ALBERT

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: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Xiaolin Gong, Xiaorui Zheng, Jiancheng Fang, Gang Liu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Attention has been devoted to distributed position and orientation system (DPOS) which can provide high precision spatial and temporal information for all remote sensing loads for airborne multi-task synthetical earth observation system in recent years. Since there are restrictions of space, weight and cost of the DPOS, it is unrealistic to install an IMU of DPOS at the location of each load, and the optimized layout of DPOS has become an urgent problem should be solved. However, there is no report on the optimized layout method for airborne DPOS yet. In this paper, the optimized layout of DPOS is classified as the optimization problem, and two classical optimization algorithms, the genetic algorithm (GA) and particle swarm optimization (PSO), and two novel optimization algorithms, the particle swarm optimization with mutation (PSOM) and hybrid of PSO and GA (HPSOGA), are used and compared for the first time to determine the optimal layout of DPOS. The mathematical simulation shows that the novel method named HPSOGA is superior to the other three methods. In order to accelerate the convergence rate of this layout method, further mathematical simulation and semi-physical simulation based on flight experiment is carried out and the results show that the calculation amount of this method can be reduced by adjusting the individual number calculated by PSO. The work of this paper can provide new ideas and make a good start for the optimized layout study of DPOS.〈/p〉〈/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: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Xiaotian Chen, Jinzhi Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A new guidance law with both impact time and impact angle constraints is proposed in this paper. We first simplify missile dynamics under small heading error approximation, and derive an optimal guidance law with impact angle constraint against a stationary target. By adding a feedback controller to the obtained optimal guidance law, both impact time and angle requirements are achieved and the singularity problem is tackled. The proposed guidance law can be used to perform a simultaneous formation cooperative attack. Numerical simulations are demonstrated to illustrate the effectiveness of the proposed method.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Kelei Wang, Zhou Zhou, Xiaoping Zhu, Xiaoping Xu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Based on the detailed flow characteristics analyses of a base four-propeller/wing integration at a low Reynolds number of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mn〉3.0〈/mn〉〈mo〉×〈/mo〉〈msup〉〈mrow〉〈mn〉10〈/mn〉〈/mrow〉〈mrow〉〈mn〉5〈/mn〉〈/mrow〉〈/msup〉〈/math〉, new multi-propeller/wing integrated aerodynamic design philosophy and methodology have been developed and validated numerically. The core of the present design philosophy is to make good use of coupling effects between two adjacent propellers to realize the low-Reynolds-number flow-field reconstruction, thus to improve the aerodynamic performance of the multi-propeller/wing integration at the operating power-on state. The multi-reference frame (MRF) technique which quasi-steadily solves the Reynolds-averaged Navier–Stokes (RANS) equations coupled with transition model is used to design the example four-propeller/wing integration at a low Reynolds number of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈mn〉3.0〈/mn〉〈mo〉×〈/mo〉〈msup〉〈mrow〉〈mn〉10〈/mn〉〈/mrow〉〈mrow〉〈mn〉5〈/mn〉〈/mrow〉〈/msup〉〈/math〉. As a result, the designed multi-propeller/wing integration yields a maximum lift-to-drag ratio of 72.81, which represents a 21.08% increase compared to the base four-propeller/wing integration.〈/p〉〈/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: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Xiao Wang, Jie Guo, Shengjing Tang, Shuai Qi, Ziyao Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper proposes an online entry trajectory planning algorithm satisfying terminal full states constraints, path constraints and multiple geographic constraints for lifting-body entry vehicles. The vehicle is considered as a 3DOF point mass. The entry trajectory is divided into the initial descent phase, gliding phase and terminal guidance phase. In the gliding phase, a piecewise polynomial in the altitude-versus-velocity plane is used to plan the longitudinal trajectory and a new heading angle corridor based bank angle reversal logic is designed to satisfy all geographic constraints simultaneously. In the terminal guidance phase, an optimal guidance law with terminal angle constraints is adopted to generate the trajectory. Finally, the terminal full states constraints including terminal velocity direction constraints are implemented by iterating over the altitude in the gliding phase. Then the highly constrained entry trajectory planning problem is converted into a one-parameter search problem. The key of this planning algorithm is the use of terminal guidance phase, through which the terminal velocity direction is constrained strictly rather than kept around the line-of-sight angle and the range error caused by great arc assumption is also avoided. Simulation results with the CAV-H model show that this algorithm can generate entry trajectories satisfying complex constraints rapidly and is suitable for various missions.〈/p〉〈/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: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 358〈/p〉 〈p〉Author(s): Fiorenza Fanelli, Anna Maria Mastrangelo, Gianvito Caputo, Francesco Fracassi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dispersions of oleate-capped ZnO nanoparticles (NPs) in binary 〈em〉n〈/em〉-octane/1,7-octadiene solvent mixtures are injected, in aerosol form, in a dielectric barrier discharge to deposit hydrocarbon polymer/ZnO nanoparticles nanocomposite (NC) thin films at atmospheric pressure and room temperature. The chemical composition of the coatings, and in turn their morphology and wettability, can be tuned by simply changing the composition of the starting dispersion. Specifically, the increase of the NPs concentration in the dispersion (0.5–5 wt%) results in a continuous increase of both the ZnO content and deposition rate of the coatings. Moreover, when the concentration of 1,7-octadiene in the solvent mixture is very low (0.5–2 vol%), the incorporation of NPs is further promoted, while at concentrations 〉2 vol% the growth of the organic component starts to be favored. Overall, results reveal a considerable increase of the root-mean-square (RMS) roughness of the coatings with the ZnO loading. In addition, once the threshold ZnO loading and RMS roughness of 60 wt% and 350 nm are reached, respectively, the coatings are superhydrophobic and exhibit very low water contact angle hysteresis, due to the coexistence of the low surface energy conferred by the hydrocarbon polymer and the hierarchical multiscale surface texture induced by NPs incorporation.〈/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-S0257897218312301-ga1.jpg" width="357" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/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): K. Bobzin, T. Brögelmann, N.C. Kruppe, M. Engels〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Due to their beneficial properties, chromium-based nitride hard coatings deposited by physical vapor deposition (PVD) are applied as protective coatings in many technical applications. In the deposition of these coatings, hybrid dcMS/HPPMS processes consisting of direct current and high power pulse magnetron sputtering can be used in order to benefit from both processes, dcMS and HPPMS. While dcMS provides a considerably higher deposition rate, coatings deposited by HPPMS usually exhibit a significantly higher hardness and show a denser morphology and a smoother surface. The overall aim of this work is to achieve an improved understanding of the hybrid process dcMS/HPPMS. Different nitride (Cr,Al)N coatings were investigated. These were deposited by industrial-like coating processes using an industrial coating unit equipped with six cathodes on the quenched and tempered tool steel AISI 420 (X42Cr13, 1.2083). The aim of the investigations was to analyze the influence of HPPMS on the hybrid dcMS/HPPMS process within the coating plasma at the substrate side and with regard to the deposited coatings. In a first step, the (Cr,Al)N coating plasma was analyzed with a fine spatial resolution along the rotation line of the substrates using dcMS, HPPMS and hybrid dcMS/HPPMS processes. Changes in the plasma composition were investigated from the substrate position using optical emission spectroscopy (OES). In a second step, (Cr,Al)N coatings were deposited using the same process parameters. The coatings were analyzed regarding morphology and deposition rate using scanning electron microscopy (SEM). Furthermore, the contents of Al and Cr in the coatings were analyzed by energy dispersive X-ray spectroscopy (EDS). By comparing the measurements, the influence of HPPMS on the plasma within the hybrid dcMS/HPPMS process was analyzed and compared to the resulting coating properties morphology, deposition rate and chemical composition. This new experimental methodology was introduced before using a large-volume coating unit, but modified with only two cathodes. Within the scope of this work, it was for the first time transferred to an industrial coating unit with six cathodes, different targets and applied under industrial-like process conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Yang Shen, Wei Huang, Tian-tian Zhang, Li Yan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉With the rapid development of aviation and space industry, hypersonic vehicles with high lift-to-drag ratio have attracted an increasing attention. The aerodynamic performance of the aircraft plays a dominant role in the conceptual design of flight vehicles. Based on the sketch of the European EXPERT re-entry vehicle, this investigation provides readers with detailed instructions for the Free Form Deformation (FFD) parametric modeling and aerodynamic optimization of the design of hypersonic vehicles. The aerodynamic characteristics of the vehicle are numerically investigated by the panel method. The Multi-Island Genetic Algorithm (MIGA) is utilized to optimize the aerodynamic shape. The obtained results show that the value of the objective function 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈msub〉〈mrow〉〈mo stretchy="false"〉(〈/mo〉〈mi〉L〈/mi〉〈mo stretchy="false"〉/〈/mo〉〈mi〉D〈/mi〉〈mo stretchy="false"〉)〈/mo〉〈/mrow〉〈mrow〉〈mi mathvariant="normal"〉max〈/mi〉〈/mrow〉〈/msub〉〈/math〉 increases from 0.7141 to 1.4133, and the optimum angle of attack decreases from 21° to 12°. The further analysis digs out the potential effects of the upper and lower surfaces to the vehicle. The impact of the upper surface is greatly diminished. The influence of the body flap, as well as the other objective functions, would be taken into consideration in the oncoming work.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Wen Shi, Juntao Chang, Youyin Wang, Wen Bao, Xiaoyong Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to satisfy the requirement of high integration, the inlet equipped with translating cowl, which is able to adjust the geometries of combustor and inlet simultaneously, is proposed and studied. Numerical investigations are conducted to obtain hysteresis loop, stability boundary and buzz evolution process with various internal contraction ratios in wide range of flight Mach numbers. The dynamic mesh method is utilized to simulate the geometric adjustment. The results reveal that the buzz evolution process has obvious hysteretic characteristics under the change of translating direction. Meanwhile, the mechanism of inlet buzz mode transition is provided. Then, the effects that the translating velocities have on the oscillatory frequency, position of separation leading edge and dynamic drag are given. The higher velocity is able to restrain the intension of separation oscillation and enlarge the stable region, but has insignificant effect on the reduction of oscillatory frequency and dynamic drag. For specific velocities, there is no oscillation. Therefore, the appropriate velocity can be selected for the improvement of inlet stability. This research gives a full insight into the dynamic performance of a hypersonic variable-geometry inlet.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Lang-quan Li, Wei Huang, Li Yan, Zhao-bo Du, Ming Fang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An effective fuel supply strategy with high mixing efficiency, large penetration depth and low stagnation pressure losses determines the overall performance of the scramjet (supersonic combustion ramjet) engine. In this paper, the transverse hydrogen injection flow field with a micro-ramp located upstream of the wall orifice has been investigated numerically based on the code validation. There are four design variables considered in the current study, namely the width, length, and height of the micro-ramp and the distance between the center of the wall orifice and the trailing point of the micro-ramp. Nine cases predicted by the three-dimensional Reynolds-averaged Navier–Stokes (RANS) equations coupled with the two equation 〈em〉k〈/em〉–〈em〉ω〈/em〉 shear stress transport (SST) turbulence model are used for parametric analysis, and the parametric analysis has been carried out by the extreme difference analysis approach. Three optimization cases are obtained, and they have different objectives, namely the minimization of the mixing length, the maximization of the penetration depth and the minimization of the stagnation pressure losses. The flow structures of all cases have been discussed and compared. The quantitative evaluation results of three optimization cases show that the extreme difference analysis approach is an efficient parametric analysis method, and it can obtain the optimal strategy for the micro-ramp within scramjet combustors with the transverse hydrogen jet.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Kun Ye, Zhengyin Ye, Chunna Li, Jie Wu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The hypersonic inlet is more prone to deform when simultaneously subjected to aerodynamic load and harsh aerothermodynamic load. Moreover, the flow field of the hypersonic inlet is sensitive to configuration. Therefore, it is necessary to investigate the effects of the aerothermoelastic deformation on the flow structure and the performance of the hypersonic inlet. This study develops a loose coupling static aerothermoelastic analysis framework based on the CFD/CSD coupling method, and the one-way and the two-way aerothermal-aeroelastic coupling are both used in the analysis. Furthermore, the effects of the aerothermoelastic deformation on the flow structure and the performance of a three-dimensional hypersonic inlet are studied in detail. The reliabilities of the CFD method and the CFD/CSD coupling method are verified by the validation cases of DLR hypersonic inlet experimental model and the HIRENASD experimental model. The results obtained by the coupling methods are similar. However, the aerothermoelastic deformation obtained through the two-way coupling method is relatively larger, and the effects of the deformation on the inlet performance are more obvious. The maximum of the aerothermoelastic deformation exists at the leading edge of the inlet lip. The deformation changes the shock wave structure near the lip, strengthens the shock wave intensity inside the inlet, increases the length of the separated region and the temperature of the external wall, and changes the flow field of the exit. The aerothermoelastic deformation will lead to the increasing of the mass flow coefficient and the pressure rise ratio; however, it will decrease the total pressure recovery coefficient.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Tran Minh Tu, Tran Huu Quoc, Nguyen Van Long〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper deals with free vibration of functionally graded material plates using eight-unknown higher order shear deformation theory in thermal environments. The theory is based on full twelve-unknown higher order shear deformation theory, simultaneously satisfies zero transverse shear stress at the top and bottom surfaces of the FG plate. Heat conduction and temperature-dependent material properties are both taken into account. The temperature field considered is assumed to be a uniform distribution over the plate surface and varied in the thickness direction only. Material properties are assumed to be temperature-dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume power laws of the constituents. Equations of motion are derived from Hamilton's principle. The accuracy of present analytical solution is confirmed by comparing the present results with those available in existing literature. The effects of the temperature field, volume fraction index of functionally graded material, side-to-thickness ratio on free vibration responses of the functionally graded plates are investigated.