution of the 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.gif" overflow="scroll"〉〈mfenced close=")" open="("〉〈mrow〉〈mn mathvariant="normal"〉40〈/mn〉〈mover accent="false"〉〈mrow〉〈mn mathvariant="normal"〉2〈/mn〉〈/mrow〉〈mo mathvariant="normal"〉¯〈/mo〉〈/mover〉〈/mrow〉〈/mfenced〉〈/math〉 orientation is observed. This trend however is further complicated by the exact geometrical configuration on the deposition rate, and the energy/momentum of the species arriving at the substrate. As previously reported, an increasing energy/momentum per deposited atom results in monoclinic thin films with a preferential (111) out-of-plane orientation.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 358〈/p〉 〈p〉Author(s): R. Jamshidi, O. Bayat, A. Heidarpour〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Pure Al coatings are extensively used in various industries but their poor wear resistance has introduced as the main drawback of them. In this study, the effect of the addition of Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 on the tribological and corrosion behavior of Al coating was investigated. The morphological and phase evolution of coating and powders was analyzed using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) patterns. The corrosion behavior of samples was investigated by potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS). The wear behavior of coating and substrate studied by the pin-on-disc test. The results indicated that the wear resistance of Al coating in terms of friction coefficient and wear rate was significantly improved by the presence of Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 inclusions. According to the result of potentiodynamic polarization tests in simulated 3.5% NaCl solution, the corrosion potential of the Al/Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 coating is nobler than that of the pure Al one. The electrochemical impedance spectroscopy (EIS) tests indicated that corrosion resistance of Al/Ti〈sub〉3〈/sub〉SiC〈sub〉2〈/sub〉 coating was increased as compared with pure Al coating.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Małgorzata Norek, Łukasz Szamyjer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A multi-variant process of cold rolling to different reductions of thickness (0–50%) and subsequent heating under different temperature was applied to Al substrates. Next, a comprehensive analysis of the influence of various microstructural, structural, and mechanical parameters of the Al substrates on the nanopore growth in anodic aluminum oxide (AAO), was performed. As an effect, new evidences concerning an important role of Al substrate state on the AAO growth were provided. The obtained results unambiguously show that the number of dislocations is the only parameter responsible for the regular pore formation is the AAO. Since the dislocation density is greatly reduced solely after recrystallization process, a significant reduction of the percentage of defects in AAO occurs only when Al substrate is annealed at the recrystallization temperature (483 °C), independent of percent cold work. All microstructural (elongation, circularity, and size of grains) or structural (texture, lattice strain) parameters are irrelevant for the pore formation, until the number of dislocations in the Al substrate remains high. Therefore, before anodization Al substrate should be annealed, at least for 1 h, under the temperature ≥ recrystallization temperature, not lower. Stress-relief anneal at temperature 〈 recrystallization temperature is not sufficient to induce a regular pore growth in AAO.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 358〈/p〉 〈p〉Author(s): Yanming He, Chuanyang Lu, Wenjian Zheng, Jianguo Yang, Shuangjian Chen, Zhijun Li, Yuan Sun, Zengliang Gao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, a composite coating prepared by laser cladding on a Ni-17Mo-7Cr based superalloy was thermally exposed at 1073 K for 240 h. A detailed electron microscopy examination was performed to characterize the microstructure of the aged coating. Results indicate that: the original Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C dendrites in the aged coating were coarsened while the coarsening layers were essentially the Mo-deficient and Cr-rich Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C, due to low diffusivity of Mo. Long-term thermal exposure promoted a great amount of nano-sized Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C and micro-sized Cr〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 particles being precipitated in the interdendritic zones. In the aged coating, three types of Cr〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 were presented: discrete Cr〈sub〉3〈/sub〉C〈sub〉2〈/sub〉, Cr〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 close to the graphite and Cr〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 approaching to the Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C. The transformation of Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C to Cr〈sub〉3〈/sub〉C〈sub〉2〈/sub〉 merely occurred in the newly formed Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C rather than in the original Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C dendrites, because deficiency of Mo and enrichment of Cr in the new Mo〈sub〉6〈/sub〉Ni〈sub〉6〈/sub〉C depressed their stability. Lastly, the mechanical behavior of the aged coating was characterized by Vickers hardness, nano-indentation and nano-scratch tests with the aim to unveil the effect of microstructural evolution on mechanical properties. Our findings provide basic information to understand the aged-induced microstructural modification and its effect on mechanical properties for a laser-induced coating prepared on the Ni-17Mo-7Cr based superalloy. The results obtained cannot only apply to the investigated Ni-based superalloys, but also to other Hastelloy series superalloys.