ALBERT

Notes: Purpose - To cover the main contributions and developments in solar thermal collectors through focusing on materials, heat transfer characteristics and manufacturing challenges. Design/methodology/approach - A range of published papers and internet research including research work on various solar thermal collectors (flat plate, evacuated tubes, and heat pipe tube) were used. Evaluation of solar collectors performance is critiqued to aid solar technologies make the transition into a specific dominant solar collector. The sources are sorted into sections: finding an academic job, general advice, teaching, research and publishing, tenure and organizations. Findings - Provides information about types of solar thermal collectors, indicating what can be added by using evacuated tube collectors instead of flat plate collectors and what can be added by using heat pipe collectors instead of evacuated tubes. Research limitations/implications - Focusing only on three types of solar thermal collectors (flat plate, evacuated tubes, and heat pipe tube). Practical implications - Useful source of information for consultancy and impartial advice for graduate students planning to do research in solar thermal technologies. Originality/value - This paper fulfils identified information about materials and heat transfer properties of materials and manufacturing challenges of these three solar thermal collectors.

Notes: Purpose - Copper and its alloys are widely used in industries because of their good resistance to corrosion and are often used in cooling water systems. Brass has been widely used for shipboard condensers, power plant condensers and petrochemical heat exchangers. Brass is susceptible to the corrosion process known as dezincification by means of which brass looses its valuable physical and mechanical properties leading to failure of structure. The aim of this investigation was to control the dezincification of brass in 3 per cent NaCl solution using benzotriazole (BTA) derivatives. Design/methodology/approach - BTA derivatives namely 1-hydroxymethylbenzotriazole (HBTA) and N,N-dibenzotriazol-l-ylmethylamine(ABTA) were synthesised and their inhibition behaviour on brass in 3 per cent NaCl solution was investigated by the weight-loss method, potentiodynamic polarisation, electrochemical impedance and solution analysis techniques. The morphology of the brass after corrosion in the presence and absence of the BTA derivatives was examined using scanning electron microscopy (SEM). Findings - Potentiodynamic polarisation studies showed that the BTA derivatives investigated were mixed type inhibitors, inhibiting the corrosion of brass by blocking the active sites of the brass surface. Changes in the impedance parameters (charge transfer resistance and double layer capacitance) were related to the adsorption of BTA derivatives on the brass surface, leading to the formation of a protective film. Solution analysis revealed that the BTA derivatives excellently controlled the corrosion of brass. SEM micrographs showed the formation of compact surface film on the brass surface in the presence of inhibitors, thereby providing better corrosion inhibition. Originality/value - Contributes to research on corrosion protection for copper and its alloys.

Notes: Purpose - To study flow-induced corrosion mechanisms for carbon steel in high velocity flowing seawater and explain corrosive phenomena. Design/methodology/approach - An overall mathematical model for flow-induced corrosion of carbon steel in high velocity flow seawater was established in rotating disk apparatus using both numerical simulation and test methods. By studying the impact of turbulent flow using the kinetic energy of turbulent approach and the effects of the computational near-wall hydrodynamic parameters on corrosion rates, corrosion behaviour and mechanism are discussed here. It is applicable to deeply understand the synergistic effect mechanism of flow-induced corrosion. Findings - It is scientific and reasonable to investigate carbon steel corrosion through correlation of the near-wall hydrodynamic parameters, which can accurately describe the influence of fluid flow on corrosion. The computational corrosion rates obtained by this model are in agreement with measured corrosion data. It is shown that serious flow-induced corrosion is caused by the synergistic effect between corrosion electrochemical factor and hydrodynamic factor. While corrosion electrochemical factor plays a dominant role in flow-induced corrosion. Originality/value - The corrosion kinetics and mechanism of metals in high velocity flowing medium is discussed in this paper. These results will help someone who is interested in flow-induced corrosion to understand in depth the type of issue.

Notes: Purpose - To investigate the influence of an organic corrosion inhibitor on the enhanced dissolution of metal, initiated by AFM tip scratching in corrosive media. Design/methodology/approach - The test solutions were 1.5?M NaCl and 0.01?M HCl. AFM tip scratching experiments were performed for Cu-Ni alloys in solutions with or without 0.005?M dodecylamine. AFM frictional loop tests were also performed to investigate the effect of dodecylamine on the tip-surface frictional interaction. Findings - Enhanced dissolution of Cu-Ni alloy was observed as a result of AFM tip scratching both in NaCl and HCl solutions, and in HCl the effect was more severe than was the case in NaCl. Enhanced dissolution was inhibited markedly by adding 0.005?M dodecylamine to the corrosive media. The results of frictional loop tests indicated that frictional interaction between the tip and the alloy surface was diminished by the adsorption of dodecylamine on the sample surface. The weakening of tip-surface frictional interaction and the elevation of the ionization energy of metal atoms were responsible for the notable inhibition effect of dodecylamine on the accelerated dissolution. Originality/value - In this paper, the influence of an organic corrosion inhibitor on the corrosion of metal induced by outside forces was investigated. This was carried out initially by AFM scratching skill and the inhibition mechanism of dodecylamine on the enhanced dissolution of Cu-Ni alloy initiated by AFM tip scratching.