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Hongwei Han, Dong Qiao, Hongbo Chen, Xiangyu Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Aerocapture, which usually refers to delivering a vehicle from hyperbolic orbit to planetary orbit using the aerodynamic force, can potentially lower fuel consumption. By controlling the direction and magnitude of the aerodynamic force, the vehicle can be accurately transferred to the target orbit. This paper mainly focuses on developing a convex algorithm for the constrained trajectory planning of aerocapture. For nonlinear aerocapture problem, the main task is to convert this problem into a convex sub-problem, and then the solution of the original problem can be efficiently obtained by solving a sequence of such sub-problems with convex optimization. In order to formulate a highly constrained aerocapture trajectory-planning problem into a convex-form one, all non-convex items in aerocapture problem are turned into convex functions by successive linearization, variable equivalent replacement and control variable relaxation. The simulation results of the optimal aerocapture, represented by minimum impulse, flight time and heat load, indicate that the proposed method is highly efficient and can be potentially applied for on-board trajectory planning method.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): K.M. Chung, Kao-Chun Su〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An experimental study was conducted to investigate the effect of swept angle on a compressible convex-corner flow. The freestream Mach number and the convex-corner angle were 0.64–0.89 and 10°–17°, respectively. The swept angle was 5°–15°. The characteristics of a swept convex-corner flow were evaluated from the distributions of both mean and fluctuating pressures. Surface oil flow visualization was also performed to determine the length of shock-induced separated boundary layer. Shock excursion phenomenon was detected by pressure trace and the shock zero-crossing frequency was evaluated using a two-threshold method. A delay in transition from subsonic to transonic expansion flow for a swept case is observed. The effect of swept angle on peak pressure fluctuations and shock Strouhal number is evident.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Junlong Zhang, Juntao Chang, Jicheng Ma, Youyin Wang, Wen Bao〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The flame characteristics of liftoff and attachment in supersonic combustor fueled with liquid kerosene were investigated by the methods of numerical simulation and experiment. A thin strut was equipped in the center of the combustor acting as the flame holder, and the function of fuel injection was also achieved by the thin strut. In the experimental and numerical conditions, the Mach number in the inlet of the combustor is 2.8, with the stagnation state of 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.gif" overflow="scroll"〉〈msub〉〈mrow〉〈mi〉T〈/mi〉〈/mrow〉〈mrow〉〈mi〉t〈/mi〉〈/mrow〉〈/msub〉〈mo〉=〈/mo〉〈mn〉1680〈/mn〉〈/math〉 K, 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si13.gif" overflow="scroll"〉〈msub〉〈mrow〉〈mi〉P〈/mi〉〈/mrow〉〈mrow〉〈mi〉t〈/mi〉〈/mrow〉〈/msub〉〈mo〉=〈/mo〉〈mn〉1.87〈/mn〉〈/math〉 MPa. The flame images during the experiment process are captured by high speed camera, with the camera parameter of 8000 frames per second, and the pressure distributions in the combustor are also recorded by the pressure sensors. Results show that the flame structure could be divided into two statuses, namely flame liftoff status and flame attachment status, and both the equivalence ratio and the plasma jet ignitor could make an influence on the flame status. By analyzing the flow field characteristics obtained by numerical simulation, the formation mechanism of the flame liftoff phenomenon is discussed, and the flame status depends on both the fuel premixed process and flame propagation characteristics. Further, to investigate the influence of equivalence ratio on the flame liftoff characteristic, an experiment with a linearly increasing equivalence ratio from 0.3 to 0.76 is conducted. The hysteresis of flame liftoff distance is found in different equivalence ratio changing paths, and the path response characteristics are probed. The conclusions of this article is helpful for having an understanding of propagation process and revealing the combustion stabilization mechanism in the thin strut-equipped scramjet combustor.〈/p〉〈/div〉

Description: 〈p〉Publication date: 25 January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 358〈/p〉 〈p〉Author(s): Jian Huang, Yuncheng Ma, Kefeng Yao, Chuangsheng Wu, Meng Cao, Jianming Lai, Jijun Zhang, Yan Sun, LinjunWang, Yue Shen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉SnS:In thin films have been deposited on Mo substrates by chemical bath deposition method in acidic solution. The influences of different In-doped concentrations on the morphological, structural, optical properties and phase purities of SnS thin films have been investigated. Many sheet-like particles exist in the deposited SnS:In thin films. The doping of indium will decrease the thicknesses of the deposited thin films. The studies of photo-electrochemical (PEC) properties of SnS:In (In,10 at.%) thin films indicate that their PEC properties are enhanced by the annealing process. The fabrication of Pt/CdS/annealed SnS:In/Mo photocathode can further enhance the photo-current density to 0.790 mA·cm〈sup〉−2〈/sup〉 at −0.4 V.〈/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): Marjan Shahpanah, Somayeh Mehrabian, Marzieh Abbasi-Firouzjah, Babak Shokri〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Plasma-polymerized silicon oxynitride (SiO〈sub〉x〈/sub〉N〈sub〉y〈/sub〉) oxygen barrier thin film was deposited on polyethylene terephthalate substrate by plasma enhanced chemical vapor deposition at low temperature. The deposition reactor utilizes capacitively coupled plasma operating at radio frequency (13.56 MHz). Nitrogen incorporation during the polymerization leads to a SiO〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 dense film with low defects which assists to improve the oxygen barrier properties. The gas mixture of tetraethyl orthosilicate as organosilicon precursor with oxygen and nitrogen gases was used to deposit the transparent polymerized SiO〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 thin films. The effects of nitrogen flow rate on deposition rate, refractive index, surface morphology, surface wettability, chemical structure and binding composition and oxygen permeability of the barrier films were investigated. Moreover, the plasma parameters were monitored by optical emission spectroscopy. SiO〈sub〉x〈/sub〉N〈sub〉y〈/sub〉 oxygen barrier films showed 〈em〉89–91%〈/em〉 transparency. Under the optimal deposition conditions the minimum oxygen permeability of 0.08cm〈sup〉3〈/sup〉/cm〈sup〉2〈/sup〉day bar was obtained.〈/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): Yanlong Wang, Shaoqian Zhang, Yimin Li, Qipeng Lv, Songwen Deng, Gang Li, Yuqi Jin〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Cerium oxide is of crucial importance for intrinsic redox reaction, which is attributed to the active sites neighboring oxygen vacancies. However, the role of oxygen vacancy (Ov) on the various properties of ceria films remains to be elucidated. Herein, ceria films were deposited by magnetron sputtering and the effect of electric current intensity on the creation of Ov was systematically investigated. X-ray photoelectron spectroscopy (XPS) results show that the Ce〈sup〉4+〈/sup〉 concentration decreases with the increase of current intensity, which demonstrates that Ov can be created and tuned during film deposition by controlling electric current intensity. The film fabricated by 6 A current intensity has 42% Ce〈sup〉4+〈/sup〉, approaching that of rhombohedral-Ce〈sub〉7〈/sub〉O〈sub〉12〈/sub〉, which is a stabilized bulk phase ceria. X-ray diffraction patterns reveal that 6 A film shows mixed crystalline phases with the majority of peaks very close to rhombohedral-Ce〈sub〉7〈/sub〉O〈sub〉12〈/sub〉, while 1 A, 2 A, and 4 A ceria films show simple crystalline phase. Raman analysis presents that dioxygen species are heavily absorbed on the surface of 6 A film with more active sites on different crystalline surfaces, which is confirmed by photocatalytic degradation of Methylene Blue. The calculated bandgap by DFT (density functional theory) + U is consistent with that obtained from Tauc plots curves. This work demonstrates that Ov plays an important role on the properties of the ceria film.〈/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): Ying Wu, Yan Liu, Hui Chen, Yong Chen, Hongyu Li, Wei Yi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to reveal the mechanism of microstructure evolution and crack propagation in laser-deposited Stellite 6 alloys, a quenching thermal fatigue test was conducted. Various detection methods were applied to observe differences between the coatings as deposited and after thermal fatigue. The results showed that the 〈em〉γ〈/em〉 → 〈em〉ε〈/em〉 martensitic transformation occurred in the as-deposited 〈em〉γ〈/em〉-Co matrix during the thermal fatigue process, driven by a fast cooling and thermal stress. The generated 〈em〉ε〈/em〉-Co phase presented variant selection, obeying Schmidt's law. In the 〈em〉ε〈/em〉-Co phase, the slip activity derived from different 〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si25.gif" overflow="scroll"〉〈msub〉〈mfenced open="{" close="}"〉〈mrow〉〈mn〉1〈/mn〉〈mspace width="0.25em"〉〈/mspace〉〈mn〉1〈/mn〉〈mspace width="0.25em"〉〈/mspace〉〈mn〉1〈/mn〉〈/mrow〉〈/mfenced〉〈mi〉γ〈/mi〉〈/msub〉〈msub〉〈mfenced open="〈" close="〉"〉〈mrow〉〈mn〉1〈/mn〉〈mspace width="0.25em"〉〈/mspace〉〈mn〉1〈/mn〉〈mover accent="true"〉〈mrow〉〈mspace width="0.25em"〉〈/mspace〉〈mn〉2〈/mn〉〈/mrow〉〈mo stretchy="true"〉¯〈/mo〉〈/mover〉〈/mrow〉〈/mfenced〉〈mi〉γ〈/mi〉〈/msub〉〈/math〉 slipping systems that produced stacking faults and planar defects during the phase transformation. In addition, the stacking faults on {1 1 1}〈sub〉〈em〉γ〈/em〉〈/sub〉 planes promoted the precipitation of directional M〈sub〉7〈/sub〉C〈sub〉3〈/sub〉 fine particle carbides. The net-like eutectic structures and 〈em〉γ〈/em〉/〈em〉ε〈/em〉 interfaces acted as paths for thermal crack propagation.〈/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): Yan Wang, Yongli Zhao, Geoffrey Darut, Thierry Poirier, Jorge Stella, Kuaishe Wang, Hanlin Liao, Marie-Pierre Planche〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Two kinds of cauliflower-like architecture yttria stabilized zirconia (YSZ) coatings with different amounts inter-columnar voids were prepared by suspension plasma spraying (SPS) under different spraying parameters. YSZ coatings with high and moderate porosity were infiltrated with polytetrafluoroethylene (PTFE) in order to form a novel structured ceramic-polymer composite coating. Subsequently, the composite coatings were tribologically evaluated. The tribology behavior of the denser as-sprayed YSZ coatings and pure PTFE coatings were also investigated as reference materials. The results indicated that the composite coatings exhibited a significantly improved wear resistance in terms of a remarkably reduced coefficient of friction and wear rate compared with the as-sprayed YSZ coatings because of the lubricating effect of PTFE. Additionally, it was noted that the existing YSZ framework in composite coatings reinforces PTFE contributing to an even higher wear resistance than that measured on pure PTFE.〈/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): Gerald Womack, Kenan Isbilir, Fabiana Lisco, Geraldine Durand, Alan Taylor, John M. Walls〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉A significant source of energy loss in photovoltaic (PV) modules is caused by reflection from the front cover glass surface. Reflection from the cover glass causes a loss of ~4% at the air-glass interface. Only a single air-glass interface can be coated on crystalline silicon solar modules as an ethylene-vinyl acetate (EVA) layer is inserted between the cover glass and the silicon absorber. A single-layer anti-reflection coating (ARC) on the outer surface of the cover glass is effective at reducing reflection losses over the wavelength range of most PV devices. The coating investigated in this work reduces the reflectance loss at the glass surface by 74%. However, the long-term durability of sol-gel coatings has not been established particularly for use in hot and humid climates. In this work, we investigate the damage resistance of a single-layer closed-surface hard coat ARC, deposited using sol-gel methods by applying a variety of accelerated weathering, scratch and abrasion test methods.〈/p〉 〈p〉The reflectance of the sol-gel ARC was measured and then the coating was put through a series of durability and environmental tests. The coating is resistant to damage from heating and can withstand temperatures higher than the phase change temperature of soda-lime glass. Scratch testing demonstrated that the sol-gel AR is relatively hard and difficult to remove from the substrate surface. Pull tests and cross-hatch testing also confirmed the strong adhesion of the coating. Weathering experiments show some degradation in weighted average reflectance, particularly an increase in reflectance of 0.6–0.9% after 1000 h of exposure to damp heat. Testing also showed a vulnerability to exposure to acid. These results indicate that the performance of this type of ARC could deteriorate and possibly delaminate in humid climate conditions The ARC had a low water contact angle, which means the coatings are hydrophilic and, therefore, hygroscopic increasing the risk of water damage over extended periods of time. This work shows that sol-gel anti-reflection coatings are currently unsuitable for use on PV and are unlikely to remain durable across the 25 year industry standard.〈/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): Desheng Wang, Ming Hu, Dong Jiang, Xiaoming Gao, Yanlong Fu, Jiayi Sun, Lijun Weng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A novel approach by texturing the WS〈sub〉2〈/sub〉 film with the nanocone-array Ni interlayer was adopted to improve the tribological property of WS〈sub〉2〈/sub〉 film particularly prolonging the wear life for application in space. The WS〈sub〉2〈/sub〉/Ni bilayer films were prepared by sputtering WS〈sub〉2〈/sub〉 layer onto electrodeposited Ni interlayers with different surface morphologies. The micro-structures and the tribological properties of the prepared WS〈sub〉2〈/sub〉/Ni bilayer films were investigated. The results showed that with the existence of the nanocone-array Ni interlayer, the textured WS〈sub〉2〈/sub〉 film showed a cabbage-like structure due to the growth of the WS〈sub〉2〈/sub〉 columnar plates surrounding the Ni nanocones. The cabbage-like WS〈sub〉2〈/sub〉/Ni bilayer thin film was benefited for improving the lubrication properties with a long wear life of 4.9 × 10〈sup〉5〈/sup〉 cycles while the wear life was only 0.7 × 10〈sup〉5〈/sup〉 cycles for the pure WS〈sub〉2〈/sub〉 and 3.2 × 10〈sup〉5〈/sup〉 cycles for rough Ni textured WS〈sub〉2〈/sub〉 film. The improved tribological property was mainly attributed to the reserve of the WS〈sub〉2〈/sub〉 lubricate by the Ni nanocones as well as the relative low friction coefficient of the nanocone-array Ni interlayer due to the obvious reduced real contact area.〈/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): Yankun Li, Minfang Chen, Wei Li, Qi Wang, Yansong Wang, Chen You〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Micro-arc oxidation (MAO) as an environmentally friendly technology is used to produce ceramic film on metal surfaces to improve its corrosion properties, and the films quality is mainly affected by the electrolyte composition and electrochemical parameters, Here, to improve the corrosion property and wear-resisting of low carbon steel, a compact, corrosion resistant α-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 ceramic film was prepared on the surface of low carbon steel containing boron (10B21) by MAO. A Na〈sub〉2〈/sub〉SiO〈sub〉3〈/sub〉 and NaH〈sub〉2〈/sub〉PO〈sub〉4〈/sub〉 electrolyte system was designed with different content of Na〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 and Na〈sub〉2〈/sub〉B〈sub〉4〈/sub〉O〈sub〉7〈/sub〉. The ceramic layer produced with Na〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 and Na〈sub〉2〈/sub〉B〈sub〉4〈/sub〉O〈sub〉7〈/sub〉 showed improved corrosion resistance. The corrosion current density was 2.7 μA·cm〈sup〉−2〈/sup〉 and the impedance value reached 1900 Ω·cm〈sup〉2〈/sup〉. After 7 days of neutral salt spray corrosion, the corrosion rate of this sample coating reduced to 53 g·m〈sup〉−2〈/sup〉·h〈sup〉−1〈/sup〉. The influence mechanism is discussed. The cooperation of Na〈sub〉2〈/sub〉CO〈sub〉3〈/sub〉 and Na〈sub〉2〈/sub〉B〈sub〉4〈/sub〉O〈sub〉7〈/sub〉 in the electrolyte is more effectively regulated the ionization and chemical reactions of the MAO process, catalyzing the formation of α-Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉. The coating had a uniform thickness of 100 ± 10 μm, no gap between the coating and the substrate was observed, which indicated that the bonding state was good. Thus, the MAO ceramic layer prepared on low carbon steel surface increases the service life of iron and steel components effectively, which can significantly expand its application in more fields.