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Anke Dalke, Igor Burlacov, Stephan Hamann, Alexander Puth, Jan Böcker, Heinz-Joachim Spies, Jürgen Röpcke, Horst Biermann〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Plasma nitrocarburizing based on active screen technology using a carbon-fiber reinforced carbon active screen was applied in an industrial-scale unit for thermochemical surface treatment of austenitic stainless steel. This concept is based on the use of a solid-carbon-source for the generation of highly reactive process gases directly in the active screen plasma. In this work, plasma nitrocarburizing of AISI 316L stainless steel was performed by means of the variation of the precursor gases H〈sub〉2〈/sub〉 and N〈sub〉2〈/sub〉 in the range of 0% N〈sub〉2〈/sub〉 up to 100% N〈sub〉2〈/sub〉 without the use of any additional carbon bearing gas. For a set of H〈sub〉2〈/sub〉-N〈sub〉2〈/sub〉 gas mixtures, the resulting reaction gas was monitored using infrared laser absorption spectroscopy (IRLAS). The four main stable species HCN, CH〈sub〉4〈/sub〉, NH〈sub〉3〈/sub〉 and C〈sub〉2〈/sub〉H〈sub〉2〈/sub〉 were detected. A detailed analysis of the surface microstructure resulting for each specific H〈sub〉2〈/sub〉-N〈sub〉2〈/sub〉 precursor gas mixture was performed. This included glow discharge optical emission spectroscopy (GDOES), optical microscopy, micro hardness measurements, as well as X-ray diffraction analysis.〈/p〉 〈p〉The concentrations of hydrocarbons CH〈sub〉4〈/sub〉 and C〈sub〉2〈/sub〉H〈sub〉2〈/sub〉 were most abundant in case of pure hydrogen plasma, and a carbon-expanded austenite layer with hardness values up to 600 HK0.01 and smooth hardness gradient resulted. The admixture of N〈sub〉2〈/sub〉 to the precursor gas significantly increased the concentrations of HCN and NH〈sub〉3〈/sub〉. Due to this, a duplex structure of nitrogen-expanded austenite γ〈sub〉N〈/sub〉 and carbon-expanded austenite γ〈sub〉C〈/sub〉 formed. With increasing content of N〈sub〉2〈/sub〉 up to 50% in the precursor gas, the resulting layer thickness increased and the hardness reached values up to 1300 HK0.01. At strong nitrogen excess in the precursor gas, the nitrogen concentration in the expanded austenite significantly increased, the Fe〈sub〉2–3〈/sub〉(N, C) phase was formed, and simultaneously the layer thickness decreased. Structure and properties of the expanded austenite layer significantly changed by only varying the H〈sub〉2〈/sub〉-N〈sub〉2〈/sub〉 ratio of the precursor gas mixture.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 357〈/p〉 〈p〉Author(s): Sima A. Alidokht, Stephen Yue, Richard R. Chromik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cold spray is a relatively new method used to deposit WC reinforced composite coatings, where its low temperature is advantageous for avoiding oxidation and carbide decomposition. Previous studies demonstrated that using powders made from agglomerated WC resulted in higher WC retention in a sprayed coating when compared to that of cast WC. However, the influence of the morphology of the starting powders on the coating's microstructure, properties, and wear performance is not well understood. Here, we report cold spray deposition of Ni with two types of WC particles, i.e. cast and agglomerated. In both cases, ~30 vol% WC was retained in coatings, allowing for a side-by-side comparison. Coatings with cast WC featured a multi-modal distribution of WC particles ranging from 0.2 to 20 μm with a mean free path (MFP) between particles of 8.5 ± 0.7 μm. In comparison, coatings with agglomerated WC had WC size range of 0.3 to 1.3 μm and an MFP of 31 ± 4 μm. The sliding wear behavior of coatings was studied with a sliding speed of 3 mm/s under normal loads of 5 and 12 N. Coatings with cast WC were found to be more wear resistant than coatings with agglomerated WC. The multi-modal size distribution of cast WC with significantly lower MFP minimized adhesive wear and helped to develop a higher coverage of protective mechanically mixed layers (MMLs) that typically formed near WC particles. For coatings with cast WC, subsurface microstructure and chemical analysis suggested higher oxidation for MMLs with shallower depths of deformation in the metal matrix beneath the MMLs compared to coatings with agglomerated powder. The main factors for improved wear resistance of cast WC coatings compared to agglomerated WC coatings were the stability of the MMLs, and the wider size distribution with lower MFP, which offered better load supporting properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 30 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): Yongxiong Chen, Junchao Shang, Xiubing Liang, Haoxu Wang, Zhidan Zhou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to improve the coating quality to a higher level, a method of warm-particle peening assisted thermal spraying was put forward. This work presents a study based on a warm-particle peening assisted high-velocity oxy-fuel (WPPA-HVOF) spray system, in which the spraying powder was injected from the port near the gun nozzle throat and the peening media was injected from the port outside the gun barrel exit. A type of FeBSiNb amorphous coating was prepared by the WPPA-HVOF process and compared with that of the traditional HVOF process. The in-flight particle velocity and temperature were tested using a high-speed thermal