Notes: Purpose - This paper is concerned with the study of silica fume that arises in tonnage amounts during the manufacture of ferrosilicon alloys; this was done in order to maximize productivity and to create new market for industrial by-product and/or waste material. Design/methodology/approach - The structure and particle shape of silica fume were identified using X-ray diffraction and electron microscope, respectively. Standard methods were used for the identification of chemical analyses, solubility, hydrogen ion concentration, specific gravity, bulking value, oil absorption, chemical resistance and particle size. The characterized and evaluated silica fume was applied in several paint formulations. The physico-mechanical, chemical and corrosion protective properties of the paint films were measured according to standard methods. Findings - The silica fume under investigation was a fine lightweight fluffy amorphous powder. It has a grayish-white color that makes it suitable for use as a filler and extender pigment in a wide variety of different fields of application; its amorphous nature favors safe use from a standpoint of industrial hygiene. It can be used as an economic pigment that possesses suitable values of specific gravity, bulking value and oil absorption. It also is inert, neutral and of an excellent chemical resistance. The material can be used successfully as an extender pigment in different paint formulations; taking into consideration that alkyd resin based paints should not be used in alkaline environments or mixed with basic pigments, or the paint film will deteriorate. Silica fume particles in the pigment mixture may offer a suitable opportunity for the voids formed by the larger particles to be occupied by smaller ones to produce a condition of maximum packing. It can be successfully used with the flaky aluminum or stainless steel anticorrosive pigments to produce a highly efficient corrosion protective film. Originality/value - There is increasing environmental concern with regard to excessive volumes of solid waste hazards accumulation. Silica fume that arises - as a disposal material - in tonnage amounts during the manufacture of ferrosilicon alloys can find a new market in paint industry. It can be used successfully for anticorrosive paints to provide well backed paint films.

Notes: Purpose - Aims to study the behaviour of four polycrystalline carbon steels in basic pitting solutions. Design/methodology/approach - Electrochemical investigations were carried out on four steels: Fe.06C, Fe.18C, Fe.22C and Fe.43C. The analysis was made using an X-ray fluorescence apparatus. The performance indicator was the pitting potential, which was obtained through potentiodynamic sweeping. Emphasis was placed on the influence of the pH, chlorine concentration, phase proportions in the steel and the initial electrode surface state. Findings - The results showed that in a solution with a low chlorine concentration, the performance of the steels according to pitting corrosion resistance decreased with the increase in carbon content. By raising the chlorine concentration, the order of performance was inverted gradually, while at a high chlorine concentration, the behaviour of the steels tended to be similar. The interpretation of the results is based on the consideration of cathodic reactions on the level of the cementite phase and the difference in the local chemical properties of the solution. In neutral solutions, pitting potentials were shifted cathodically, but the main observations developed for basic solutions remained valid. Originality/value - Provides further research on pitting corrosion.

Notes: Purpose - The objective of the present work was to study the kinetics of copper cementation on Fe metal in an acetone-water medium and in a dioxane-water medium. Design/methodology/approach - The impact of solvent concentration on cementation rate was determined by measuring the rate of copper cementation from CuSO4 onto an iron plate in the absence and in the presence of acetone and dioxane solvents.The thermodynamic parameters ?H#, ?S# and ?G# of the cementation of CuSO4-organic solvents were calculated. Linear plots of ?H# versus ?S# were obtained. Findings - It was demonstrated that the rate of cementation decreased with increasing concentration of solvents and increasing temperature. The isokinetic temperature data indicate that the cementation reaction is controlled by the entropy of the system. Originality/value - The findings have important implications for the reclamation of toxic and valuable metals from industrial waste streams.

Notes: Purpose - Work reported in the present paper investigated the inhibiting properties of a number of N-heterocyclic amines in 0.1?mol/l HClO4. An attempt also was made to correlate some molecular parameters of these compounds with their corrosion inhibitor efficiency. Design/methodology/approach - The test series included piperidine (pip), 2-methylpiperidine (2mp), 3-methylpiperidine (3mp), cis-2,6-dimethylpiperidine (26dp), 3,5-dimethylpiperidine (35dp), 3-hydroxy piperidine (3hp), 4-hydroxypiperidine (4hp), 4-aminopiperidine (4ap), piperazine (pz), 2-methylpiperazine (2mpz) and cis-2,6-dimethylpiperazine (26dpz). The inhibiting effect was investigated in 0.1&?mol/L HClO4 by potentiodynamic polarization (DC) and electrochemical impedance spectroscopy (EIS). Findings - The results show that these compounds suppressed both cathodic and anodic processes of iron corrosion in 0.1?mol/l HClO4 by adsorption on the surface, which followed a Langmuir adsorption isotherm. Experimental observations indicated that basic piperidine and piperazine were better corrosion inhibitors than were their derivatives. The inhibition properties of N-heterocyclic amines were found to be related to the charge on the nitrogen atom and the sum of the net charge of the all six atoms from the cyclic ring. Originality/value - This paper provides useful information relative to corrosion inhibition efficiency of the group of N-heterocyclic amines. It is concerned with a theoretical explanation between electronic and structural characteristics of these compounds and their inhibitor efficiency.