〈/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): H. Luo, Y.G. Wang, C.Y. Cai, G.W. Zhou, Y.C. Zhou, L. Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Annealing-induced microstructural changes in yttria partially stabilized zirconia (YSZ) have been investigated by scanning transmission electron microscopy combined with computer simulation. It is shown that the high-temperature annealing results in the formation of voids in YSZ and structural ordering in the surrounding area of the voids. Atomic-scale 〈em〉Z〈/em〉-contrast imaging shows one-dimensional distortion of the cation sub-lattice by alternate arrangement of narrow and wide (100) planes of the cation sub-lattice along the [100] direction of the cubic ZrO2 structure. Such distortion of the cation sub-lattice is attributed to the 1/4[001] displacement of the oxygen atoms in the (100) plane, which is confirmed experimentally by annual bright field imaging along with the density-functional theory and computer simulations of the atomic-scale 〈em〉Z〈/em〉-contrast imaging and electron diffraction.〈/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): S. Mirzaei, M. Alishahi, P. Souček, L. Zábranský, V. Buršíková, M. Stupavská, V. Peřina, K. Balázsi, Zs. Czigány, P. Vašina〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Low ductility and brittle deformation behaviors are major drawbacks of currently used commercial hard ceramic-based protective coatings. Recent ab-initio calculations revealed that the coexistence of metallic, boride and carbide bonds in a nanolaminate structure of crystalline W〈sub〉2〈/sub〉BC system provides a combination of high hardness together with moderate ductility. The present paper deals with coatings containing W, B and C with different compositions and investigates the effect of the boron to tungsten ratio (B/W) on the structural and mechanical properties of W-B-C coatings prepared by pulsed-DC magnetron sputtering at a moderate temperature. Coatings with low B/W were deposited in a nanocomposite structure, whereas coatings with high B/W ratios were near-amorphous. The structure of the coatings was not a decisive factor in determining their mechanical properties. These were, however, directly correlated with the chemical bonds present. All the coatings exhibited high fracture resistance. These properties together with good adhesion to cemented tungsten carbides make W-B-C coatings promising candidates for the future protective coatings of tools which undergo large deformation in their working cycle.〈/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): Huiwen Hu, Hongping Wan, Lingqing Dong, Jun Lin, Mohannad Saleh Hammadi Al-Furjan, Kui Cheng, Wenjian Weng, Huiming Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, hydrothermal treatment and ultraviolet illumination (254 nm) were utilized to regulate the surface hydroxyls of titanium dioxide (TiO〈sub〉2〈/sub〉) nanodots films. The effects on light-induced cell detachment behaviors were also investigated and discussed. Scanning electron microscopy, Raman, X-ray photoelectron spectroscopy and Circular dichroism were used to characterize the surface morphology, crystalline phase, surface composition and adsorption conformation of protein molecules. It was found that a combined process of ultraviolet illumination followed by hydrothermal treatment not only promoted cells adhesion but also showed the highest efficiency in light induced cell detachment. The reason is ascribed to that such process promotes the formation of terminal hydroxyl groups in TiO〈sub〉2〈/sub〉 surface, and subsequently affect the adsorption conformation of protein molecules. This study indicated that such treatment could effectively modulate the contents of surface hydroxyl groups in different states. That shows much potential in optimizing the biological performance of TiO〈sub〉2〈/sub〉 based biomaterials.〈/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): X.J. Wu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A crack number density (CND) theory model is developed for air-plasma-sprayed thermal barrier coating (TBC), which describes the evolution of crack number and size distribution as function of exposure time. The model is compared in good agreement with experimental measurements from quasi-isothermal-cyclic oxidation tests. Both the CND model and experimental observations indicate that thermally-grown oxides (TGO) are responsible for crack nucleation and growth. The model can be used to define TBC failure (spallation) by coalescence of microcracks into a maximum allowable crack size with a given probability.〈/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): M.A. Ghasemi, S.R. Falahatgar〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper deals with crack growth simulation in brittle coating/substrate structures under three point bending. For this purpose, a discrete element method (DEM) code is prepared by the authors and is used as a numerical tool with great ability to capture the damages at micro scale. Coating and substrate were considered as isotropic materials. Bilinear cohesive contact model was implemented as bonds between coating and substrate constituent particles. The influence of fracture energy of coating and substrate and coating thickness on the failure of coating/substrate structure is investigated. The results showed that, when the fracture energy in coating and substrate are in the same range, cracks created in the coating were developed to the substrate. But, by increasing the fracture energy in the substrate, interfacial delamination was observed as the failure mode in the structure.〈/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): Kattareeya Taweesup, Patama Visuttipitukul, Niti Yongvanich, Gobboon Lothongkum〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this research, Ti-Cr-N coatings on tool steel were prepared using DC magnetron sputtering at 25 °C (RT), 130 °C and 190 °C. Coating corrosion behavior was observed in a 3.5% NaCl solution at 25 °C using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy (EIS). EIS circuit models for corrosion kinetics were proposed and the surface area and porosity of the coatings were recorded. Corrosion resistance was found to be higher for the coatings grown at 190 °C. This could be attributed to high density as well as low porosity. The EIS circuit model suggests the penetration of corrosive electrolytes into pores reaching the steel substrate for the coatings grown at RT. Finite length diffusion inside pores was also observed. The slow infiltration of corrosive electrolytes into the steel substrate could be seen in coatings grown at 130 °C with diffusion inside the pore similar to that in the coatings grown at RT. However, the EIS circuit model did not exhibit a finite length diffusion of the coatings grown at 190 °C. Owing to high coating density and smaller pore size, corrosive electrolytes could hardly penetrate through and reach the steel substrate.〈/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): Hui Liu, Fu-Chi Yang, Yi-Jing Tsai, Xiaojian Wang, Wei Li, Chi-Lung Chang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The newly developed TiAlSiN/CrN multilayer films were deposited on silicon Si (100) substrates and tungsten carbide steel substrates by high power impulse magnetron sputtering technique (HiPIMS) at 80 °C working temperature. The effect of modulation structure on the microstructural and mechanical properties of thin films was analyzed systematically by TEM, SEM, XRD, nanoindenter, Scratch test, and Rockwell indenter. The grain size of columnar crystals decreases as increasing the Λ from 2 nm to 27 nm. Correspondingly, the crystallite size in the (111) and (200) directions exhibited an increasing tendency, which calculated by the Debye-Scherrer equation. The hardness and Young's modulus exhibited an initial increased with decreasing Λ from 27 nm to 7.5 nm, followed by a decrease. The TiAlSiN/CrN multilayer films with Λ of 7.5 nm reached the highest hardness of 26.6 GPa and the highest Young's modulus of 295.4 GPa. However, the thin film with Λ of 8.5 nm exhibited a hardness value of 25.3 GPa and the highest adhesion strength, which the highest critical load 〈em〉L〈/em〉c1 of 52 GPa and the morphology of Rockwell indentations can be classified as HF1. Therefore, based on both hardness and adhesion strength, an optimization TiAlSiN/CrN multilayer film is in the single layer thickness of 8.5 nm.〈/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): S. Thirumalai, Z.H. Barber, J.A. Williams, A.L. Greer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Iron-rich nanocomposite Fe-Ti-N coatings are deposited by reactive direct-current magnetron sputtering. Co-deposition from two targets (Fe and Ti) onto substrates placed at different locations gives a combinatorial approach to film composition effects, with the Fe/Ti atomic ratio varying from 0.5 to 38. The influence of substrate-temperature is also studied. The nanohardness of the coatings increases with Fe content, and is as high as ~15 GPa, far exceeding the value for pure-iron, and comparable alloy coatings. The nanowear resistance of the coatings scales as expected with their hardness, but their abrasive wear resistance is dependent on their adhesion to the substrate.〈/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): Samia K. Essa, Rong Liu, Matthew X. Yao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉An interfacial fracture toughness model for thermal barrier coatings (TBCs) is proposed in which model parameters not only include the effect of high temperature and exposure period of TBCs but also demonstrate the mode mixity characteristics. The model is expressed in terms of the Arrhenius-type form showing a temperature-dependent feature and also exhibits a dependence of microcrack density distributed along the coating interface. Two scaling parameters are used in formulating the model, one is introduced to link dislocation Burgers vector to the crack tip opening displacement (CTOD), the other is utilized to describe the crack tip energy release rate associated with the P-N force responsible for dislocation movement. These scaling parameters can be obtained by fitting to the interfacial fracture toughness data at ambient temperature and the CTOD, respectively. Since the experimentally measured microcrack density exhibits thermal cycle dependent behavior, an attempt is made to explain the experimentally obtained toughness values using the proposed interfacial crack toughness model. The model predicts an increase in fracture toughness with exposure temperature and mode mixity. The limitation of the model and possible improvement scheme are discussed.〈/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): Hua Zheng, Yina Zheng, Juanhong Wang, Jian Wang, Geng Zhang, Shaoqiao Zhang, Minxia Liu, Jun Hu, Yi Li, Yaohua Hu, Wei Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High-resolution passive-matrix polymer light-emitting displays with printed cathodes are achieved by combining delicate cathode deposition and multifunctional buffer layer fabrication. Unlike other printing methods and printed materials, ink-jetting conducting nano-particles as cathode can provide high-resolution cathode patterns and excellent continuity along the fine cathode lines without any mechanical pressure on the organic layers. The buffer layer between the printed cathode and the organic active layers, was fabricated by mixing the water/alcohol-soluble polymer poly[9,9-bis(3′-(〈em〉N〈/em〉,〈em〉N〈/em〉-dimethylamino)propyl)-2,7-fluorene-alt-2,7-(9,9-dioctylfluorene)] (PFNR〈sub〉2〈/sub〉) and a curable epoxy adhesive. It offers the functions of solvent-proof, electron-injection, and proper affinity with the cathode ink. While improving the performance of devices, especially blocking the leakage current greatly, the cross-linked buffer layer also induces a novel phenomenon of ‘linear 〈em〉η-J〈/em〉 plot’, which can be derived to interesting and realistic results. Red, green, and blue monochrome and full-color polymer light-emitting displays with a content format of 96 × 3 × 64 show neither dead pixels nor dead lines. Under optimized steps of curing, the nano silver ink forms continuous, defect-free, and low-resistance cathode rows without any distortion. The red, green, and blue displays exhibit the current efficiencies of 0.62, 4.38 and 0.93 cd/A, and CIE color coordinates of (0.63, 0.37), (0.39, 0.57) and (0.18, 0.16), respectively. The cathode printing technique removes the need of high vacuum for thermal evaporation of the cathode metal, which could lead to the industrial roll-to-roll process to manufacture the flat panel displays.〈/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): Shi-hang Kang, Wen-bin Tu, Jun-xiang Han, Zhi Li, Ying-liang Cheng〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Titanium alloys own a series of advantages such as low density, high specific strength, and biocompatibility. However, the poor wear resistance of titanium alloys impedes their wide applications in industry. In this study, we show that the wear resistance of the Ti6Al4V alloy can be greatly improved by a combined method of magnetron sputtering and plasma electrolytic oxidation (PEO). An ~13 μm pure aluminum layer was first applied on the Ti6Al4V alloy by magnetron sputtering and then PEO was employed for the second step treatment of the Al coated Ti6Al4V alloy. The PEO of the Al coated Ti6Al4V was carried out in aluminate (32 g l〈sup〉−1〈/sup〉) and silicate (16 g l〈sup〉−1〈/sup〉) electrolytes, respectively. Ball-on-disc tribological tests with an applied load of 10 N against a Cr steel ball were used to evaluate the wear performances of the samples. The coating formed in 32 g l〈sup〉−1〈/sup〉 aluminate electrolyte for 4 min shows superior wear performance, which sustained 1800 s sliding time against the steel ball and the wear rate is non-detectable. In contrast, the coating formed in the silicate electrolyte for 15 min has been destroyed during the tribological test, showing a wear rate of ~3.9 × 10〈sup〉−4〈/sup〉 mm〈sup〉3〈/sup〉/(N·m). The excellent wear performance of the coatings formed in the aluminate electrolyte can be attributed to its high growth rate and homogeneity in microstructure. The coating growth mechanisms have also been discussed.〈/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): Yiqi Wei, Yinglin Yan, Yiming Zou, Mangmang Shi, Qijiu Deng, Nana Zhao, Shiyu Chen, Jiaming Lin, Rong Yang, Yunhua Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Lithium-sulfur (Li-S) battery processes high theoretical capacity (1675 mA h g〈sup〉−1〈/sup〉) and energy density (2600 Wh kg〈sup〉−1〈/sup〉), which was widely accepted as one of the most promising candidates for energy storage devices. In this presented study, bamboo-derived hierarchical porous carbon (BDPC) was adopted as a conducting substrate for containing S. Soft polystyrene (PS) and polyaniline (PANI), were prepared as coating layers. The main purpose is to figure out the specific roles that the polymer shells and the heteroatoms doped on polymer backbone play during cycles. The ternary products were characterized by structural analysis and electrochemical testing. The results indicate that, as compared to BDPC/S, the PS@BDPC/S electrode displays higher capacity retention during long-term cycles, especially at the high current rate. It is attributed to the integrated coating shell, which provides physical confinement and reserves spaces for restraining volume expansion. It is noted that the PANI@BDPC/S electrode presents a higher initial capacity, remarkable long-life performance, and excellent rate property. The outstanding performances are closely related to the nitrogen atom doped on PANI backbone, they provide not just abundant polar conducting sites for fast electron/Li-ion transport but strong chemical anchoring for restricting the migration of polysulfides. Therefore, our study poses a clearer understanding of the functionalized polymers used in Li-S battery.〈/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): Liang-Yu Chen, Tianxiang Xu, Haiyang Wang, Peng Sang, Sheng Lu, Ze-Xin Wang, Shujin Chen, Lai-Chang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Although considerable endeavors have been dedicated to investigate the microstructures of the remelting-enhanced NiCrBSi coatings, the textures in the remelted coatings, which may result in property anisotropy, are rarely studied. In this work, the recrystallized fractions, grain orientations and interphase boundaries for Ni, Ni〈sub〉3〈/sub〉B and CrB in a plasma sprayed-remelted NiCrBSi coating were investigated by electron backscatter diffraction. The results demonstrate that the texture is induced by phase interaction during solidification. Cooling from the liquid, the firstly formed Ni grains possess a cube fiber texture of {001}〈001〉. The successively formed Ni〈sub〉3〈/sub〉B colonies are randomly oriented and keep specific orientation relationships with the surrounding Ni grains, resulting in formation of some weak texture components of Ni. The finally formed CrB grains have a considerably high frequency (40.8%) of lattice correlation boundary of (002)〈sub〉Ni〈/sub〉//(040)〈sub〉CrB〈/sub〉, but no specific orientation relationships with Ni〈sub〉3〈/sub〉B grains. Hence, the interaction of Ni and CrB grains leads to the formation of more texture components of Ni. As such, the phase interaction induced texture forms in the remelted NiCrBSi coating. This work would give an insight into the anisotropy in the remelted NiCrBSi coatings and provide a theoretical basis of further optimizing the remelting process technologies.