spray process monitoring system, which manifests that the velocity and temperature of the awaiting deposit powder are hardly affected by the addition of peening particles. Through characterization of the deposit by methods such as SEM, EDS, and FIB, it was found that the peening particle is rebounded after impacting on the substrate. As a result, there were no peening particles mingled in the deposited coating even when the feed rate was as high as 140 g/min. A by-product is that the coating structure becomes dense, e.g. the porosity can be as low as 0.7%. The WPPA-HVOF process results in a decrease in coating surface residual stress to compressive state. The properties such as microhardness, cohesive strength and wear resistance increase to varying degrees consequently. It is hypothesized that this is attributed to the large compressive residual stress because of warm-particle peening during the deposition process.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219303548-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 30 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): Z.R. He, C.S. Liu, X.H. Jie, W.Q. Lian, S.T. Luo〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Crystallization fouling adhered on the heat transfer surface is a serious problem. Here, we report an anti-fouling heat transfer surface prepared by magnetron sputtering (MS) a-C film on an electrical discharge machining (EDM) Cu surface (MES). Microstructure, chemical composition, wettability and anti-fouling property of the resulting modified surface were analyzed by SEM, EDS, XRD, XPS, Raman, Contact angle measurement, Atomic Absorption Spectroscopy and homemade heat transfer performance testing device. The formation of CaCO〈sub〉3〈/sub〉 fouling and the anti-fouling mechanism of the as-prepared surface are also discussed. The results show that the surface prepared by EDM and MS displays a micro/nano structure with a-C film deposited on it. The combination of micro/nano structure and the low surface energy a-C film endows the MES with higher contact angles for both water and glycerol as well as superior anti-fouling property than the polished Cu surface (PS) and the EDM Cu surface (ES). This work offer an effective strategy and promising application for fabricating anti-fouling heat transfer surface.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 29 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): T.R. Praveen, H. Shivananda Nayaka, S. Swaroop〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉AM80 magnesium alloy was processed with Equal Channel Angular Press (ECAP) for grain refinement. Laser shock peening without coating (LSPwC) were executed on ECAP processed sample at 8 GW cm〈sup〉−2〈/sup〉 and further grain refinement were observed at surface. SEM image expose the grain refinement at different stage of processing, and fine grains of sub-micron size were observed at surface level after ECAP + LSPwC. Residual stress were measured using X-ray diffraction, sin〈sup〉2〈/sup〉(〈em〉Ψ〈/em〉) method and compressive residual stress was found after ECAP. LSPwC intensify the compressive residual stress at surface. Increases in magnitude of residual stresses were noticed with 200 and 300% of LSPwC. Increase in surface roughness were noticed from 0.6 to 6.8 μm by increasing the percentage of LSPwC coverage. Fatigue tests were acknowledged the effect of ECAP and ECAP + LSPwC on reliability of grain refinement technique. ECAP sample showed fatigue life of 7539 cycles against as received. Highest fatigue life of 85,268 life cycles was observed with ECAP + LSPwC by 100% of coverage. Further process of LSPwC for 200 and 300%, fatigue life was significantly decreases to 22,987 and 384 cycles respectively. SEM images of fractured surface exhibits effect of ECAP and LSPwC on crack initiation and propagation for failure.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): Shan Yang, Binglin Zou, Jiagen Shen, Xiaolong Cai, Ying Wang, Xueqiang Cao, Ling Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Thermal barrier coatings (TBCs) consisting of yttria-stabilized zirconia (YSZ) as top coat and NiCrAlY as bond coat were deposited on AZ91D magnesium alloy substrate by atmospheric plasma spraying (APS). In order to improve the stability and prolong the thermal shock life of TBCs, a Ni-P/Al/Ni-P sandwich interlayer between the AZ91D magnesium alloy substrate and the NiCrAlY bond coat was fabricated by electroless plating for Ni-P layer and APS for Al layer. The thermal shock behavior of the YSZ TBCs with the Ni-P/Al/Ni-P sandwich interlayer quenched in water at 400 °C was investigated in detail. The results showed that the thermal shock life of YSZ TBCs with the Ni-P/Al/Ni-P interlayer on the AZ91D substrate was about 226 cycles. The failure of YSZ TBCs in thermal shock test was mainly induced by the corrosion of AZ91D substrate. The results of polarization tests and electrochemical impedance spectroscopy showed that the Ni-P/Al/Ni-P interlayer had better corrosion protection for the magnesium alloy substrate than the Ni-P interlayer, which thus enhanced the thermal shock life nearly two times as compared to that of YSZ TBCs with the Ni-P interlayer.