Notes: Purpose - The evaluation of Schiff bases derived from o-, m- and p-aminophenols and salicylaldehyde as corrosion inhibitors of zinc in sulfuric acid and to study their action mechanism. Design/methodology/approach - The effect of various parameters on the behaviour of these inhibitors has been studied using the weight loss and polarization measurements. Findings - In general, the ortho isomer was highly effective as a corrosion inhibitor because it formed a chelate with a six-membered ring and moreover the ortho isomer possessed pronounced electromeric effect. These inhibitors obey the Langmuir adsorption isotherm. The almost constant performance with temperature in the case of ortho and para isomers in 0.5?M sulfuric acid suggested strong adsorption bonds. The thermodynamic parameters suggested that this strong interaction of the inhibitor molecules with the metal surface resulted in spontaneous adsorption. It may be concluded that a good inhibitor is characterised by a relatively greater decrease in free energy of adsorption, lower entropy of adsorption and higher heat of adsorption. Polarization data indicated that all these isomers were predominantly cathodic inhibitors. The conjoint effect of external cathodic current and these inhibitors was either synergistic or additive. Research limitations/implications - Even more powerful Schiff bases need to be synthesised and evaluated as corrosion inhibitors with a number of metals and alloys in diverse media, which may be effective at low concentrations. Originality/value - Very few inhibitors exhibit such excellent inhibitive effect on zinc in aggressive corrosive media. Rarely do we find such detailed studies.

Notes: Purpose - To demonstrate corrosion inhibition capabilities of new cyclic nitrones, containing hydrophobic substituents. Design/methodology/approach - A number of new cyclic nitrones were synthesized. Corrosion inhibition efficiencies of these organic inhibitors were determined by gravimetric and electrochemical methods, using carbon steel as the substrate metal and 1?M HCl at 60°C as the corrosive environment. Concentration of inhibitor was varied between 50 and 400?ppm. Findings - All compounds exhibited excellent corrosion efficiencies that ranged between 90.0 and 98.3 percent in 1?M HCl at 60°C. Tafel tests corroborated these results. Research limitations/implications - The inhibitors were tested in acidic medium. It is unknown how these inhibitors will function in the presence of other ions that are typically present in natural corrosive environment. Originality/value - All organic compounds presented in this work are new and this is the first time their corrosion inhibition characteristics have been evaluated.

Notes: Purpose - To study the effects of isomers of organic compounds such as phenylenediamine, toluidine and nitroaniline as inhibitors for the corrosion of carbon steel in sulfuric acid. Design/methodology/approach - Standard methods have been adopted in this study such as weight loss, polarization tests, impedance measurements and hydrogen permeation studies to find out the corrosion behavior of carbon steel in sulfuric acid with and without inhibitors. Findings - All the selected isomers inhibited the corrosion. The best performance was found in ortho-phenylenediamine when compared with other inhibitors under study. Originality/value - It clearly shows the effect of isomers of phenylenediamine, toluidine and nitroaniline. The method of study may be applicable to find out the performance of other isomers of organic compounds. As these isomers behave as good inhibitors in sulfuric acid, these may be tried as inhibitors in other acids. Hence, this study is useful to academics and researchers in the field of corrosion science and engineering.

Notes: Purpose - To evaluate the corrosion performance and nano-mechanical behaviour of a brass substrate covered by different thick SiO2 layers deposited by means of plasma enhanced chemical vapour deposition (PECVD) technique. Design/methodology/approach - The comparison between laboratory and "industrial" objects revealed a very good corrosion behaviour and good mechanical performance of both of them: in particular it was possible to modulate the surface treatment to solve various problems from the industrial point of view. Findings - It was possible to reduce the Cu migration into the SiO2 coating during the PECVD deposition at a negligible level and to control it by the deposition; further, the nano-indentation tests revealed the great utility of the coating annealing in obtaining a significant improvement of the mechanical properties of the coated objects. Research limitations/implications - Even if some industrial problems were solved (minimization of the presence of the coating defects and transparency of the coatings), some on the layer hardness (anti-wear behaviour of the industrial objects) has to be better investigated and possibly solved. Practical implications - The work reports a deposition process that is carried out industrially over a two year period. Originality/value - This research reports a PECVD process realized on industrial objects: the originality is in the reached corrosion and mechanical performances that made it possible to realize a satisfactory industrial deposition.

Notes: Purpose - To investigate the inhibitive effect of Congo red dye (CR) for aluminium corrosion in strong alkaline solutions and evaluate the synergistic effect of halide ions on the inhibition efficiency. Design/methodology/approach - Corrosion rates of aluminium test coupons were determined by gravimetric technique at 30 and 60°C. Inhibition efficiencies of the additives (0.01-5.0?mM CR and 5.0?mM CR+0.5?mM halides) were evaluated by comparing corrosion rates of the test coupons in 2?M KOH solution in the absence and presence of the additives. Findings - CR inhibited aluminium corrosion in 2?M KOH by physical adsorption of the dye molecules on the corroding metal surface. Maximum efficiency at 30 and 60°C was 31.72 and 19.32 per cent, respectively. Dye adsorption was enhanced in the presence of halides in the order KCl?〈?KBr?〈?KI, with KI increasing efficiency up to 48.63 and 41.70 per cent at 30 and 60°C, respectively. Research limitations/implications - Further studies to involve variation of dye and halide concentrations for CR+halide systems to determine the best combination for optimum inhibition synergism. Originality/value - This paper forms part of an extensive database on the inhibition characteristics of organic dyes for corrosion of different metals in various aggressive environments. This is to serve as a guide to possible applications in metal-surface anodizing and as additives in surface coatings for service in different environments.