〈/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): Yingying Zhang, Xiong Li, Denghui Xu, Fanwen Meng, Rong Hu, Jia Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Solvent additive can effectively regulate the phase-separated morphology of the active layer and improve the power conversion efficiency of polymer solar cells. In this study, the influence of solvent additives 1,8-dichlorooctane (DClO), 1,8-dibromooctane (DBrO) and 1,8-diiodooctane (DIO) on the morphology of PTB7:PC〈sub〉71〈/sub〉BM active layer films is investigated systematically, and the photovoltaic performance of the prepared bulk heterojunction polymer solar cells is analyzed detailedly. The DIO and DBrO additives facilitate PC〈sub〉71〈/sub〉BM diffusing into the PTB7 polymer network and forming interpenetrated bulk heterojunction junction morphology, while the DClO additive deteriorates the active layer morphology. The optimized morphology of DIO and DBrO additives promotes exciton dissociation efficiency, improves charge transport and collection efficiency. The optimum performances were obtained in the devices with DIO additive.〈/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): H. Kovacı, İ. Hacısalihoğlu, A.F. Yetim, A. Çelik〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In recent years, hybrid surface treatments which include plasma nitriding combined with pre-shot peening operations have been proposed for the improvement of nitriding efficiency. The main objective of this study is to characterize the effects of dual process on the friction and wear behavior of metallic materials. For this purpose, AISI 4140 steel samples were shot peened at various densities of 16, 20 and 24 A. The pre-treated samples were plasma nitrided at a temperature of 500 °C for 1 and 4 h. The structural and mechanical properties of samples were analyzed by XRD, SEM and microhardness tester. Wear tests were performed under dry sliding conditions to determine the tribological properties of the samples. This study showed that the shot peening treatment formed finer grains, compressive residual stresses on the surface and increased the diffusion kinetics of the samples. The surface hardness and residual stresses increased with increasing shot peening density. It was evidence that the finer grains, increased dislocation density and surface defects increased the case depth obtained from plasma nitriding by enabling easier diffusion of nitrogen. The depth of the diffusion zones in shot peened plus plasma nitrided specimens was found almost two times thicker than that of the diffusion zones in specimens treated only by plasma nitriding. The highest surface hardness values were obtained from pre shot peened and plasma nitrided samples in consequence of the interactive effect from nitride phases/layers and increased surface compressive residual stress. As a result, pre-shot peened plus plasma nitrided samples exhibited higher wear resistance than specimens treated only by shoot peening and hybrid treating in glow a discharge atmosphere.〈/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): Maksim Krinitcyn, Gennady Pribytkov, Victoria Korzhova, Irina Firsina〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Coatings obtained by electron-beam overlaying of “titanium - titanium carbide” composite powders were investigated. The composite powders have been prepared by self-propagating high-temperature synthesis (SHS) in titanium and carbon reactive powder mixtures. Structural studies of the powders synthesized and of the clad coatings were carried out by X-ray diffractometry, optical metallography, and scanning electron microscopy. The coatings were tested on hardness and abrasive wear resistance. Testing results were discussed in the combination with structure investigation results.〈/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): L. Cen, W.Y. Qin, Q.M. Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The interface delamination plays an important role in failures of thermal barrier coatings. An axisymmetric finite element model was built for air plasma sprayed thermal barrier coatings. The model incorporated a Fortran subroutine developed for the TGO growth. It is found that the stress conversion happens in the top-coat at high temperature under isothermal exposure. A simple numerical method was proposed to calculate the normal and tangential stresses at the top-coat/TGO interface and the bond-coat/TGO interface. The bond-coat/TGO interface is less likely to separate during thermal exposure because the interfacial stresses are limited mostly by the high-temperature yield strength of the bond-coat. The delamination of the bond-coat/TGO interface happens on cooling, which is supported by the experimental observation. As a result, the delamination of the bond-coat/TGO interface could be appreciated based on the corresponding normal and tangential stresses.〈/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): Qi Yang, Wenlong Zhou, Xiaobing Zheng, Zhiqiang Niu, Zhiqiang Li, Bowei Zou, Xuesong Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Dovetail joint specimens manufactured from the Ti-6Al-4V alloy were designed and used to investigate the fretting fatigue behavior of the blade/disk interface in gas turbine engines. Shot peening was combined with plasma-sprayed CuNiIn coating to improve the fretting fatigue resistance of the specimens. The finite element models were used to analyze the contact stress distribution in the fretting area. A plastic layer was added to simulate the CuNiIn coating that was sprayed on the surface of the dovetail blade. The fretting cracks tended to initiate at the contact edge, where the high stress concentration existed, and severe fretting wear damage occurred. The CuNiIn coating modified the local stress distribution under the fretting condition and mitigated the stress concentration degree of the contact edge. The surface strain hardening layer and the compressive residual stress were induced by the shot peening treatment, which promoted the wear and the fatigue resistance of the Ti-6Al-4V substrate under the fretting condition. The fretting fatigue property of specimens improved after the combined surface treatment.〈/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): Ma Guozheng, Chen Shuying, He Pengfei, Wang Haidou, Zhou Yangyang, Zhao Qing, Li Guolu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to optimize the supersonic plasma spraying process more scientifically, it is important to clearly understand the spreading behavior of molten droplet. In this study, the effects of spray parameters on the in-flight behavior and spreading behavior of Fe-based amorphous droplets were investigated. Additionally, since the morphology of the splats is a very important factor which determines the final properties of the coatings, the splats in this study were characterized in terms of their circularity, eccentricity, solidity, and spread factor. The porosity and micro-hardness of the Fe-based amorphous coatings were also evaluated. Results show that the spraying power is the most important parameters that influence the surface temperature of the Fe-based amorphous droplets, while the main factor affecting the in-flight velocity is the Ar flow rate. The melting index of in-flight particles reaches the maximum value at the spraying power of 60 kW and Ar flow rate of 110 L/min. The droplets present disk-shaped splats with the lowest solidity and eccentricity, and highest circularity and spread factor with the average velocity of 445 m/s and surface temperature of 2780 K. This is very crucial to reduce the defects of as-sprayed coatings and form fine-lamellar-structured supersonic plasma-sprayed coatings with outstanding mechanical properties.〈/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): Qingyu Hou, Xiaoyu Ma, Rongcheng Lu, Wei Wang, Ping Wang, Zhenyi Huang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tungsten-based coatings without TiC addition (TiC-free) and with 1.5 wt% TiC addition (TiC-doped) were fabricated by supersonic atmospheric plasma spraying (SAPS) technique, respectively. The as-sprayed coatings were then irradiated by laser. The results showed that the as-sprayed coatings were mainly composed of lamellar structure. TiC phase located mainly at lamellar gaps of the as-sprayed TiC-doped coating with a morphology of strip filled the gaps. The as-sprayed TiC-doped coating exhibited dense structure, lower porosity, reduced oxygen content and higher thermal conductivity as compared with the as-sprayed TiC-free coating. The as-irradiated coatings could be divided into remelted zone, un-remelted zone and/or mixing zone. Cracks were more easily formed in the as-irradiated TiC-free coating than in the as-irradiated TiC-doped coating. The stripped TiC phase in the as-sprayed TiC-doped coating changed into quasi-spherical/spherical ones in the remelted zone of the irradiated coating and distributed along the tungsten grain boundaries. The averaged tungsten grain size in the remelted zone of the as-irradiated TiC-doped coating was about 5.4 μm and that of the as-irradiated TiC-free coating was about 14.8 μm. There were about 96 wt% α(W) and about 4 wt% γ(W) existed in the remelted zone near the surface of the as-irradiated TiC-free coating. Only α(W) could be received in the remelted zone far from the surface of the as-irradiated TiC-free coating and the remelted zone of the as-irradiated TiC-doped coating. There were no obvious diffraction peaks for γ(W) could be indexed from the XRD patterns for the as-irradiated TiC-doped coating. The ability of the as-sprayed TiC-doped coating to resist laser irradiation was greater than the as-sprayed TiC-free coating, mainly attributing to the higher thermal conductivity of the as-sprayed TiC-doped coating and the refinement effect of TiC particles in the as-irradiated TiC-doped coating.〈/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): Xian-Feng Ma, Ya-Wen Wu, Jie Tan, Chui-Yi Meng, Liu Yang, Wei-An Dang, Xiu-Jie He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To develop a nuclear fuel cladding that has high tolerance under normal operating conditions and accident conditions, TiAlCrN coatings were deposited onto Zr substrates by multi-arc ion plating technique. After a corrosion test in static pure water at 360 °C and 18.5 MPa, the TiAlCrN coating showed no obvious spallation and had a weight gain of one order of magnitude less than that of the uncoated Zr sample. The decomposition and oxidation of the TiAlCrN coating at high temperature is an endothermic and exothermic reaction, respectively. Owing to the oxidation in the coating, the formed oxide layers reduce the oxygen penetration through the coating and also reduce the thickness of the zirconia layer from 300 μm to 10 μm at 1060 °C in air. This work lays the foundation for the next oxidation of TiAlCrN coating in high temperature steam, and demonstrates that TiAlCrN is a promising candidate material for the development of nuclear fuel cladding.〈/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): Xiaolan Zhang, Xiaoxu Liu, Chen Yang, Na Li, Tianyi Ji, Kai Yan, Bo Zhu, Jinghua Yin, Jiupeng Zhao, Yao Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Hard carbon with high special capacity has been widely studied as anode for sodium ion batteries (SIBs). Its storage sodium performance still needs to be further improved. Herein, a composite electrode was synthesized through growing V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanosheet array on free-standing hard carbon fiber fabric by solvothermal reaction. The electrochemical properties of the composite electrode were significantly enhanced compared with pure hard carbon fiber electrode. The composite showed a specific capacity from 241 mA h g〈sup〉−1〈/sup〉 at 50 mA g〈sup〉−1〈/sup〉 to 77 mA h g〈sup〉−1〈/sup〉 at 1000 mA g〈sup〉−1〈/sup〉 and a good cycling ability of 184 mA h g〈sup〉−1〈/sup〉 after 100 cycles at 100 mA g〈sup〉−1〈/sup〉. Except good storage Na ability for V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nannosheets, the improvement of electrochemical performances also benefited from and the synergistic effect from the ability of fast electron transfer of hard carbon and the toleration for Na〈sup〉+〈/sup〉 insertion of V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 nanosheet array, as well as the inhibitory effect on solid electrolyte interface (SEI) of nanostructure. Additionally, the free-standing electrodes could also increase the energy and power density. This will push the promising hard carbon material used as SIBs anode in practical applications.〈/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): De Wang, Wenqin Wang, Mingsheng Wang, Yulong Li, Xingui Chen, Changtai Chi, Yujiang Xie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉NiCoCrAlYTa-Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 metal matrix composite coatings were prepared on single crystal superalloy by electrospark deposition (ESD) to improve the wear- and oxidation resistance. The effect of operating voltage during ESD on the deposit morphology, coating growth kinetics, microstructure and properties was investigated. The results showed that, with increasing operating voltage, the dimension (both diameter and depth) of single-pulse deposit increased, leading to thinner deposit thickness, thus resulting in higher cooling rate, finer grains, stronger crystal orientation, and increasing microhardness. Whereas the motion of the molten deposit metal became more turbulent, giving rise to the defect of lack of fusion. However, the grain size increased obviously from bottom layer to top layer for 100 V condition, leading to decreasing microhardness. Meanwhile, the mass gain rate increased but the mass transfer coefficient decreased with the increase of operating voltage. The distribution pattern of Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 particles changed during electrospark deposition, from gathering in the boundary between the powders in the electrode to distributing homogeneously in the whole coating, which contributed to the increase of coating microhardness.〈/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): Xuan Zhang, Yanli Zhong, Yue Yan, Zhongqi Huo, Changshan Hao, Jingjing Peng, Guanli Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Three types of primer layers, including polyurethane (PU), acrylic, and silicone coatings, were developed and deposited on the poly(methylmethacrylate) (PMMA) substrates. Amorphous transparent indium zinc oxide (IZO) films deposited by direct current magnetron sputtering at room temperature on primer-treated and untreated PMMA substrates were investigated ex situ in terms of surface morphology, adhesion, nanoindentation and electrical properties. AFM images show that the microstructure of IZO films was determined by the morphology of the primer layers. IZO films deposited on silicone and acrylic-treated PMMA substrates presented the least surface roughness, which proved that the silicone and acrylic primer layers were more effective to get a dense surface. Nano-scratch tests indicated that the adhesion of IZO films deposited on substrate treated by silicone-based primer layers was superior to that on PU-treated and untreated substrate, which can be attributed to the better mechanical matches of the IZO/primer/PMMA system and the large values of hardness of the silicone primer, which can counterbalance the indentation load and prevent the failure of the films.〈/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): Guang-Xing Liang, Yan-Di Luo, Ju-Guang Hu, Xing-Ye Chen, Yang Zeng, Zheng-Hua Su, Jing-Ting Luo, Ping Fan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the influence of annealed ITO thin film as a transparent electrode layer in pulse laser deposition (PLD) Cu〈sub〉2〈/sub〉ZnSnS〈sub〉4〈/sub〉 (CZTS) thin-film solar cell was investigated. The proposed annealed ITO thin film exhibits a high degree of crystallinity and large and evenly distributed grains. Thus, low resistivity and wide and high transmitted band in the UV/VIS light range with ideal optical band gap of 3.8 eV can be obtained. Devices built with these annealed ITO thin films on our PLD CZTS solar cell exhibit a significant improvement in power conversion efficiency from 0.2% to 1.92%.