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): R. Nikbakht, S.H. Seyedein, S. Kheirandish, H. Assadi, B. Jodoin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cold spraying of dissimilar materials have been addressed to understand the role of deposition sequence on the characteristics of the coating/substrate interface. Nickel and titanium coatings were sprayed onto the substrates of the opposite material under different conditions. The samples were subsequently heat treated, to better reveal the quality of metallic bonding at different locations, and examined by mechanical testing and microstructural analysis. The results show that the bonding characteristics of the Ni(coating)/Ti(substrate) pairs are significantly different from those of the Ti(coating)/Ni(substrate) pairs. Mechanical interlocking and intermixing instabilities were observed only at the interfaces of the Ni/Ti pairs, which also showed a more uniform and higher fraction of intermetallics compared to the Ti/Ni pairs in similar spraying conditions. This was attributed to higher degrees of particle/substrate deformation in the Ni/Ti pair. Also, the bond strength of the Ni/Ti pair appeared to be almost three folds of the Ti/Ni pair (64.31 MPa vs. 22.8 MPa). These findings are considered to have implications in cold-spray additive manufacturing of hybrid components or bimetals.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219303421-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): Yue Teng, Yuan-Yuan Guo, Min Zhang, Yong-Jie Yang, Zhen Huang, Yan-Wen Zhou, Fa-Yu Wu, Ying-Shuang Liang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, two types of transition layers (pure Cr and gradient CrN〈sub〉x〈/sub〉) were fabricated between plasma-assisted nitrided (PAN) stainless steel and magnetron sputtering CrN coating to investigate the effect of transition layer on mechanical properties of CrN coating on PAN stainless steel substrates. For comparison, samples without transition layer were also synthesized. The phase structure, morphology, abrasive resistance and adhesion of the CrN coatings, as well as the nano-hardness and Young's modulus were investigated by XRD, SEM, ball-on-disk tribometer, scratch tester and nano-indentation tester, respectively. The results showed the transition layers of pure Cr and gradient CrN〈sub〉x〈/sub〉 absorbed the excess nitrogen diffusing outwards from the nitrided layer, and thus suppressed partially the precipitation. As a result, the adhesion force was improved to 25.7 N, respectively. The nano-hardness and Young's modulus of modified layers were improved to the range of 22.8–25.8 GPa and 331–347.3 GPa, corresponding to the substrate of 7.2 GPa and 230.5 GPa. The modified layer with no transition layer had the best wear resistance for nitriding of 1 h; while the layer with gradient CrN〈sub〉x〈/sub〉 had the best wear resistance for nitriding of 4 h.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): 〈/p〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Stephan Mändl, Darina Manova〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉While plasma immersion ion implantation (PIII) has shown a remarkable success story in its development, recently it appears to be stagnating. This review tries to shed some light on the dichotomy between the industrial success of plasma doping and the superficial dearth of industrial applications for functional coatings or biomedical implants. It is surmised that the use of high voltage pulses between 5 and 25 kV leads to excessive heat deposition, reducing the effective deposition rate, and large gradients in sputtering across the substrate surface, which is more detrimental than those in comparable recent methods, e.g. high power impulse magnetron sputtering (HiPIMS).〈/p〉 〈p〉However, the peculiarities of PIII can still be used rewardingly when focusing more on model experiments to understand specific fundamentals of ion surface interactions. The first example concentrates on dynamic measurements of secondary electron emission coefficients measured while the surface is actually changing. Another example shows how a combination of dedicated experiments can help to elucidate information on the formation of expanded austenite formed by nitrogen insertion into austenitic stainless steel. Nevertheless, for that case there are still open questions requiring further work.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Darina Manova, Stephan Mändl〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Plasma immersion ion implantation (PIII) is characterized by applying short high voltage pulses to a substrate immersed in a low pressure plasma discharge. Compared to a more conventional experimental setup for glow discharge optical emission spectroscopy (GDOES) where sputtered atoms are detected, the PIII experiment is characterized by higher ion energies of the primary ions, lower pressures with a larger mean free path, shorter pulses and a higher relative energy density deposited by the secondary electrons emitted from the surface. Using time resolved optical emission spectroscopy (OES) during PIII high voltage pulses, detailed insights into the interactions of sputtered atoms, secondary electrons and the low pressure plasma discharge are possible. Thus, a direct excitation of the sputtered particles by the secondary electrons is highly unlikely due to the small cross-sections. However, a transient increased optical emission was observed with the maximum intensity about 20–80 μs after the end of the high voltage pulse. This delayed excitation of Ar I, Ar II and Me I lines scale with the secondary electron emission coefficient. Nevertheless, transient plasma excitations including long-living metastable states by secondary electrons could be probed in this setup.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): X.D. He, L. Dong, J. Wu, D.J. Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉TiB〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 multilayers with constant modulation periods and various modulation ratios ranging from 1:1 to 11:1 were synthesized on silicon wafer substrates by magnetron sputtering system. The amorphous structures of the TiB〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 multilayers were characterized. The effect of modulation ratio on the microstructure and mechanical properties of the multilayers was investigated. The results revealed that crystallization of amorphous sublayer, performance of hardness, elastic modulus and residual stress of the multilayers largely depended on variations of modulation ratios. The hardness and elastic modulus of TiB〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 multilayers were up to the maximum value (30.6 GPa and 460.1 GPa) at modulation ratio of 7:1. Moreover, the practical adhesion had been also remarkably improved. Further analysis suggested that crystallization of amorphous sublayer (individual layer) was the primary cause for mechanical performance improvement of the multilayers. This work proved that the modulation ratio was a key role in controlling the growth orientation of crystals of nanoscale TiB〈sub〉2〈/sub〉/Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 multilayers at room temperature.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Gang Gao, Lei Yang, Bing Dai, Fei Xia, Zhenhuai Yang, Shuai Guo, Peng Wang, Fangjuan Geng, Jiecai Han, Jiaqi Zhu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉As lanthanum oxide (La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) has a large bandgap, it exhibits excellent optical properties. In this work, La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 thin films are prepared by the sol-gel method from a lanthanum chloride (LaCl〈sub〉3〈/sub〉) precursor, on quartz and sapphire (0001) substrates. The effect of the annealing temperature (400–800 °C) on the optical properties of the La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 films is investigated. The structure and optical properties are analyzed by X-ray diffraction, atomic force microscopy, scanning electronic microscopy, X-ray photoemission spectroscopy, Raman spectroscopy, ultraviolet (UV)–visible spectroscopy, Fourier transform infrared spectroscopy, and infrared variable angle spectroscopic ellipsometry. Results indicate that with an annealing temperature of ~600 °C, the roughness and optical properties of La〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 films can be significantly improved.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Qi Xie, Zhiqiang Fu, Xian Wei, Xiaoyao Li, Wen Yue, Jiajie Kang, Lina Zhu, Chengbiao Wang, Jianping Meng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to further improve the mechanical properties of CrN films, the influence of substrate bias current on the microstructure and properties of the CrN〈sub〉x〈/sub〉 films deposited by plasma enhanced magnetron sputtering was studied by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, 3D profiler, nano indenter, and ball-on-disk tribometer. With the increase of substrate bias current, the microstructure of the films is transformed from a dendritic structure into a super dense columnar structure, and the phase composition is evolved from Cr → Cr + Cr〈sub〉2〈/sub〉N → pure Cr〈sub〉2〈/sub〉N. When the substrate bias current is 〉1.5 A, the preferred orientation is transformed from Cr〈sub〉2〈/sub〉N(111) to Cr〈sub〉2〈/sub〉N(300) with increasing substrate bias current. The surface roughness of the films is decreased from 27.3 to 18.7 nm as the substrate bias current is increased from 0.1 to 1.5 A, but the surface roughness remains nearly unchanged when the substrate bias current exceeds 1.5 A. The hardness and effective Young's modulus of the films are obviously increased with increasing the substrate bias current from 0.1 to 3.0 A, while they are almost independent of the substrate bias current when the substrate bias current is no less than 3.0 A. The lowest friction coefficient of 0.43 is obtained when the substrate bias current is 4.5 A. When the substrate bias current is increased, the wear rate of CrN-coated samples is first increased and then decreased, and the lowest wear rates is 4.6 × 10〈sup〉−16〈/sup〉 m〈sup〉3〈/sup〉/(N·m) when the substrate bias current is 6.0 A.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Cuiqing Jiang, Zhongzhen Wu, Shu Xiao, Zhengyong Ma, Liangliang Liu, Ricky K.Y. Fu, Paul K. Chu, Hai Lin, Feng Pan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Nb-doped TiO〈sub〉2〈/sub〉 (NTO) films have potential to replace indium tin oxide (ITO) as transparent conducting material. However, costly substrates with a specific orientation such as sapphire must be used to avoid formation of the rutile phase and to obtain transparent and conductive NTO films. Furthermore, scaling up is difficult thus hampering commercialization. Herein, in order to control the crystal orientation of TiO〈sub〉2〈/sub〉, two-step preparation is described. An amorphous NTO film is first prepared on the economical soda-lime glass substrate by low-energy magnetron sputtering and the sample is annealed in Ar with 5 at% H〈sub〉2〈/sub〉 at 400 °C to crystallize the amorphous structure into anatase (101) and anatase (004). The morphology, structure, and optoelectrical properties of the NTO films and relationship with film thickness are studied. The resistivity decreases to 8.1 × 10〈sup〉−4〈/sup〉 Ω·cm for a thickness of 320 nm and the average transmittance in the visible region increases monotonically to 73% as the thickness is reduced from 400 nm to 280 nm. The good conductivity and transmittance suggest potential application to smart windows and solar cells.