Notes: Purpose - The present paper proposes a theoretical analysis of the stability characteristics of a Jeffcott rotor-hybrid bearing system. It is intended that on the basis of the numerical results drawn from this study, appropriate recess depth, land size, orifice location and speed parameter for stable operation can be determined for use in the bearing design process. Design/methodology/approach - A Jeffcott rotor supported by hybrid oil film bearings with dual-row recesses and orifice- compensated restrictors is studied. In order to facilitate the calculation of film dynamics, using the perturbation method, the Reynolds equation was linearized and subsequently solved using finite difference techniques, whilst the stability maps were determined by the Routh-Hurwitz method. Findings - The data reported here suggest that the stability characteristics of the Jeffcott rotor-bearing system could be improved by the use of shallow, dual-recessed hybrid bearings with orifice compensation. In addition to greater eccentricity ratios, smaller land-width ratios and greater shaft stiffness may also provide shallow-recessed bearings with better stability. In all cases, the stability provided by upstream orifice-sited bearings is better than that provided by center orifice-sited bearings, whilst high-speed parameters may also provide a greater stability threshold. Originality/value - This study proposes an extensive database as a critical requirement in the design of hybrid bearings, in order to ensure that a rotor bearing system is operating stably.

Notes: Purpose - The purpose of the present study is to provide the dynamic characteristics of long journal bearings lubricated with couple stress fluids. Design/methodology/approach - Based upon the micro-continuum theory generated by Stokes, the dynamic Reynolds-type equation governing the film pressure is derived to account for the couple stress effects resulting from the non-Newtonian behavior of complex fluids. By applying the linear stability theory to the non-linear equations of motion the journal rotor, the equilibrium positions and dynamic characteristics of the system are evaluated. Findings - As compared to the classical Newtonian model, the effects of couple stresses signify enhanced stiffness and damping coefficients (including KXX, KXY?, BXX and BXY) at moderate values of the steady eccentricity ratio. Totally, as the rotor center operates at an eccentricity ratio about ?s=0.71, long bearings lubricated with couple stress fluids under small disturbance results in a higher stability threshold speed than that of the Newtonian-lubricant case. Originality/value - These findings provide engineers useful information in designing journal-bearing systems.

Notes: Purpose - The aim of the research is to investigate the ceramic brake lining on the brake performance.Design/methodology/approach - The brake lining which has new formulation has been produced by using various additive materials. Various techniques have been used in the production of brake lining. These ceramic linings were subjected to friction and wear tests under different loads, and changes in the hardness and microstructures were examined.Findings - As a result of this study, the following findings are reported. A direct proportional was not found between hardness and wear resistance due to the complexity of composite structure. Kevlar fibers were homogeneously distributed in the matrix and therefore, very few microvoids were observed in the structure. Similarly, stone wool was well spread out the braking pad and hence decreased the microvoids' occurrence. Heat treatment supplied more homogeneous structure and hence, microstructural variations were minimised during the brake action. On the other hand, heat treatment decreased the hardness of glass fiber reinforced specimens and increased the density. Each specimen was affected from the environmental conditions. However, water affected all specimens more than the other environmental conditions, such as salty water, oil and braking liquid. With the increasing of temperature, the ingredients in the braking pad were affected other due to better diffusion. On the other hand, hardness of specimens increases and density decreases due to heat treatment and also specific wear ratio changes.Research limitations/implications - Limitations in the present research are as follows: two different pressures and eight different temperatures were used and brake linings were subjected to wear test, hardness tests, microstructures were examined.Practical implications - For future work, instead of buying expensive brake lining, new and cheaper ceramic linings are produced. By this process, economic benefit can be gained and also environmental protection can be succeeded in producing such asbestos free brake linings.Originality/value - This paper fulfills an identified information and offers practical help to the industrial firms working with brake lining and also to the academicians working on wear of materials.

Notes: Purpose - The aim of the research is to investigate the influence of ceramic coating on the wear performance of machine parts. Design/methodology/approach - Ductile cast iron parts were coated using ceramics. Three ceramics were used for this purpose. These coated parts were subjected to wear tests under a stable load. A pin-on-disc wear test apparatus was used. Findings - As a result of this study, the following findings are reported: According to ASTM G 99-90 pin-on-disc experiments, Cr2O3 was found to be best coating material with low wearing rate. Within row, Al2O3 and ZrO2 can be given. According to the previous work, motor parts for example piston ring, cylinder liner and engine valve can be coated with ceramic. In this study, it is observed that the figure of merit is increased in this study. Only wearing data is given in this research. The other results are also supporter of the results taken from the wearing experiments. As a result, due to the decrease in heat loss and coaling stability of part can provide good results. With these, by coating there is a decrease in oil reduction. Research limitations/implications - Coatings were limited with three ceramics, a stable load was used, and coated parts were subjected to wear test. Practical implications - For future work, instead of using other coating materials, Cr2O3 is used for the best coating material with low wearing rate. By this process, working life of the machine parts can be extended and a number of economical advantages may also be obtained. Originality/value - This paper fulfills identified information needs and offers practical help to the industrial firms working with ceramic coating and also to the academicians working on wear of materials.