〈/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): Fan Wang, Guang-Nan Luo, Jianjun Huang, Ying Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tungsten coatings were deposited onto oxygen-free copper substrate by atmospheric plasma spraying technique. Annealing treatment was adopted to modify the inherent defects and improve the performance of the plasma sprayed tungsten coating. The effect of annealing under vacuum and hydrogen atmosphere on the properties of plasma sprayed tungsten coating was studied. The results show that the tungsten grains grow up after annealing treatment, the coatings are transformed from a disorganized structure into a columnar crystal structure with an orderly arrangement. Annealing treatment at a certain temperature can decompose and reduce the tungsten oxide in the coating into pure tungsten, thereby reducing the oxygen content and improving the purity of the coating. As a result, the thermal conductivity, microhardness and other performances of the APS-W coating are improved after annealing.〈/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): L.L. Zhai, C.Y. Ban, J.W. Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉External signal steady magnetic field and electric-magnetic compound field were applied to investigate the influence of the electromagnetic field to the laser cladding NiCrBSi coatings. The macromorphology, phase composition and microstructure were identified by optical microscope (OM), confocal scanning laser microscope (CSLM), X-ray diffraction (XRD) and scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS). The experimental results demonstrated that the main phase composition of the coatings was γ-(Fe,Ni), Cr〈sub〉23〈/sub〉C〈sub〉6〈/sub〉, Cr〈sub〉7〈/sub〉C〈sub〉3〈/sub〉, CrB, Ni〈sub〉3〈/sub〉B with and without electromagnetic fields. Results showed that the dilution of the coating under electric-magnetic compound field was similar (14%) to the coating without auxiliary field. While the dilution of the coating had a decrease (10.8%) under signal steady magnetic field. Results of microstructure indicated the content of CrB phase in the coating increased obviously under electromagnetic field. The average microhardness of the coating under electromagnetic field was increased compared to that of the coating without auxiliary field. Corrosion resistance was also improved under electromagnetic field auxiliary laser cladding.〈/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): Jia-Hong Huang, You-Fu Chen, Ge-Ping Yu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The objectives of this study were to evaluate the fracture toughness of Ti〈sub〉1-x〈/sub〉Zr〈sub〉x〈/sub〉N hard coatings using the internal energy induced cracking (IEIC) method and to investigate the compositional effect on the fracture toughness, from which the optimum composition for fracture toughness could be attained. Ti〈sub〉1-x〈/sub〉Zr〈sub〉x〈/sub〉N was selected to be the model system, because Ti〈sub〉1-x〈/sub〉Zr〈sub〉x〈/sub〉N remained single phase structure in the entire compositional range at deposition temperature below 500 °C. Three compositions of Ti〈sub〉1-x〈/sub〉Zr〈sub〉x〈/sub〉N coatings, x = 0.25, 0.55 and 0.85, were deposited by unbalanced magnetron sputtering. The parameters of IEIC method included the residual stress determined by the laser curvature method, Young's modulus obtained from nanoindentation and the film thickness measured from SEM cross-sectional image. The residual stress and film thickness before specimen fracture were used to calculate the elastic stored energy (G〈sub〉s〈/sub〉), from which the fracture toughness (G〈sub〉c〈/sub〉) could be derived. The resultant G〈sub〉c〈/sub〉 of the Ti〈sub〉1-x〈/sub〉Zr〈sub〉x〈/sub〉N coatings varied with Zr fraction, ranging from 26.0 to 48.7 J/m〈sup〉2〈/sup〉, and reaching a maximum at a composition of Ti〈sub〉0.15〈/sub〉Zr〈sub〉0.85〈/sub〉N. The results showed that adding Zr atoms into TiN could effectively increase the fracture toughness. The maximum increase of fracture toughness lay in the intermediate range of composition (Zr = 0.55–0.85), suggesting that different properties of Ti and Zr atoms may play an important role on the fracture toughness of single phase Ti〈sub〉1-x〈/sub〉Zr〈sub〉x〈/sub〉N thin films. The increase of G〈sub〉c〈/sub〉 with Zr composition may be correlated with the change of configurational entropy of the Ti-Zr-N system. The atomic size difference of Zr and Ti may be crucial on increasing fracture toughness. The increase of fracture toughness for Zr-dominant Ti〈sub〉0.15〈/sub〉Zr〈sub〉0.85〈/sub〉N coating was higher than that for Ti-dominant Ti〈sub〉0.75〈/sub〉Zr〈sub〉0.25〈/sub〉N coating. This asymmetrical behavior could be attributed to the difference in lattice constants between Ti-rich and Zr-rich compounds, where the capability of increasing G〈sub〉s〈/sub〉 may be higher for a smaller Ti atom incorporated into a larger Zr site in ZrN lattice.〈/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): Yuanlin Xue, Wenge Chen, Qian Zhao, YongQing Fu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉For carbon fiber reinforced metal matrix composites, there are many potential problems such as severe agglomeration of carbon fibers (CFs), their poor interfacial wettability with the matrix, and poor mechanical strength. To solve these problems, we proposed to use electroless plating to coat a layer of Ni onto the CFs, and then studied their interfacial structures, fracture strain/strength and wettability. The coated Ni layer was uniformly distributed onto and well bonded with the CFs. The maximum strain of the CFs coated with the Ni layer was increased by 23.4%, though their average fracture strength was slightly decreased from 3.5 GPa to 2.25 GPa. The wettability of the Ni-coated fiber was significantly improved, verified from testing results using both a dip coating method and a fiber reinforced composite simulation test.〈/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): Rui-ting Tong, Bin Han, Ze-fen Quan, Geng Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this paper, a molecular dynamics model is proposed to describe the collision friction of a hinge mechanism in the space environment. The EAM potential is used to describe the interaction between atoms. Based on the model, the collision friction process and thermal properties between the indenter and smooth gold film surface at different indenter amplitudes, frequencies and crystal orientations are studied. The temperature distribution and collision friction mechanism of the gold film are analyzed. The simulation results show that increasing the vibration frequency of the indenter in a certain frequency range can reduce the friction force. The amplitude of the indenter and crystal orientations at different frequencies shows different effects on the average friction force and the surface temperature of the substrate. In addition, textures are also made on the gold film and the effects of texture width and texture depth on the friction and thermal properties are investigated. The results show that the textured surface can significantly reduce the friction force. The average friction force and the surface temperature of the substrate decrease with the increase of texture depth, and increase with the increase of texture width. The average friction force and the surface temperature of the substrate are more sensitive to the texture depth.〈/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): Yan Tang, Fang Wu, Liang Fang, Ting Guan, Jia Hu, ShuFang Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Layered double hydroxides (LDHs) have great potential as protective coatings on magnesium alloys due to their nanolamellar structure and exchangeability of interlayer anions. ZnAl layered double hydroxides films intercalated with nitrate anions (ZnAl-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉-LDHs) was synthesized on the AZ31 magnesium alloy by hydrothermal method. In order to obtain better corrosion resistance, ZnAl-X-LDHs (X = Cl〈sup〉−〈/sup〉, VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉, PO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉, or MoO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉) were prepared by using ZnAl-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉-LDHs as a precursor, and Cl〈sup〉−〈/sup〉, VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉, PO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉, and MoO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉 anions intercalated into the LDHs interlayers to replace NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 through anion-exchange reaction. X-ray diffraction (XRD), scanning electronic microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy were used to investigate structure, morphology and composition of the ZnAl-LDHs. The corrosion resistance of ZnAl-LDHs intercalated with different anions was compared by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results show that the corrosion resistance of ZnAl-LDHs films is ranged in order as follows: ZnAl-VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉-LDHs 〉 ZnAl-MoO〈sub〉4〈/sub〉〈sup〉2−〈/sup〉-LDHs 〉 ZnAl-PO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉LDHs 〉 ZnAl-Cl〈sup〉−〈/sup〉LDHs 〉 ZnAl-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉LDHs. ZnAl-VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉-LDHs has the largest basal spacing distances d〈sub〉(003)〈/sub〉 value and strongest ability to release anions and absorb chloride ions, so ZnAl-VO〈sub〉4〈/sub〉〈sup〉3−〈/sup〉-LDHs films has the optimal corrosion resistance and can provide enhanced anticorrosion protection for magnesium alloys substrate.〈/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-S0257897218312805-ga1.jpg" width="301" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/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): Elia Vidal, Judit Buxadera-Palomero, Camille Pierre, José M. Manero, Maria-Pau Ginebra, Sophie Cazalbou, Christèle Combes, Elisa Rupérez, Daniel Rodríguez〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Metallic implants have some limitations related to bioactivity and bacteria colonization leading to infections. In this regard, calcium phosphate coatings can be used as carrier for drug delivery in order to improve the mentioned drawbacks. The present work proposes the introduction of an antibacterial agent in the course of a pulsed and reverse pulsed electrodeposition. Calcium phosphate coatings were prepared in 30 min using different pulse waveforms (unipolar-bipolar), current densities (2–5 mA/cm〈sup〉2〈/sup〉) and temperatures (40–60 °C). Mechanical stability of the as-coated surfaces was studied in order to select the optimal electrodeposition conditions. Subsequently, selected coatings were loaded with an antiseptic agent, chlorhexidine digluconate (CHX), 〈em〉via〈/em〉 a single-step co-deposition procedure. CHX concentration added to the electrolyte was adjusted to 3 mM based on the antibacterial efficacy of the loaded coatings evaluated 〈em〉in vitro〈/em〉 with 〈em〉Staphylococcus aureus〈/em〉 and 〈em〉Escherichia coli〈/em〉 bacteria strains. Whereas the same chlorhexidine concentration was added to the electrolyte, results showed that the amount of CHX loaded was different for each condition while release kinetics was maintained. The results of this work demonstrate that a pulsed co-deposition strategy has great potential to modulate local delivery of antibacterial agents such as chlorhexidine digluconate, which may prevent early phase infections of metallic implants after insertion.〈/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-S0257897218312477-ga1.jpg" width="500" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/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): Shuwei Ge, Bizhuang Zhang, Chengtao Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Er-doped AlN thin film was deposited on sapphire substrates (0001) by RF magnetron sputtering at different sputtering times. The crystalline structure, surface morphology and electrical properties of the thin films have been investigated. The XRD patterns and the SEM sectional diagram indicate that Er-doped AlN thin films present the preferred orientation of C axis. The crystalline quality of the films rises first and then decreases with the increase of sputtering time and reaches best at 90 min. Piezoelectric coefficient d〈sub〉33〈/sub〉 indicates maximum value of 9.53 pm/V. Correspondingly, the best surface morphology of thin film was obtained at 90 min and the surface roughness reached a minimum of 2.012 nm. In addition, the change of resistance is same with change of the crystalline quality and the resistivity reached a maximum of 4.36 ∗ 10〈sup〉12〈/sup〉 Ω·cm at 90 min.〈/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): V.A. Burdovitsin, D.A. Golosov, E.M. Oks, A.V. Tyunkov, Yu.G. Yushkov, D.B. Zolotukhin, S.M. Zavadsky〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉We describe a novel method for electron-beam nitriding of metal (titanium) under medium (fore-vacuum) pressures (2–8 Pa) of nitrogen. Titanium sample was heated by a dc electron beam generated by a fore-vacuum plasma-cathode electron source with current up to 100 mA and energy up to 8 kV; this beam also generated beam-produced plasma with active nitrogen atoms, ions and other reactive species near the sample. SEM chemical composition analysis of the nitride layer have shown the presence of approximately 25 wt% of N, wt. 68% of Ti and only wt. 6% of O atoms within the processed layer. The X-ray diffraction spectrum of the nitride sample showed that the modified layer has a crystalline structure predominantly orientated along the crystallographic directions (111), (200), (220), characteristic of δ-TiN with a face-centered lattice. Besides the δ-TiN phase, there are present in the nitrided layer a γ phase of Ti〈sub〉2〈/sub〉N (tetragonal nitride) with predominant orientation (200). These results show the advantage of using forevacuum sources for electron beam and plasma nitriding of metals.〈/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): Stefan Saager, Bert Scheffel, Olaf Zywitzki, Thomas Modes, Markus Piwko, Susanne Doerfler, Holger Althues, Christoph Metzner〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Porous silicon thin films were fabricated by an innovative method using vacuum processing for the application as high capacity anode in lithium ion batteries. The deposition procedure comprises a co-evaporation of silicon and zinc, resulting in a deposition of a compound layer with deposition rates up to 100 nm/s and a subsequent thermal annealing. Due to its high vapor pressure, the zinc fraction is expelled and hence, a porous silicon matrix is formed. Herein, we introduce a novel and potentially scalable synthesis method for porous silicon films and show first analytical investigations concerning the layer morphology and the electrochemical properties. With the novel silicon anode excellent electrochemical performance, particularly high capacities of ≥3000 mAh/g, reasonable coulombic efficiencies of ≥90% in the initial cycle and comparably high cycle life 〉150 cycles can be demonstrated, which reveals their great potential for battery anode applications.〈/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-S025789721831274X-ga1.jpg" width="249" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/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): K.A. Habib, D.L. Cano, José Antonio Heredia, J.S. Mira〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The purpose of this paper is to understand and to quantify the effect of the re-melting technique on the microstructure and tribological behaviour of oxy-fuel (OF) thermally sprayed NiCrBSi coatings in the mixed lubrication regime. Two different re-melting techniques have been used: Surface Flame Melting (SFM) and laser re-melting processes. The microstructure of the obtained coatings was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Deposited coatings demonstrated similar phases but manifested notable differences in their morphology, size, distribution and relative proportions of the observable phases. These differences in microstructure may explain the differences in coating properties. Tribological experiments were carried out using a pin-on-disc approach at different sliding speeds and contact pressures. Wear and indentation tests have also been conducted. Laser re-melted coatings achieve higher hardness, less friction and lower accumulated wear volume in lubricated conditions. Test data were fitted with regression models. The fitted equations allow a robust assessment of the effect of the re-melting technique and working conditions on the friction coefficient in components that operate in the mixed lubrication regime. Therefore, these equations may help to select the adequate coating and tribological parameters for specific applications.〈/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-S025789721831315X-ga1.jpg" width="306" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/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): Jian Chen, Hong Hu, Yindong Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Recently, microchannel jetting dispenser technology has been widely used in many industrial applications such as an assembly of micro-electronics. The microfluidic channel of the dispensing needle affects significantly the jetting dispensing process. In order to increase the insufficiency and instability of contact inkers, the novel microchannel structure with the diamond film coating was proposed in this paper. The surface morphology, structure and hardness of the TiAIN films have been observed. The TiAIN film coating can enhance the tightness and stability and shows the improvement in the non-contact dispensing process. The experimental investigation about the effect of the nozzle with TiAIN film coating was provided in this study.