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): L. Wang, C. Ming, X.H. Zhong, J.X. Ni, S.Y. Tao, F.F. Zhou, Y. Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the current work, the yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs) have been fabricated by atmospheric plasma spraying. The failure mechanism of the TBCs during burner rig test (BRT) has been investigated via finite element modeling (FEM) and in-situ acoustic emission (AE) technique systematically. During the BRT, the oxygen-propane flame was heated onto the surface of the coating samples with the dwell time 3 min, then the surface and the backside of the coating samples were cooled by the compressed air simultaneously for 3 min. This can be viewed as one thermal cycle. Then repeat the same heating and cooling process. The history and distribution of the temperature along the through-thickness direction of the coating samples has been obtained via FEM, and the residual stress at different stages has been also calculated. The FEM results have indicated that large tensile stress and compressive stress existed at the heating stage and cooling stage of each thermal cycle, respectively. The crack propagation tends to occur at the initial period of heating stage in the BRT process. The in-situ acquisition of the AE signals during the BRT has also been adopted. The crack propagation patterns have been obtained based on the analysis of AE signals. The filtering technique has been used to exclude the disturbance of the noise in the process of BRT in order to capture the actual and effective AE signals which represent the crack propagation and the deformation of the coating systems. Based on the characteristic waveform of effective AE signals, the Fast Fourier Transformation (FFT) and wavelet transformation has been adopted to analyze the key distribution range of the amplitude and frequency. The investigation results indicate that the acquired AE signals during BRT mainly include signals which came from the plastic deformation of the substrate and creep of each layers, propagation of the vertical crack and propagation of the interfacial cracks (horizontal crack). The detailed failure mechanisms of the TBCs during BRT have been clarified in the current work.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 25 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 366〈/p〉 〈p〉Author(s): A.H. Pakseresht, M. Saremi, H. Omidvar, M. Alizadeh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The present study describes the experimental results regarding the effect of the addition of ceramic whisker, on the microstructural and friction property of plasma sprayed yttria-stabilized zirconia coating sprayed on an Inconel substrate with optimized process parameters. To deposit a bond layer between the ceramic top coat and substrate surface, all samples have coated with the metallic intermediate NiCrAlY bond coat. For the microstructural study, the powders/coatings morphology and wear marks on YSZ coated were investigated by a Field Emission Scanning Electron Microscopy and Energy Dispersive X-ray analysis (FE-SEM/EDS). The mass loss, wear resistance and coefficient of friction of the YSZ top coat against Alumina Ball were tested with a ball-on-disc wear testing at loads of 7,10 and 13 N. The results showed that reinforced coating gives a higher wear resistance compared to the conventional coating without changing the friction coefficient. The improvement in wear resistance of the ceramic whisker reinforced coatings could be mainly due to the interlocking interface between splats and decrease of intralamellar cracks in the top coat. The wear mechanisms of reinforced and unreinforced TBC were discussed in terms of exfoliation and degradation wear mechanisms.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Hao Li, Chuan Zhang, Chan Liu, Meidong Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of nickel ion implantation on surface structure as well as resistance against corrosion for CrN coatings deposited by arc ion plating are investigated. The objective of this work is to optimize the deposition condition for the best corrosion resistance. In this experiment, nickel ions with energy of 20 keV were implanted into CrN coatings by doses from 1 × 10〈sup〉17〈/sup〉 to 1 × 10〈sup〉18〈/sup〉 ions/cm〈sup〉2〈/sup〉. X-ray diffraction analysis was applied for both the metallic analysis and the study of new structures created during the implantation. Atomic force microscopy and corrosion analysis were utilized to compare the roughness and the corrosion resistance prior to and after the implantation, respectively. The results indicate that nickel ion implantation can greatly improve the resistance against corrosion. After the corrosion test, the surface morphology and composition of the coatings were examined by the scanning electron microscopy with an energy dispersive spectroscopy, which confirmed the existence of the implanted nickel in the coatings.