Notes: Purpose - Improved fuel economy, lower emission and longer durability are the major developing trends of engine oils. Aims to describe further research on the friction coefficient of engine oils. Design/methodology/approach - The lubricating durability D was defined based on definition of three characteristic points Pd, PS, Pi and three key time lengths Td, Ts, Ti. Two kinds of engine oils, respectively, belonging to GF-2 and GF-3 categories, were selected as samples to compare their lubricating durability. Findings - Test results indicate the GF-3 oil has much better lubricating durability than GF-2 oil. With investigation of the topography and chemical composition changes of wear tracks along with the tribotests' time extending, the meanings of three characteristic points were discussed. Analysis indicates much better tribofilm, formed by the synergistic effect of Ca-containing detergent with MoDTC/ZDTP in GF-3 oil, is the major factor resulting in GF-3 oil's longer lubricating durability. Originality/value - Provides further research on lubricating durability, which is important for engine oil change and maintenance, as well as decreased cost and pollution to the environment, and improved energy conservation.

Notes: Purpose - PEEK is an abbreviation for polyetheretherketone, a high performance engineering semicrystalline thermoplastic. This material can operate at higher temperatures and has excellent friction and wear properties, which are optimised in the specially formulated tribological grade PEEK-CF30. The purpose of this work was to develop a thermo-mechanical model to predict the tribological behaviour of the composite PEEK-CF30/steel pair, in dry sliding, related to friction and wear with the pv factor, the temperature and the sliding distance, using multiple regression analysis (MRA). Design/methodology/approach - This paper presents a new thermo-mechanical model to predict the tribological behaviour of the composite PEEK-CF30/steel pair, in dry sliding, using MRA. A plan of experiments was performed on a pin-on-disc machine PLINT TE67HT®. Findings - The objective was to establish a thermo-mechanical model to predict the PEEK-CF30 behaviour related to friction and wear with the pv factor (product of apparent pressure of contact and sliding velocity), the temperature and the sliding distance. This model was obtained by multiple linear regression. Finally, confirmation tests were performed to make a comparison between the obtained results from the mentioned model and the experimental results. Originality/value - The novel element of this paper is the application of design experiments and MRA in tribological model behaviour in an advanced material - PEEK-CF 30.

Notes: Purpose - This paper compares and contrasts two approaches to the treatment of pipeline corrosion "risk" - the probabilistic approach and the more traditional, deterministic approach. The paper aims to discuss the merits and potential pitfalls of each approach. Design/methodology/approach - Provides an outline of each approach. The probabilistic approach to the assessment of pipeline corrosion risks deals with many of the uncertainties that are common to the data employed and those with regard to the predictive models that are used also. Rather than considering each input parameter as an average value the approach considers the inputs as a series of probability density functions, the collective use during the assessment of risk yields a risk profile that is quantified on the basis of uncertain data. This approach differs from the traditional deterministic assessment in that the output yields a curve that shows how the "risk" of failure increases with time. The pipeline operator simply chooses the level of risk that is acceptable and then devises a strategy to deal with those risks. The traditional (deterministic) approach merely segments the output risks as either "high", "medium" or "low"; a strategy for managing is devised based on the selection of an appropriate time interval to allow a reasonable prospect of detecting deterioration before the pipeline corrosion allowance is exceeded, or no longer complies with code. Applies both approaches to the case of a 16.1?km long, 14?in. main export line in the North Sea. Findings - The deterministic assessment yielded a worst-case failure probability of "medium" with a corresponding consequence of "high"; classifications that are clearly subjective. The probabilistic assessments quantified pipeline failure probabilities, although it is important to note that more effort was required when performing such an assessment. Using target probabilities for "high" and "normal" consequence pipeline segments, indications were that between 8.5 and 13 years was the time period for which the target (predicted) failure probabilities would be reached, again depending on how effective corrosion mitigation activities are in practice. Basing pipeline inspections in particular on the outputs from the deterministic assessment would therefore be conservative in this instance; but this may not necessarily always be so. That the probabilistic assessment indicates that inspections justifiably may be extended beyond that suggested by the deterministic assessment is a clear benefit, in that it affords the opportunity to defer expenditure on pipeline inspections to a later date, but it may be the case that the converse may be required. It may be argued therefore, that probabilistic assessment provides a superior basis for driving pipeline corrosion management activities given that the approach deals with the uncertainties in the basic input data. Originality/value - A probabilistic assessment approach that effectively mirrors pipeline operations, provides a superior basis upon which to manage risk and would therefore likely maximize both safety and business performance.