〈/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): Longcheng Yin, Xinxin Ma, Guangze Tang, Zhongyuan Fu, Shuxin Yang, Tingjian Wang, Liqin Wang, Liuhe Li〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The case-hardened 14Cr14Co13Mo4 martensitic stainless steel is carburized by low-pressure carburizing method. Plenty of second phase particles appear in the case layer. C concentration is measured by Carbon and Sulphur analyzer. Precipitation of second phase induces the improvement of C concentration in case layer. XRD results indicate that the second phase is composed of M〈sub〉23〈/sub〉C〈sub〉6〈/sub〉, M〈sub〉6〈/sub〉C, M〈sub〉7〈/sub〉C〈sub〉3〈/sub〉 and intermetallic χ phase. EBSD results show layering distribution of carbides varied with C concentration. Phase diagram of 14Cr14Co13Mo4 steel is calculated by Thermo-Calc software to explain the phase transformation during the carburizing. Low-pressure carburizing process is simulated by DICTRA software to explain C diffusion in 14Cr14Co13Mo4 steel. The simulated C concentration profile agrees well with the experimental measured carbon values, which means that low-pressure carburizing parameters can be optimized by this modeling method.〈/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): Biswajyoti Mukherjee, Aminul Islam, Krishna Kant Pandey, O.S. Asiq Rahman, Rishow Kumar, Anup Kumar Keshri〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Yttria stabilized Zirconia thermal barrier coatings with around 200 μm overlay of Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and CeO〈sub〉2〈/sub〉 were deposited on Inconel substrate using atmospheric plasma spray technique. Hot corrosion tests were carried out on the thermal barrier coating in molten salt mixtures (45 wt% Na〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 + 55 wt% V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉) at 1150 °C for 30 h. Although the YSZ and Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/YSZ coatings were gradually degraded by the infiltration of the molten salt, the CeO〈sub〉2〈/sub〉/YSZ coatings remarkably restrained the infiltration of the molten salt into the YSZ coating. For the YSZ coating without any overlay, the YSZ reacted with V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 to form YVO〈sub〉4〈/sub〉 during exposure to the molten salt, leading to the formation of a large amount of monoclinic phase of ZrO〈sub〉2〈/sub〉 due to the leaching of Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 from YSZ. For the Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/YSZ coating, the Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 overlay reduced the rigorous infiltration of the molten salt, which caused in lesser amount of leaching of Y〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 from YSZ. However, for the CeO〈sub〉2〈/sub〉/YSZ coatings, CeO〈sub〉2〈/sub〉 not only physically prevented the molten salt infiltration, but also completely reacted with V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 to form CeVO〈sub〉4〈/sub〉 and completely restrained the infiltration of the molten salt into the YSZ coating. Additionally, the Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/YSZ and CeO〈sub〉2〈/sub〉/YSZ showed 17% and 52% increase in thermal shock resistance respectively compared to YSZ coating.〈/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-S0257897218312581-ga1.jpg" width="380" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/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): Haijuan Mei, Quanshun Luo, Xueli Huang, Ji Cheng Ding, Teng Fei Zhang, Qimin Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The variations of microstructure, mechanical properties, and oxidation behavior of Mo-V-Cu-N coatings are directly correlated to the chemical compositions, which significantly affects their tribological behavior. The aim of this work was to characterize Mo-V-Cu-N coatings with different chemical compositions deposited by high power impulse magnetron sputtering (HIPIMS) using single Mo-V-Cu segmental target, and to investigate the correlations between the lubricative oxides formed on coating surfaces with the variation of tribological behavior at different temperatures. The oxidation of Mo-V-Cu-N coatings started at 400 °C with the lubrication oxides of Mo-O and Cu-Mo-O were formed, which led to the decrease in coefficients of friction and wear rates of the coatings. It was found that the rapid outward diffusion of Mo and Cu atoms took place preferentially at around the growth defects (e.g. microparticles and pores). The incorporation of V atoms into Mo-Cu-N coatings enhanced the oxidation resistance at temperatures below 400 °C. At 500 °C, all the fcc B1-MoN and VN phases disappeared due to the severe oxidation, and the V〈sub〉2〈/sub〉O〈sub〉5〈/sub〉 phase was first appeared. Even though a relatively low coefficient of friction was obtained at 500 °C, the wear resistance of Mo-V-Cu-N coatings was decreased due to the severe oxidation and loss of mechanical strength.〈/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): Sheida Shiri, Akindele Odeshi, Ning Chen, Renfei Feng, Ronny Sutarto, Qiaoqin Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tantalum (Ta) exists in body-centered cubic (α phase), tetragonal (β phase), and face-centered cubic (fcc) crystal structures. The β phase is a metastable structure formed in thin films and is often mixed with the α phase. The fcc phase has only previously been reported as dispersed fine grains embedded in α or β phase. In this study, Ta thin films were deposited on silicon substrates by magnetron sputtering. A mixture of α and β phases was observed in the films when the deposition temperature was lower than 400 °C. The β phase content decreased gradually with the increase in deposition temperature, and completely disappeared at 400 °C. It is interesting that when the deposition temperature reached 500 °C, both α and β phases disappeared, and Ta films became a fcc structure. The structure and the stabilization of the fcc Ta thin films were further investigated using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy, and the results are presented in the present paper. This new finding would open new research and application directions for Ta materials.〈/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): V. Dalbauer, S. Kolozsvári, J. Ramm, C.M. Koller, P.H. Mayrhofer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉The structural evolution of cathodic arc evaporated Al-Cr-O coatings with hugely different Al, Cr, and O contents was investigated by 〈em〉in-situ〈/em〉 XRD measurements upon annealing in oxygen up to 1200 °C. Different chemical compositions are achieved by arc evaporation of Al〈sub〉0.90〈/sub〉Cr〈sub〉0.10〈/sub〉, Al〈sub〉0.75〈/sub〉Cr〈sub〉0.25〈/sub〉, Al〈sub〉0.70〈/sub〉Cr〈sub〉0.30〈/sub〉, Al〈sub〉0.50〈/sub〉Cr〈sub〉0.50〈/sub〉, or Al〈sub〉0.25〈/sub〉Cr〈sub〉0.75〈/sub〉 cathodes and using either 20 standard cubic centimetres per minute (sccm) Ar, 50 sccm O〈sub〉2〈/sub〉, or 100 sccm O〈sub〉2〈/sub〉 per active source (p.a.s.). Generally, the crystallinity of the as-deposited coatings decreases with increasing O〈sub〉2〈/sub〉 flow rate during arc evaporation, while their Al/Cr ratio increases significantly (with respect to the cathode composition). The coatings prepared from Al-rich cathodes show first indications for the formation of corundum structured α-(Al,Cr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 phases at ~900 °C during annealing in O〈sub〉2〈/sub〉 atmosphere. Those, prepared from the Cr-rich cathode (Al〈sub〉0.25〈/sub〉Cr〈sub〉0.75〈/sub〉) with 20 sccm Ar or 50 sccm O〈sub〉2〈/sub〉 p.a.s., exhibit the formation of α-(Al,Cr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 phases already at 700–800 °C. Their corresponding coatings prepared with the highest oxygen flow rate of 100 sccm p.a.s., exhibit a considerable phase fraction of α-(Al,Cr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 already in the as-deposited state.〈/p〉 〈p〉Upon oxidation at 1200 °C, most coatings are basically composed of α-oxides, with a wide range of their Al/Cr-ratio. The coatings prepared with 100 sccm O〈sub〉2〈/sub〉 p.a.s., however, show the formation of α-(Al,Cr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 with a rather narrow Al/Cr-ratio, which is due to the sufficient mixing of Al, Cr, and O species already in the as-deposited state. Furthermore, selective oxidation (preference for Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) leads in most cases to the formation of Cr, which is detectable up to 1200 °C.〈/p〉 〈p〉Between 950 and 1050 °C, the formation of θ-(Al,Cr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 could be detected for cathodes with Al ≥ 50 at.% prepared with 20 sccm Ar or 50 sccm O〈sub〉2〈/sub〉 p.a.s. Coatings prepared with Al〈sub〉0.75〈/sub〉Cr〈sub〉0.25〈/sub〉, Al〈sub〉0.70〈/sub〉Cr〈sub〉0.30〈/sub〉, and Al〈sub〉0.50〈/sub〉Cr〈sub〉0.50〈/sub〉 cathodes and 100 sccm O〈sub〉2〈/sub〉 p.a.s. show the formation of θ-(Al,Cr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 already in the as-deposited state. α-(Al,Cr)〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 could only be detected for as-deposited coatings when preparing them with Al〈sub〉0.25〈/sub〉Cr〈sub〉0.75〈/sub〉 and 100 sccm O〈sub〉2〈/sub〉 p.a.s.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 85〈/p〉 〈p〉Author(s): Ye Yuan, Renliang Chen, Pan Li〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The coaxial rigid rotor helicopter has been proposed as a future high-performance rotorcraft concept. However, the aerodynamic interference of this helicopter is complicated because it couples with the unique flapping feature of the rigid rotor, which further alters the trim characteristics of coaxial rigid rotor helicopters. Thus, a multi-point vortex ring element (MVRE) model is developed to simulate the aerodynamic interference between rotors. The method for establishing this MVRE model is illustrated, and a wind tunnel experimental dataset is used to assess its precision hover and forward flight states. Next, a flight dynamics model of the coaxial rigid rotor helicopter is built based on the MVRE aerodynamic interference model and the flapping feature of the rigid rotor. The influence of the rotor wake on the fuselage and the horizontal and vertical tails can also be calculated using this model. The trim characteristics of this helicopter are evaluated with flight test data for speeds ranging from 0 m/s to 80 m/s, and the results confirm that this model can reflect the trim characteristics with satisfactory precision. In addition, the calculation process demonstrates that the MVRE model provides a much faster computing rate. Considering the aerodynamic interference and rigid rotor characteristics, the trim results of the coaxial rigid rotor helicopter present unique features: aerodynamic interference in the coaxial rotor system not only increases the collective pitch and the collective differential but also adds a negative gradient under the forward speed in the longitudinal cyclic pitch in the low-speed forward flight range. Moreover, the rotor wake effect on the other parts of the helicopter is distinct from the corresponding effects on conventional helicopters in terms of the trim characteristics.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): M. Rivier, J. Lachaud, P.M. Congedo〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Spacecrafts such as Stardust (NASA, 2006) are protected by an ablative Thermal Protection System (TPS) for their hypersonic atmospheric entry. A new generation of TPS material, called Phenolic Impregnated Carbon Ablator (PICA), has been introduced with the Stardust mission. This new generation of low density carbon-phenolic composites is now widely used in the aerospace industry. Complex heat and mass transfer phenomena coupled to phenolic pyrolysis and pyrolysis gas chemistry occur in the material during atmospheric entry. Computer programs, as the Porous material Analysis Toolbox based on OpenFoam (PATO) released open source by NASA, allow to study the material response. In this study, a non-intrusive Anchored Analysis of Variance (Anchored-ANOVA) method has been interfaced with PATO to perform low-cost sensitivity analysis on this problem featuring a large number of uncertain parameters. Then, a Polynomial-Chaos method has been employed in order to compute the statistics of some quantities of interest for the atmospheric entry of the Stardust capsule, by taking into account uncertainties on effective material properties and pyrolysis gas composition. This first study including pyrolysis gas composition uncertainties shows their key contribution to the variability of the quantities of interest.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Mingliang Suo, Baolong Zhu, Ruoming An, Huimin Sun, Shengzhong Xu, Zhenhua Yu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Data-driven fault diagnosis is more suitable than model-based methods for diagnosing the complicated spacecraft systems, e.g., the satellite power system, because of its simplicity and convenience. Nevertheless, some redundant and irrelevant features in monitoring data are usually not conducive to identify fault state but significantly reduce the correct rate of diagnosis and increase the computational complexity and memory storage space. The existing filter feature selection approaches usually need to provide the number of selected features in advance, which brings an extra burden to decision makers. To make up for this deficiency, this paper proposes a feature selection method based on fuzzy Bayes risk (FBR) to generate an optimal feature subset automatically without having to preset the feature number. A heuristic forward greedy feature selection algorithm based on the proposed fuzzy Bayes risk theory is designed. Subsequently, a data-driven fault diagnosis strategy is designed by employing FBR and Support Vector Machine (SVM). Finally, numerical experiments on UCI data and the fault diagnoses of satellite power system are carried out to illustrate the superiority and applicability of the proposed method. The results of comparison experiments show that both classification accuracy of UCI data and diagnosis effect of satellite power system are better than the other state-of-the-art methods.〈/p〉〈/div〉

Description: 〈p〉Publication date: January 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 84〈/p〉 〈p〉Author(s): Daolun Liang, Rui Xiao, Jianzhong Liu, Yang Wang〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Adding other metals is an efficient method of breaking through the energy release efficiency limitation of boron-based fuels. A laser ignition testing system was used for investigating the ignition and heterogeneous combustion characteristics of aluminum boride and boron–aluminum blend. The emission spectra and combustion flames of the samples during combustion were recorded by a fiber optic spectrometer and a high-speed camera, respectively. The component, morphology, and distribution features of the condensed combustion products (CCPs) were then analyzed using an X-ray diffractometer, a scanning electron microscope, and an X-ray energy dispersive spectrometer. The emission spectral intensity curves show that the boron–aluminum blend has better ignition feature than aluminum boride (the ignition delay time was 45% shorter). However, the combustion intensity and self-sustaining combustion time of boron–aluminum blend are both inferior to those of aluminum boride. In full wave emission spectra of the samples, the characteristic peaks of combustion intermediate products like BO〈sub〉2〈/sub〉, AlO, and AlO〈sub〉2〈/sub〉 were found. The combustion flames of the two samples were both yellow green and tapered. The variation trend of the flame size corresponded to that of the emission spectral intensity curves. During the first half of the combustion, large amounts of sparks were ejected from the combustion flame of boron–aluminum blend, which caused the acute fluctuation of combustion intensity. B, Al, B〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉, AlN, and Al〈sub〉5〈/sub〉O〈sub〉6〈/sub〉N were detected in the CCPs of both samples. In addition, the CCPs of aluminum boride contained unburned AlB〈sub〉2〈/sub〉, and those of boron–aluminum blend contained Al〈sub〉4〈/sub〉B〈sub〉2〈/sub〉O〈sub〉9〈/sub〉. Webbed AlN fibers were observed only in the CCPs of boron–aluminum blend, while AlN and Al〈sub〉5〈/sub〉O〈sub〉6〈/sub〉N whiskers were found in those of both samples. The observed bulks were partially oxidized AlB〈sub〉2〈/sub〉 in the CCPs of aluminum boride, or partially oxidized B in those of boron–aluminum blend. As both diffusion and melt-dispersion reactions of aluminum were proceeded during the combustion of boron–aluminum blend, oxidation products of aluminum with different morphology were found in the CCPs of boron–aluminum blend as follows: smooth aluminum spheres with low oxidation degree, rough aluminum oxide spheres with high oxidation degree, empty aluminum oxide shells with hollows or cracks, and fine aluminum oxide particles adhered on the surface of boron bulks.