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): A. Shelemin, D. Nikitin, P. Pleskunov, M. Vaidulych, R. Tafiichuk, A. Choukourov, P. Kúš, P. Solař, A. Kuzminova, O. Kylián, H. Biederman〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel technique that enables the production of a-C:H coatings decorated either by sub-micron concave or convex structures is presented. The technique is based on several steps that involve i) pre-seeding of substrates with C:H sub-micron particles produced by a gas aggregation cluster source, ii) overcoating of the C:H particles by thin a-C:H coatings produced by plasma enhanced chemical vapor deposition and iii) optional ultrasonic lift-off of the C:H particles. The main focus is set on the characterization of the morphology of the resultant structures as well as on the comparison of their wettability. It is shown that the properties of the structured a-C:H coatings may be precisely controlled by the number of the C:H particles. Different dynamic wetting of convex and concave structures is reported, although static wettability is the same. For concave wells (maximum depth 90 nm) the dynamics of water droplet drying is similar to the one observed on smooth a-C:H films and is characterized by three well-distinguishable phases – the constant contact radius phase, the constant contact angle phase and the mixed phase – independently of the number of wells. By contrast, the increasing number of convex bumps (300 nm in height) gradually impedes the movement of a triple line which progressively suppresses the constant contact angle phase. Subsequently, the differences in the droplet drying have a strong impact on the bovine serum albumin patterns formed after the complete evaporation of droplets. Spatially irregular protein pattern is observed on smooth and well-decorated concave a-C:H coatings while a well-defined “coffee-ring” structure is formed on the a-C:H coatings decorated with convex structures.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219303378-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Abdul Mateen Qasim, Farhat Ali, Hao Wu, Ricky K.Y. Fu, Shu Xiao, Yunpo Li, Zhongzhen Wu, Paul K. Chu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Titanium nitride films deposited by conventional magnetron sputtering are prone to contamination, especially residual gas species, and the composition and properties can be affected. In this work, an anode layer ion source (ALIS) is used in magnetron sputtering to deposit TiN films and the effects of the average energy 〈em〉E〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉 and ion flux density 〈em〉J〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉 on the chemical composition of the deposited films are determined. By coupling and varying the magnetron discharge current 〈em〉I〈/em〉〈sub〉〈em〉t〈/em〉〈/sub〉, the ALIS can be used to control 〈em〉E〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉 to as low as 80 eV and 〈em〉J〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉 as high as 3.5 × 10〈sup〉16〈/sup〉 ions cm〈sup〉−2〈/sup〉 s〈sup〉−1〈/sup〉. To discern the roles of 〈em〉E〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉 and 〈em〉J〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉, the films are deposited under three different conditions of magnetron discharge 〈em〉I〈/em〉〈sub〉〈em〉t〈/em〉〈/sub〉. A reduction of 95% in the oxygen concentration and an increase of 30% in the nitrogen concentration are observed by increasing 〈em〉J〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉. X-ray photoelectron spectroscopy reveals decreased peak broadening, shifts to higher binding energies, and increase initial slope of the Ti 2p peak with larger 〈em〉J〈/em〉〈sub〉〈em〉i〈/em〉〈/sub〉. The N 1s peak shows decreased broadening while the O 1s peak indicates less oxide-related compounds. Raman scattering reveals reduced intensity ratios of the Ti to N vibration phonon peaks (〈em〉I〈/em〉〈sub〉〈em〉Ti〈/em〉〈/sub〉〈em〉/I〈/em〉〈sub〉〈em〉N〈/em〉〈/sub〉) indicating enhanced nitrogen-related optical phonon peaks and that the film resistivity decreases as the oxygen concentration decreases. Our experiments disclose compositional changes especially reduced oxygen incorporation with ALIS assistance during magnetron sputtering. The hybrid technique which can be scaled up readily to meet industrial demand enables control of the film composition without resorting to other parameters like high temperature, biasing, and ultrahigh vacuum that may adversely affect other film properties and add manufacturing costs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Yuyao Nie, Lei Dong, Jie Wu, Dejun Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A series of TC4/ZrB〈sub〉2〈/sub〉 nanomultilayers with different modulation periods (〈em〉Λ〈/em〉) were fabricated on the Si substrate by the magnetron sputtering technique. The results indicated that all the multilayers showed a lower crystallization at the lower 〈em〉Λ〈/em〉 values ranging from 15 to 40 nm and presented the structure of mixed layer/amorphous layer/crystallization layer. Owing to the enhancement of crystallinity of ZrB〈sub〉2〈/sub〉 that prevented grain-boundary sliding, the highest hardness (24.81 GPa) and elastic modulus (283.70 GPa) values were realized at 〈em〉Λ〈/em〉 of 40 nm. The lowest surface roughness (〈em〉R〈/em〉〈sub〉a〈/sub〉 = 0.332 nm) were obtained at 〈em〉Λ〈/em〉 of 20 nm. The smaller grain size at the lower 〈em〉Λ〈/em〉 should be one of the main contributions to the improved mechanical properties. As the crystal layers were covered by mixed layers and amorphous layers, the multilayers also exhibited excellent thermal stability. High temperature annealing experiments showed that the multilayers maintain good microstructure and the hardness slightly increased after annealed at 600 °C. Therefore, the existence of the amorphous layer is favorable for buffering high temperature damage to the interface of the multilayers, resulting in an increase in the high temperature stability of the multilayers.