Notes: Purpose - This paper describes new experimental evidence of the electropolymerization of furfural on non-noble metals such as low-carbon steel. The organic compound (2-furancarboxaldehyde) was selected because it is easily obtained from biomass and other sources. These results confirm the possibility of synthesizing a polymeric film, with good adherence and stability that provides a new protective barrier against corrosion to this kind of metal. Design/methodology/approach - Electrochemical methods such as chronoamperometry, chronopotentiometry and cyclic voltammetry (CV) were used to synthesize and characterize the polymer formed on the electrode surface. Some electrochemical impedance experiments were conducted in order to confirm the electrochemical behavior modification of the electrode, due to the presence of the organic film on the surface. Findings - The polymer film could be grown galvanostatically, potentiostatically or, during CV. The corrosion protection afforded by polyfurfural (PFy) that had been formed on a low-carbon steel surface was confirmed by the CV, EIS and polarization curves. Research limitations/implications - The possible synthesis of a new polymeric structure on a non-noble metal is interesting from a practical point of view. However, more experiments are necessary in order to test other organic solvents and other non-noble metals such as zinc, aluminium, copper, etc. Practical implications - The corrosion protection afforded by PFy that had been formed on a low-carbon steel surface was confirmed by the CV, EIS and polarization curves. Anodic current values associated with metal oxidation decreased when the metal surface was covered with the organic film. Originality/value - This is the first paper that deals with the electropolymerization of furfural on this type of metal. It was not found in the literature evidences that this polymer was synthesized before.

Notes: Purpose - To evaluate the inhibition efficiency (IE) of polyvinyl alcohol (PVA) in controlling the corrosion of carbon steel immersed in neutral aqueous solutions containing 60?ppm of Cl-, in the absence and presence of Zn2+. To investigate the influence of sodium sulphite (Na2SO3), sodium dodecyl sulphate (SDS), pH and duration of immersion on the IE of PVA-Zn2+ system. To analyse the protective film formed on the metal surface. Design/methodology/approach - The IE has been evaluated by weight loss method. The protective film was analysed by FTIR and fluorescence spectra. Findings - A formulation consisting of 100?ppm of PVA and 75?ppm of Zn2+ offered 81 per cent IE to carbon steel immersed in a solution containing 60?ppm of Cl-. A synergistic effect on inhibition of a combination of PVA and Zn2+ was observed during the tests. The protective film consisted of the Fe2+-PVA complex and Zn(OH)2. It was found to be UV-fluorescent. When SDS was added to the PVA-Zn2+ system, the mixture showed maximum IE at the critical micelle concentration (200?ppm) of SDS (an anionic surfactant). The oxygen-scavenging effect of Na2SO3 increased as the concentration of Na2SO3 was increased. At lower concentrations of Na2SO3, the transport of the inhibitors played a more major role than did the removal of dissolved oxygen. As the pH value was increased, the IE of the PVA-Zn2+ system decreased. As the duration of immersion was increased, the IE was observed to decrease. Research limitations/implications - Electrochemical studies such as polarization and AC impedance spectra will enlighten more on the mechanistic aspects of corrosion inhibition. Practical implications - If this study is carried out at high temperature under simulated conditions, the findings may find applications in cooling water systems. Originality/value - The role of transport of inhibitors towards the metal surface from the bulk of the solution, formation of micelles by surfactants, removal of dissolved oxygen by oxygen scavenger, competition between formation of insoluble iron-inhibitor complex on metal surface and formation of soluble iron chloride in influencing the inhibitive property has been investigated. The protective film was analysed by FTIR spectra and fluorescence spectra.

Notes: Purpose - To investigate the inhibiting effect of the cationic surfactant cetyl trimethylammonium chloride (CTAC) on aluminum (Al). Design/methodology/approach - Pure aluminum rods were immersed in hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions for weight-loss tests and potentiostatic polarization measurements. Findings - The inhibition action depends on the concentration of the inhibitor, the concentration of the corrosive media, and the temperature. The inhibition efficiency in NaOH was higher than that in HCl solutions. In both acidic and basic media, the increase in temperature resulted in a decrease of the inhibition efficiency and a decrease in the degree of surface coverage. The results were indicative of increased aluminum dissolution with increasing temperature. It was found that adsorption of CTAC on the aluminum surface follows Temkin's isotherm in HCl and Langmuir's isotherm in NaOH. Originality/value - Clarifies the effects of concentration and temperature on the inhibition efficiency of a cationic surfactant on aluminum.

Notes: Purpose - To present some new designs of magnetic fluid exclusion seals for rolling bearings and possibility to use them in modern industrial sealing applications. Design/methodology/approach - In the paper is given principle of magnetic fluid sealing technology and are presented new designs of magnetic fluid exclusion seals for rolling bearings, such as compact magnetic fluid seals, two-stages seals being combination of magnetic fluid seal and labyrinth seal or radial lip seal, magnetic fluid seals with "floating" magnetic system. This paper also shows examples of their application in various rotating process equipment. Findings - Provides information about new designs of bearing seals and gives the main advantages of these seals over other types, such as total tightness, low viscous drag, maintenance-free service and high reliability. Originality/value - This paper offers some new designs of high-performance magnetic fluid exclusion seals for rolling bearings and points their practical applications.