〈/p〉〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 85〈/p〉 〈p〉Author(s): Xiaolin Ai, Linlin Wang, Jianqiao Yu, Yuanchuan Shen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study considers the cooperative guidance problem for multiple missiles against a stationary target with the field-of-view constraint. A two-stage guidance scheme is proposed to realize salvo attack of multiple missiles without using any information on time-to-go or its estimation. In the first guidance phase, this study integrates the cooperative guidance problem, state tracking problem and field-of-view constraint into a unified optimal control framework. A non-quadratic field-of-view constraint cost is innovatively constructed via an inverse optimal control approach, which leads to an analytical, distributed, and optimal guidance law to provide favored initial conditions for the latter phase. The stability and optimality of the closed-loop system is also proven. With respect to the second guidance phase, missiles disconnect from each other and are governed by the typical pure proportional navigation guidance law to eventually realize the salvo attack mission. Numerical simulations are performed to validate the theoretical results.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Hui Sun, Sheng-Chi Chen, Chung-Hsien Wang, Yu-Wei Lin, Chao-Kuang Wen, Tung-Han Chuang, Xin Wang, Song-Sheng Lin, Ming-Jiang Dai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, (Al, Co)-ZnO films were co-sputtered on glass substrate through radio frequency sputtering at 100 °C. The film's structure, electrical and magnetic properties as a function of Al doping content is investigated. The results indicate that (Al, Co)-ZnO films crystallinity can be suppressed by Co doping or (Co, Al) co-doping. With the substitution of Zn〈sup〉2+〈/sup〉 by Al〈sup〉3+〈/sup〉, the film's conductivity improves. All the films present ferromagnetic behavior at room temperature. Upon increasing the Al doping amount, the film's saturation magnetization expresses a carrier-concentration dependent behavior. Three different regions can be defined, where BMP model and carrier-mediated exchange mechanisms play a role in the various regions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Naixiu Hu, Yijia Wang, Jiaxin Li, Qiuping Wei, Yunlu Jiang, Li Ma, Zhiming Yu, Kechao Zhou, Hangyu Long〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉To enhance the field emission performance and understand the emission essence of carbon materials, carbon films with different morphology and phase composition were fabricated by regulating the reactive gas flow ratio in a hot filament chemical vapor deposition system with the assistance of electric field and magnetic field. The characterization of carbon film quality and measurement of their field emission performance indicated that carbon nanostructures, including nanoclusters, nanopillars and nanotips, which were determined by the methane concentration in the process, were formed under the assistance of electric field. Further magnetic field assistance could lead to the formation of finer nanostructures with higher crystallinity. Field emission performance was highly dependent on the morphology and phase composition of the carbon films. Among all the samples, carbon nanotips, deposited in high methane concentration with the co-assistance of magnetic and electric field, possessed the best field emission performance, with the lowest turn-on field of 6.5 V·μm〈sup〉−1〈/sup〉 (J = 10 μA·cm〈sup〉−2〈/sup〉). Besides, a comparative study on the fitting degree of several conduction mechanisms revealed that the essence of field emission was the combination of several emission mechanisms, which was also dependent on the morphology and phase composition of these 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-S0257897218313604-ga1.jpg" width="487" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Julien Keraudy, Rommel Paulo B. Viloan, Michael A. Raadu, Nils Brenning, Daniel Lundin, Ulf Helmersson〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The effects of a positive pulse following a high-power impulse magnetron sputtering (HiPIMS) pulse are studied using energy-resolved mass spectrometry. This includes exploring the influence of a 200 μs long positive voltage pulse (〈em〉U〈/em〉〈sub〉rev〈/sub〉 = 10–150 V) following a typical HiPIMS pulse on the ion-energy distribution function (IEDF) of the various ions. We find that a portion of the Ti〈sup〉+〈/sup〉 flux is affected and gains an energy which corresponds to the acceleration over the full potential 〈em〉U〈/em〉〈sub〉rev〈/sub〉. The Ar〈sup〉+〈/sup〉 IEDF on the other hand illustrates that a large fraction of the accelerated Ar〈sup〉+〈/sup〉, gain energies corresponding to only a portion of 〈em〉U〈/em〉〈sub〉rev〈/sub〉. The Ti〈sup〉+〈/sup〉 IEDFs are consistent with the assumption that practically all the Ti〈sup〉+〈/sup〉, that are accelerated during the reverse pulse, originates from a region adjacent to the target, in which the potential is uniformly increased with the applied potential 〈em〉U〈/em〉〈sub〉rev〈/sub〉, while much of the Ar〈sup〉+〈/sup〉 originates from a region further away from the target over which the potential drops from 〈em〉U〈/em〉〈sub〉rev〈/sub〉 to a lower potential consistent with the plasma potential achieved without the application of 〈em〉U〈/em〉〈sub〉rev〈/sub〉. The deposition rate is only slightly affected and decreases with 〈em〉U〈/em〉〈sub〉rev〈/sub〉, reaching ~90% at 〈em〉U〈/em〉〈sub〉rev〈/sub〉 = 150 V. Both the Ti〈sup〉+〈/sup〉 IEDF and the small deposition rate change indicate that the potential increase in the region close to the target is uniform and essentially free of electric fields, with the consequence that the motion of ions inside the region is not much influenced by the application of 〈em〉U〈/em〉〈sub〉rev〈/sub〉. In this situation, Ti〈sup〉+〈/sup〉 will flow towards the outer boundary of the target-adjacent region, with the momentum gained during the HiPIMS discharge pulse, independently of whether the positive pulse is applied or not. The metal ions that cross the boundary in the direction towards the substrate, and do this during the positive pulse, all gain an energy corresponding to the full positive applied potential 〈em〉U〈/em〉〈sub〉rev〈/sub〉.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Wen Xi, Wenqiang Ding, Shengwang Yu, Naiming Lin, Tianxu Meng, Qi Guo, Xiaozhen Liu, Xiaoping Liu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In order to obtain the combination of improved abrasion and corrosion resistances, TaC/Ta composite coatings were made on C17200 beryllium copper alloy by two steps, surface Ta-alloying at 800 °C for 2 h followed by carburizing at 670 °C for 0.5 h. The corrosion property of TaC/Ta coatings in H〈sub〉2〈/sub〉SO〈sub〉4〈/sub〉 solution (10%) was investigated by polarization curves and electrochemical impedance spectroscopy. The microstructure of the composite coatings and corroded surface were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscope equipped with energy dispersive spectrometer, respectively. The results showed that the composite coating, 8.79 μm in thickness, was composed of the TaC top layer and Ta-Cu intermediate layer. The untreated bare C17200 alloy substrate revealed a poor corrosion resistance. After Ta-alloying and carburizing, the corrosion resistance of C17200 alloy increased due to a higher self-corrosion potential and lower self-corrosion current of TaC/Ta coatings. In addition, TaC/Ta coatings had wider frequency scope, larger radius of capacitive semi-circles, phase angle and |Z| value compared with bare alloy. The protection efficiency of TaC/Ta coatings calculated from electrochemical impedence and potentiodynamic polarization was over 90%. The dense corroded surface and Ta oxide formed in the corroded surface caused an improved anti-corrosion property of TaC/Ta coatings.〈/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-S0257897218313963-ga1.jpg" width="389" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Gui-hong Song, Qian-Nan Liu, Hao Du, Fang Hu, Chao Wang, Chun-lin He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Mg〈sub〉2〈/sub〉(Si,Sn) solid solutions films have been deposited on single crystalline Si(111) substrates under temperatures from 130 to 400 °C by magnetron sputtering using a Mg-Si-Sn alloy target. The phase components, microstructures and the thermoelectric properties of these films were investigated. It is indicated that the films deposited under lower temperature (≤300 °C) possess a cubic anti-fluorite structure phase and their structures transform into orthorhombic and hexagonal with the increasing temperature to 400 °C. Meanwhile, the tetragonal structure metal Sn phase occurs on samples deposited under temperatures of 350 °C and 400 °C. Furthermore, the film deposited under 350 °C is composed of cubic anti-fluorite structure and orthorhombic structure phase, and possesses the highest absolute value of Seebeck coefficient and the highest electrical resistivity. On the other hand, the film deposited under 130 °C which is composed of only cubic anti-fluorite structure possesses the highest power factor at all measured temperature due to higher absolute value of Seebeck coefficient and lower electrical resistivity. It is suggested that the Mg〈sub〉2〈/sub〉(Si,Sn) solid solutions film with cubic phase structure has higher power factor than that with orthorhombic and hexagonal phase structure.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 23 December 2018〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology〈/p〉 〈p〉Author(s): Kui Wen, Xuezhang Liu, Kesong Zhou, Min Liu, Huichao Zhu, Jian Huang, Zhongcheng Zhang, Renzhong Huang, Jie Mao, Xingchen Yan, Hanlin Liao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The coating quality and reproducibility of plasma spraying are significantly affected by the characteristic of plasma jet that is closely related to the arc root attachment. In this study, a 3D time-dependent numerical model based on the Local Thermodynamic Equilibrium (LTE) assumption was developed to investigate the arc dynamics and its effect on the distributions of temperature and flow field both inside and outside of the torch. The results show that there is the coexistence of multiple arc roots, and the particular attachment location of plasma arc leads to a significant asymmetry in distributions of temperature, velocity as well as electric potential and field strength. The continuous movement of the plasma arc not only caused the fluctuations of the arc voltage drop, but also resulted in the temporal variations of the plasma temperature and velocity. Moreover, the predicted temperature and velocity distributions of plasma jet were in good agreement with experimental measurements.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Fa Chang, Bingjie Cai, Chong Zhang, Biao Huang, Shuai Li, Pinqiang Dai〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The FeCr〈sub〉x〈/sub〉CoNiB (x values in molar ration, x = 0.5–3) high-entropy alloys coatings were prepared by laser cladding on an AISI 1045 steel substrate. Annealing and high temperature oxidation experiments were performed on the FeCr〈sub〉x〈/sub〉CoNiB (x = 0.5–3) coatings at 900 °C. The phase structure, morphology, and composition of the coatings and oxidation layers were analyzed by XRD, TEM, SEM, and EDS. Results demonstrated that the FeCr〈sub〉x〈/sub〉CoNiB coatings are composed of simple face-centred cubic (FCC) phase and boride. The hardness value of the coatings is significantly improved due to the boride, which is achieved 860 HV at x = 0.5. Cr is conducive to inhibiting the coarsening of boride and enhancing the resistance of coatings to high-temperature softening. The oxidation kinetics curve of FeCr〈sub〉x〈/sub〉CoNiB coatings basically follows oxidation dynamic the parabolic law. The selective oxidation in the FeCr〈sub〉x〈/sub〉CoNiB coatings changed from the oxidation of Fe to the oxidation of Cr as an increase in Cr content, and finally formed continuous Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 film. The high temperature oxidation resistance of the FeCr〈sub〉x〈/sub〉CoNiB coatings dropped with adding boron into the coatings, which improved contributing to Cr increasing. FeCr〈sub〉x〈/sub〉CoNiB coatings gain a better high temperature oxidation resistance as x ≥ 2 (33.3 at.%).〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Guo Peitao, Tang Mingyang, Zhang Chaoyang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ceramic coatings have been successfully fabricated on the surface of Magnesium alloys (AZ31D) by plasma electrolytic oxidation (PEO) in an alkaline silicate electrolyte with and without the addition of graphite. The influence of graphite on the surface morphology, microstructure, phase composition, chemical composition, corrosion resistance, and tribological behavior of ceramic coatings was scrutinized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), potentiodynamic polarization, MFT-4000 multifunctional material surface performance instrument. The ceramic coating with the addition of graphene exhibits better corrosion resistance and tribological performance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Ioana-Laura Velicu, Gabriela-Theodora Ianoş, Corneliu Porosnicu, Ilarion Mihăilă, Ion Burducea, Alin Velea, Daniel Cristea, Daniel Munteanu, Vasile Tiron〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Bipolar Pulse High Power Impulse Magnetron Sputtering (BP-HiPIMS) was investigated and used in this work to control the ion bombardment process of growing thin films and to improve their structure and properties. Energy-resolving mass spectroscopy was used to investigate the effect of reverse target voltage on the ion energies and fluxes during BP-HiPIMS of a high-purity copper target, in argon gas. It was found that the reverse target voltage provides a wide range of ion energies and fluxes incident to the growing film, which, in turn, produce a wide variety of effects during the deposition process, improving the adhesion strength and influencing both surface and bulk properties. Fast ICCD imaging was used to investigate both HiPIMS and BP-HiPIMS plasma dynamics. The temporal and spatial distributions of plasma potential measurements were performed in order to explain the mechanisms for accelerating the ions. The topological, structural and mechanical properties of the deposited coatings were investigated using atomic force microscopy (AFM), X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), thermal desorption spectroscopy (TDS), scanning electron microscopy (SEM), nanoindentation and scratch tests. The obtained results indicate an energy-enhanced deposition process during BP-HiPIMS, the deposited films being characterized by smooth surfaces, dense microstructure, small inert gas inclusions, high elastic strain to failure, scratch resistance and good adhesion to the substrate. These improvements in the films' structure and properties may be attributed to the intense and energetic ion bombardment taking place during the deposition process. During BP-HiPIMS operation, there is no net increase in the deposition rate as compared to the monopolar regime due to the re-sputtering process.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Jun Hu, Shijun He, Zhen Wang, Jianbo Zhu, Liping Wei, Zhong Chen〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 composite films with micro-nanostructure are prepared on the N80 steel surface by a two-step hydrothermal method, followed by heat treatment. The prepared dual-scale film, after the modification with stearic acid, shows superhydrophobic property with a water contact angle of 159.6° and sliding angle of 2.2°. The greatly decreased corrosion current density and the largely increased impedance indicate the superhydrophobic surface can protect steel sample well from corrosion. Furthermore, the superhydrophobic Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 composite film also showed excellent self-cleaning ability and was able to maintain its anti-wettability when immersed in water. Our work finds that the concentration of NaOH in the second hydrothermal method is a critical factor for the morphology of the Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 film and the annealing treatment plays a significant role in realizing the superhydrophobic stearic acid coated micro-nanostructure Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉/Fe〈sub〉3〈/sub〉O〈sub〉4〈/sub〉 composite.