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 26 March 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): Yibo Ouyang, Jin Zhao, Ri Qiu, Shugang Hu, Ming Chen, Peng Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ti finds widespread opportunities in harsh seawater environment because of unique corrosion resistance. However, one tough challenge is the biofouling problem caused by the inherent friendliness to the attachment of biological organisms. In this study, a facile electrodeposition approach affords high driving force for crystal growth, and dendritic Ag has been constructed onto Ti substrate. After being modified with dodecanethiol vapor, superhydrophobicity is realized relying on the anchored hydrophobic moieties and the voids in dendritic Ag matrix. Superoleophilicity enables oil phase to drive out air in the matrix for finally achieving slippery liquid-infused porous surface (SLIPS) with high flatness and smoothness. Diatoms and green algae are used as the typical biofouling organisms to assay antifouling behavior of Ti covered by superhydrophobic (SHP Ti) and SLIPS surface (SLIPS Ti). After immersion for 14 days, the number of diatoms and green algae on bare Ti surface respectively reaches 1.60 × 10〈sup〉11〈/sup〉 and 1.57 × 10〈sup〉11〈/sup〉 cells/cm〈sup〉2〈/sup〉. Meanwhile, for Ti covered by SLIPS, the cell density is only 6.84 × 10〈sup〉7〈/sup〉 cells/cm〈sup〉2〈/sup〉 and 5.05 × 10〈sup〉7〈/sup〉 cells/cm〈sup〉2〈/sup〉, decreasing to ca. 4 orders of magnitude smaller than that of bare Ti. For SHP Ti, its biofouling inhibition effect is lower than that of SLIPS Ti. Therefore, building SLIPS onto the surface has afforded a promising way for Ti to inhibit biofouling in seawater environment.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉Bio-inspired liquid-infused surface based on dendritic Ag matrix from electrodeposition affords prominent biofouling inhibition to underneath Ti in seawater environment.〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0257897219303445-ga1.jpg" width="382" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Zhao-Yi Tan, Yong-Gang Yuan, Huan An, Yu Zou, Jian-Chun Wu, Chang-Yong Zhan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To find a sacrificed layer on walls of silicon macropore, the microporous silicon (MPS) was formed on the wall of straight silicon macropore (SSMP) by electrochemical etching on n-type silicon. The front side illumination was used to control the thickness of MPS on SSMP wall. The experiment showed that the thickness of MPS was more easily controlled by changing the illumination than the applied electric field and etching electrolyte. So the injected carrier model (ICM) was proposed for deducing an experimental equation between the illuminance and MPS thickness. Light attenuation in silicon was confirmed as the major cause of MPS formation in SSMP. ICM model could be used to predict the porous structure etched by front side illumination on n-type silicon.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Ali Shanaghi, Paul K. Chu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉NiTi alloys are used in orthodontic and orthopedic applications but the long-term corrosion resistance and related properties need improvement in order to satisfy the demand by more stringent applications. In this study, carbon plasma immersion ion implantation (C-PIII) is performed to improve the corrosion resistance and mechanical properties of the Ni〈sub〉50.8〈/sub〉Ti〈sub〉49.2〈/sub〉 (at.%) alloy. The structure, morphology, chemical and mechanical properties, and corrosion resistance are investigated systematically. A uniform, smooth, and crack-free surface layer with a thickness of 50 nm is produced after C-PIII for 2 h. C-PIII also changes the roughness, hardness, and elastic modulus from 17.4 nm, 64.31 GPa, and 2.74 GPa for the pristine NiTi alloy to 6.1 nm, 89.27 GPa, and 4.77 GPa of the C-PIII sample, respectively. Electrochemical impedance spectroscopy (EIS) indicates that C-PIII improves the corrosion resistance and hardness of NiTi. No surface defects are observed and the reinforced surface structure improves the corrosion resistance by 85%. Penetration of corrosive ions during immersion in 3.5% NaCl results in failure of the passive layer but subsequent reactions with titanium re-form the passive layer. The passive layer is more stable at the immersion time point of 96 h and C-PIII also increases the pitting or local corrosion resistance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 365〈/p〉 〈p〉Author(s): Xuanyong Liu, Zengfeng Di, Paul K. Chu, Stephan Mändl〈/p〉

Description: 〈p〉Publication date: 25 May 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 366〈/p〉 〈p〉Author(s): Teresa Moskalioviene, Arvaidas Galdikas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The influence of elastic anisotropy of austenite on the transport of nitrogen in austenitic stainless steel (ASS) during the expanded austenite formation is analyzed by the presented kinetic model. The model is based on the thermodynamics involving the anisotropic lattice expansion due to nitrogen insertion. Thus, a diffusion behavior of nitrogen is affected by not only nitrogen concentration but also the anisotropic stress induced by nitrogen atom expanding the lattice of the steel. Developed model describes well known experimental results for polycrystalline and single crystal ASSs. Using presented model, we studied the effect of crystallographic orientations of single crystal on nitrogen penetration depth and surface concentration during formation of the expanded austenite. It was shown, that the thickness of the nitrided layer depends on the crystalline orientation and the diffusion rate is found to be highest for (100) orientation. Furthermore, anisotropic surface energies of different oriented crystals lead to anisotropy of nitrogen adsorption process. As a result, the (100) crystalline orientation is most favorable for nitrogen diffusion.〈/p〉〈/div〉 〈/div〉