Notes: Purpose - The main objective of this study was to obtain the flow restricting capacity by determining their flow coefficients and to investigate the unsteady flow with low Reynolds number in the flow-restricting devices such as orifices and capillary tubes having small diameters. Design/methodology/approach - There is an enormous literature on the flow of Newtonian fluids through capillaries and orifices particularly in many application fields of the mechanical and chemical engineering. But most of the experimental results in literature are given for steady flows at moderate and high Reynolds numbers (Re〉500). In this study, the unsteady flow at low Reynolds number (10〈Re〈650) through flow-restricting devices such as orifices and capillary tubes having very small diameters between 0.35 and 0.70?mm were experimentally investigated. Findings - The capillary tubes have much more capillarity property with respect to equal diameter orifices. Increasing the ratio of capillary tube length to tube diameter and decreasing the ratio of orifice diameter to pipe diameter before orifice increase the throttling or restricting property of the orifices and the capillary tubes. The orifices can be preferred to the capillary tubes having the same diameter at the same system pressure for the hydraulic systems or circuits requiring small velocity variations. The capillary tubes provide higher pressure losses and they can be also used as hydraulic accumulators in hydraulic control devices to attenuate flow-induced vibrations because of their large pressure coefficients. An important feature of the results obtained for capillary tubes and small orifices is that as the d/D for orifices increases and the L/d reduces for capillary tubes, higher values C are obtained and the transition from viscous to inertia-controlled flow appears to take place at lower Reynolds numbers. This may be explained by the fact that for small orifices with high d/D ratios and for capillary tubes with small L/d ratios, the losses due to viscous shear are small. Another important feature of the results is that the least variations in C for small orifices and the higher variations in C for capillary tubes occur when the d/D and L/d ratios are smallest. This has favourable implications in hydraulic control devices since a constant value for the C may be assumed even at relatively low values of Re. Originality/value - To the authors' knowledge, there is not enough information in the literature about the flow coefficients of unsteady flows through capillary tubes and small orifices at low Reynolds numbers. This paper fulfils this gap.

Notes: Purpose - To provide new observations about dynamic strain ageing in medium carbon microalloyed steels which are used for automotive applications. Design/methodology/approach - The present work aims to provide theoretical and practical information to industries or researchers who maybe interested in the effects of dynamic strain ageing on mechanical properties of microalloyed steel. The sources are sorted into sections: introduction, experimental procedure, results and discussion, conclusion. Findings - Microalloyed medium carbon steel was susceptible to dynamic strain ageing where serrated flow is observed at temperatures between 200 and 350°C. In this temperature regime, ultimate tensile strength and proof stress exhibit maximum values, however, elongation to fracture showed a decrease until 250°C, after which it increased. Above 350°C, a sharp decrease in tensile strength and proof stress were observed. Abrasive wear resistance of the microalloyed medium carbon steel was also increased at temperatures between 200 and 350°C due to dynamic strain ageing. Research limitations/implications - A search of the literature indicated that although there is considerable volume of information related to dynamic strain ageing in mild steel or in low-carbon steel no extensive investigation has been made of dynamic strain ageing in microalloyed steel due to the ease with which nitrogen is combined AlN, VN, NbN, etc. which perhaps increase its implications. Practical implications - A very useful source of information for industries using or planning to produce microalloyed steels. Originality/value - This paper fulfils an identified resource need and offers practical help to the industries.

Notes: Purpose - To study the combined effects of permeability and couplestresses on the performance characteristics of a secant-shaped porous slider bearing lubricated with Stokes couplestress fluid. Design/methodology/approach - The modified Reynolds type equation governing the fluid film pressure is derived on the basis of Stokes microcontinuum theory of couplestress fluids by using Beavers-Joshep slip boundary conditions at the fluid-porous interface. The modified Reynolds equation is solved analytically and closed form expressions are obtained for the fluid film pressure, load carrying capacity, frictional force and centre of pressure. Findings - The bearing characteristics are computed for various values of the couple stress parameter, slip parameter and the permeability parameters. It is found that, the effect of couple stress is to increase the load carrying capacity and to decrease the coefficient of friction as compared to the Newtonian case. However, the effect of permeability parameter is to decrease the load carrying capacity. It is also found that, the effect of couple stresses is to shift the center of pressure towards the outlet edge. Research limitations/implications - The end effects are neglected in the analysis and these can be included in the study by considering full three-dimensional problem. Practical implications - Reduction in the load carrying capacity due to the presence of porous facing can be compensated by the use of lubricants containing additives of proper size. As a result the bearing performance can be improved. Originality/value - This paper provides closed form expressions for the bearing characteristics and are analyzed with respect to non-dimensional parameters, viz. couplestress parameter, slip parameter and permeability parameter. This paper offers help to design engineers to design efficient bearing systems.