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): E.J.D.M. Pillaca, M.A. Ramírez, J.M. Gutierrez Bernal, D.C. Lugo, V.J. Trava-Airoldi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, the pulsed-DC PECVD deposition system was used to produce Diamond-like carbon (DLC) film on the internal surface of a long metal tube (200 cm in length and 10 cm in diameter) employed as the deposition chamber itself. Firstly, the features of plasma discharges and the temperature distribution along the tube external surface were studied using argon, silane, and acetylene. The experimental results demonstrate that a stable discharge can be established inside the tube. It was found that when the precursor gas is employed, a temperature gradient on the tube surface is formed. Secondly, PECVD experiments regarding DLC film deposition inside the inner surface of the tube are described. For this purpose, polished stainless steel and silicon wafer samples were mounted on the inside tube surface for subsequent analysis of the coatings. It was found that the growth rate and the structure properties of the DLC film varied along the axial direction of the tube. However, surfaces of DLC film with high sp〈sup〉3〈/sup〉 content provided better tribological characteristics. These results were mainly attributed to complex processes of local dissociation and activation happened by collision between the electrons and neutrals.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 85〈/p〉 〈p〉Author(s): Jichao Li, Juan Du, Fan Li, Qianfeng Zhang, Hongwu Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A hybrid slot–groove casing treatment (CT) composed of front axial slots and rear circumferential grooves is experimentally studied in a low-speed axial compressor in consideration of stability and efficiency. Results show that the hybrid slot–groove CT can improve the stall margin by 19.79% with an efficiency penalty of 1.5%. Compared to full-groove and full-slot CTs, the hybrid slot–groove CT's stall margin improvement and minimization of efficiency loss are excellent. Detailed measurements indicate that, unlike smooth casing (SC), the hybrid slot–groove CT can unload the blade tip, weaken the tip leakage vortex, and improve the disturbance observed downstream to postpone stall. Given the influence of serious passage blockage derived from the hub region after improving tip flow capability under the hybrid slot–groove CT, the stall route and inception captured in the casing wall and different downstream radial positions demonstrate that, unlike the SC with a typical spike-type inception (short length-scale with 2–3 blade passages), the hybrid slot–groove CT creates a long length-scale stall inception (6–8 blade passages). In addition, a new type of instability inception with a different frequency band from the stall cell is found in the hub region under the hybrid slot–groove CT. This inception appears more than hundreds of revolutions before the fast trigger of spike-type inception and can be used as an early stall warning signal under high hub loading.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 85〈/p〉 〈p〉Author(s): L. Prince Raj, J.W. Lee, R.S. Myong〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The impingement behavior of large water droplets, their interactions with the solid wall and the subsequent ice accretion and aerodynamic effects have become a key issue in in-flight aircraft icing. In this study, ice accretion and aerodynamic effects on a multi-element airfoil were investigated under the recently introduced Appendix O icing envelope. Supercooled large droplet (SLD) dynamics were taken into account by employing a unified computational approach. Ice accretion was simulated using a partial differential equation (PDE) based solver, instead of the commonly used control volume method. The numerical solver of the SLD impingement was built on the droplet deformation and droplet–wall interaction splash models. The unified solvers for clean air, large droplet impingement, ice accretion, and the aerodynamic analysis of ice effects—all of which are based on a single unstructured upwind finite volume framework—were first validated using available experimental data and then applied to investigate ice accretion and the resulting aerodynamic effects on multi-element airfoils for various flight conditions and, in particular, near-freezing SLD icing conditions. Interestingly, two counter-intuitive results were found when comparing the ice accretion and associated aerodynamic degradation for non-SLD and SLD cases. Moreover, considering runback ice was shown to be essential in the design of an ice protection system (IPS) for the multi-element wing.〈/p〉〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 85〈/p〉 〈p〉Author(s): Ryszard Szwaba, Piotr Kaczynski, Piotr Doerffer〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The main objective of this research is to study experimentally the effect of transition on the flow structure of the shock wave boundary layer interaction in the blades passage of a compressor cascade. For this purpose a model of a turbine compressor passage was designed and assembled in a transonic wind tunnel. In the experiment the distributed roughness with different heights and locations was used to induce transition upstream of the shock wave. Three locations of distributed roughness in form of standard sandpaper strips were chosen to apply on the blade. The average roughness height comprised in a range of 8 to 16 μm. All together 8 different flow cases were investigated. The paper focuses on the influence of the boundary layer transition induced by different roughness values and locations on the flow pattern in the blades passage of a compressor cascade. Very promising results were obtained in the roughness application for the boundary layer transition control, demonstrating a positive effect in changing the nature of the interaction.〈/p〉〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 85〈/p〉 〈p〉Author(s): Yongmeng Liu, Maowei Zhang, Chuanzhi Sun, Ming Hu, Danyang Chen, Zewei Liu, Jiubin Tan〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The paper proposes a method to minimize stage-by-stage initial unbalance in the aero engine assembly of multistage rotors based on the connective assembly model. The process of the mass eccentric deviation propagation in the assembly is analyzed. The initial unbalance of the final assembly is improved by properly selecting the assembly orientations of multistage rotors. A constrained nonlinear programming model is extracted from the optimal assembly strategy by choosing the initial unbalance as the objective function, and choosing the assembly orientations as the nonlinear constraint. The globally optimized solution of the constrained nonlinear programming model is solved using a genetic algorithm. The proposed method is used on an experimental set-up with the horizontal balancing machine and the effectiveness of the proposed method is verified by the assembly of the multistage rotors using the optimal assembly strategy. Compared to the direct assembly strategy, which the assembly orientations without consideration, the initial unbalance of final assembly using the optimal assembly strategy are reduced by 45.8%, 63.1% and 72.7% for two, three and four rotors assembly, respectively. The proposed method can improve the assembly quality of multistage rotors in the aero engine assembly and be used for assembly guidance, tolerance allocation, and so on, especially for the assembly with a large number of rotors.〈/p〉〈/div〉

Description: 〈p〉Publication date: February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Aerospace Science and Technology, Volume 85〈/p〉 〈p〉Author(s): Jicheng Ma, Juntao Chang, Junlong Zhang, Wen Bao, Daren Yu〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A control-oriented unsteady 1-D model for regeneratively-cooled scramjet engine which is composed of flow-combustion module, regenerative cooling module, is presented in this paper. It can reflect unsteady process in real-world where flow-combustion module couples with regenerative cooling module at each time step. The coupled 1-D model is quantitatively validated under steady and unsteady conditions. By the analyses of steady characteristics using this coupled 1-D model, it can be concluded that the allowable maximum first stage fuel equivalence ratio of regeneratively-cooled scramjet engine is lower and thrust is larger than no-cooled scramjet engine for the same equivalence ratio under the same flight Mach number. The difference of overtemperature boundary between regeneratively-cooled and no-cooled scramjet engine is also pointed. Moreover, regenerative cooling process results in moving toward less of fuel equivalence ratio of combustion mode transition. Unsteady characteristics analyses are investigated subsequently. Results indicate that there exists thermal inertia after kerosene flowing in cooling channels so that the flow rate of kerosene of entering into combustor cannot reflect kerosene changing signal in time. It leads to that thrust response time of regeneratively-cooled scramjet engine is longer than that of no-cooled scramjet engine. Some special attentions should be paid that combustion mode transition can be induced and affected by regenerative cooling process in some conditions. As a whole, the low computation cost makes this coupled 1-D model suitable for control system design and overall performance evaluation for regeneratively-cooled scramjet engine.〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Jiwang Zhang, Xing Li, Bing Yang, Huaqiang Wang, Jinxin Zhang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this study, the precipitate strengthened Cu-Ni-Si alloy was micro-shot peened by ceramic balls with a diameter of 40 μm. The fatigue tests using the peened specimens were conducted in air and in salt atmosphere respectively. The results show that a fine and hardening layer is formed on the surface of peened specimen and the compressive residual stress is introduced. There is no fatigue limit for specimens in both test conditions. The S-N curve of specimens in salt atmosphere shows a continuous decrease with the increasing number of loading cycles, while that in air shows a step-wise shape. Compared with the un-peened specimens, the fatigue strengths of specimens at 10〈sup〉7〈/sup〉 cycles are increased by 47% and 67% in air and in salt atmosphere respectively. The peened specimens in air condition failed from subsurface zone in high cycle fatigue region, while all the other specimens failed from surface. The micro-shot peening can improve the surface property and delay the crack initiation and propagation, so as to enhance the fatigue strength greatly.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Neha Verma, Giridharan Krishnamurthy, Frans D. Tichelaar, Amarante J. Böttger〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In this work, the effect of the deposition parameters of a magnetron sputtered Ti adhesive intermediate layer on the morphology and hydrogen absorption properties of thin Pd films of about 100 nm was investigated. The insertion of an adhesive layer between a Pd film and a rigid substrate usually suppresses or reduces hydrogen absorption. In this study, it is shown that by tuning the surface topography of the intermediate layer the morphology, crystallographic texture and hydrogen absorption properties of the Pd film can be controlled. The surface topography of the Ti layer was characterized using atomic force microscopy. The surface topography strongly depends on the Ti deposition conditions and can vary from widely spread large islands to densely packed small-grained islands depending on thickness (between 1 and 6 nm) and sputter pressure (0.4 and 3 Pa). TEM and XRD analysis led to the conclusion that rough Ti intermediate layers result in Pd films with an open columnar structure with small voids, and a weak and broad (111) texture. Smooth Ti intermediate layers promote the formation of Pd films with a dense columnar structure with fewer voids, and a strong and sharp (111) texture. Changes in the Pd adatom surface diffusion and shadowing effects are the main cause of the observed differences. Pd films with an open columnar morphology and weaker texture show better hydrogen absorption properties with respect to absorption capacity and kinetics of the films with dense columnar morphology. By tuning the surface topography of the Ti adhesive layer, Pd films with controlled morphology and texture can be prepared such that no delamination from the substrate occurs without compromising on absorption properties.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): N. Abu-warda, A.J. López, M.D. López, M.V. Utrilla〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉High velocity oxy-fuel (HVOF) technique was used to deposit an Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉-30(Ni20Al) coating on AISI 304 stainless steel substrate to improve its corrosion and wear performance at high temperature. First, thermal cycling tests at 750 and 850 °C were conducted in air atmosphere on both coated and uncoated stainless steel substrates to study the effectiveness of coating protection system at different exposure times (2, 6, 10 and 15 days). Then, high temperature corrosion and wear mechanisms were studied by SEM and XRD techniques. These analyses revealed that uncoated specimens were severely corroded but no oxidation on the coated substrates was detected. Oxide growth on the uncoated substrate was mainly formed by spinel (MnCr〈sub〉2〈/sub〉O〈sub〉4〈/sub〉 and FeCr〈sub〉2〈/sub〉O〈sub〉4〈/sub〉) and corundum (Fe〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and Cr〈sub〉2〈/sub〉O〈sub〉3〈/sub〉) type oxides. Meanwhile, these oxides were not found on the coated substrate. Wear rate of the coated specimen was found to be reduced from 6.9·10〈sup〉−4〈/sup〉 to 8.3·10〈sup〉−5〈/sup〉 mm〈sup〉3〈/sup〉/N·m compared to that of the uncoated specimen. The exposure to high temperatures improved coating wear resistance: wear rate was four times lower in the coated sample exposed to high temperatures compared to that of the non-exposed coated sample due to the formation of a harder phase of NiO.〈/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-S0257897218313598-ga1.jpg" width="324" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/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): Muhammad Atiq Ur Rehman, Muhammad Azeem Munawar, Dirk W. Schubert, Aldo R. Boccaccini〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Electrophoretic deposition (EPD) of composite coatings based on chitosan, gelatin and copper doped bioactive glass (Cu-BG) particles on 316L stainless substrates (SS) was investigated. Despite the fact that EPD offers easy control over the thickness and morphology of the produced coatings, the optimization of the EPD process is a tedious task due to the fact that a high number of variables (applied voltage, deposition time, distance between the electrodes, concentration of the suspension and pH of the suspension) is involved. Therefore, we used the Taguchi Design of Experiments (DoE) approach for accurate and economical process (reduced number of experiments) optimization. The suspension composition (chitosan, gelatin and Cu-BG ratio) and electric field related parameters (voltage and time) were optimized by L〈sub〉25〈/sub〉 type Taguchi array. The best coatings were obtained at the applied voltage of 30 V, deposition time of 5 min and the concentration ratio between chitosan/gelatin was 50:50 (vol%). Scanning electron microscopy (SEM) images revealed that Cu-BG particles were fairly homogenously dispersed in the chitosan/gelatin matrix. Fourier transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy confirmed the presence of chitosan, gelatin and Cu-BG particles (qualitatively). The tape test (ASTM D3359-97 and B571-97) elucidated the appropriate adhesion strength of coatings (obtained by EPD using optimized parameters) for orthopedic applications. Moreover, chitosan/gelatin/Cu-BG coatings exhibited suitable hydrophilicity.〈/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-S0257897218313252-ga1.jpg" width="403" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 February 2019〈/p〉 〈p〉〈b〉Source:〈/b〉 Surface and Coatings Technology, Volume 359〈/p〉 〈p〉Author(s): Huanli Liu, Xinggang Hou, Tingting Sun, Jianghong Yao, Ping Wu, Dejun Li, Jing Li, Jing Han〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The N〈sup〉+〈/sup〉 ions doped TiO〈sub〉2〈/sub〉 nanotubes (TNTs) were prepared by the methods of ion implantation and anodization. Phase and chemical composition, surface morphology and water contact angle of the samples were examined. The corrosion behavior of the samples in simulated body fluids was estimated by electrochemical impedance spectroscopy and polarization resistance measurements. L-929 fibroblast cells were used to identify the cytotoxic response of N〈sup〉+〈/sup〉 ions implanted TNTs. The density of the viable cells was determined by MTT assay. The antibacterial activities of N〈sup〉+〈/sup〉 ions implanted TNTs were studied by sterilization of 〈em〉E〈/em〉. 〈em〉coli〈/em〉 in the dark. Compared to TNTs, N〈sup〉+〈/sup〉 ions implanted TNTs exhibited more regular surface, and the corrosion resistance of N〈sup〉+〈/sup〉 ions implanted TNTs was improved. The N〈sup〉+〈/sup〉 ions implanted TNTs possessed better hydrophilicity. The water contact angle of implanted samples was decreased with the increase of implanted dose. In vitro cell culture experiments, it identified that the N〈sup〉+〈/sup〉 ions implanted TNTs were more favorable for cell attachment and proliferation. All the implanted samples showed antibacterial activity in the dark. The amounts of 〈em〉E〈/em〉. 〈em〉coli〈/em〉 on the implanted sample with 5 × 10〈sup〉17〈/sup〉 ions/cm〈sup〉2〈/sup〉 reduced by about 63.1% after 24 h compared to control sample.〈/p〉〈/div〉 〈/div〉