Notes: Purpose - Oil-in-water (O/W) emulsion has been used in industrial rolling mills for many decades, but its lubrication mechanism is still not adequately understood. There is a need to understand the role of chemical ingredients and emulsifier in lubrication and tribological characteristics of rolling oil. With this purpose, the authors selected three commercially available O/W emulsions of different generations and of known industrial performance. The aim is to understand the lubrication mechanism of these rolling oils and to correlate the laboratory findings with that of industrial rolling mills. Design/methodology/approach - The lubrication mechanism has been studied with the help of an ultra thin film interferometry EHD test rig, an advanced experimental rolling mill and a Coulter LS 230 instrument. Film thickness, rolling parameters and droplet size were measured. The coefficient of friction was computed with the help of the measured values of rolling parameters. Emulsion stability and saponification value (SAP) of the selected emulsions were also determined. The results of film thickness, rolling parameters and droplet size have been presented. The lubrication mechanism of the emulsions has been explained on the basis of film thickness, droplet size, emulsion stability, SAP value and coefficient of friction. Findings - Results of the present study reveal that chemistry of O/W emulsions plays an important role in their film forming and tribological behavior. Rolling emulsions of relatively low stability, higher droplet size and high SAP value are found to provide better lubrication and lower coefficient of friction. The results of the present study correlate well with the actual industrial experience except those obtained on EHD test rig. Research limitations/implications - Coulter LS 230 instrument was available with M/s LUBRIZOL CORP., USA. Only limited study on droplet size was carried. Although the study carried out has given good information but it would have been more practical if the emulsion samples taken from the experimental mill stand would have been studied for droplet size. Practical implications - From understanding point of view of lubrication mechanism of O/W emulsion, it will be useful for oil technologists, tribologists and rolling mill users. Originality/value - The study is original in nature and gives information on lubrication mechanism of O/W emulsions in steel cold rolling of steel strips.

Notes: Purpose - Surface roughness is an important parameter in manufacturing engineering with significant influence on the performance of mechanical parts. Failures, sometimes catastrophic failures, leading to high costs, have been imputed to a component's surface roughness. Owing to the need for improvement of machining parameters in order to obtain a prescribed surface roughness, new developments have been recently investigated. This work aims to report on a study of an optimisation model based on genetic algorithms (GAs). Design/methodology/approach - The developed algorithm considers a machining parameter data population obtained from experimental tests. The exchange of structured information based on natural selection principles and "survival-of-the-fittest" allows the combination of solutions in a sequence of generations leading to the best solution. Findings - Over standard experimental design methodologies the proposed GA approach shows advantages in finding the optimal conditions under the imposed constraints. Indeed the quality of the produced surface roughness cannot be evaluated using only a criterion. This GA method determines the combined effects of the input parameters to the optimal machining parameter. Originality/value - A new methodology for determining optimal machining parameters in dry turning based on the measurement of the surface roughness is proposed. The numerical and experimental developed model can be used with success on further applications with industrial interest.

Notes: Purpose - To prevent damages of machinery elements and enhancing life lubrication by using new surface engineering techniques. Design/methodology/approach - A new "wet" coating technique offers an easy and promising route to modify steel surfaces. The design of surface coatings and the results of an official bearing test are presented. Findings - Based on common bearing tests (e.g. DIN 51819), wear behaviour and tribological properties of modified surfaces are verified. Research limitations/implications - Our actual research proves an enhanced tribological behaviour in the case of improving surface properties. In contrast, to the common vapour deposition techniques the "wet" coating method seems to offer an alternative route to get surfaces with enhanced tribological properties. Practical implications - The technique of "wet" coating offers an easy route to modify steel surfaces of all kinds of bearings. Originality/value - Pre-polymer coating provides a promising future technique for surface engineering.

Notes: Purpose - Provide tribological information about the applicability of multi-layer carbon-chromium composite coatings to gears. Discuss the protection provided against scuffing failures, wear and the influence on gear power losses. Design/methodology/approach - Several screening tests, such as Rockwell indentations, ball cratering, pin-on-disc and reciprocating wear tests, were performed in order to evaluate the adhesion to the substrate and the tribological performance of the carbon/chromium composite coating. Afterwards, twin-disc tests were performed at high contact pressure and high slide-to-roll ratios to confirm the good adhesive and tribological properties of the coating under operating conditions similar to those found in gears. Gear tests were performed in the FZG machine in order to evaluate the anti-scuffing performance of the carbon/chromium coating using additive free gear oils. Finally, the carbon/chromium composite coating was also applied to the gearing in a gearbox and its influence on the gearbox efficiency was analysed. Findings - The C/Cr has got very good adhesion to the steel substrate, provides low friction coefficients between contacting solids in relative movement, gives excellent protection against scuffing and wear reduction in gears, and promotes a slight improvement of the gears efficiency. Research limitations/implications - The protection of this carbon/chromium coating against gear micro-pitting should be investigated. Practical implications - This study confirms the applicability of this coating to industrial gear applications, especially in two particular applications: severe applications involving high contact pressures and high sliding, frequent start-ups and inefficient lubrication; and acting as tribo-reactive material and substituting non-biodegradable and toxic additives in environmental lubricants. Originality/value - This work validates and quantifies the influence of this C/Cr multi-layer composite coating in gear applications in terms of adhesion to the substrate, anti-scuffing performance and efficiency.

Notes: Purpose - Wear behavior of boronized GGG-80 ductile cast iron were studied against WC-Co ball for determining the effect of boronizing time and temperature. Design/methodology/approach - Ball on disk arrangement was used for determination of tribological properties of boronized ductile cast iron depending on process time and temperature. Boronizing treatment was performed on GGG-80 ductile cast iron using salt bath immersion boronizing technique at 850 and 950°C for 2-8?h. Friction and wear tests were carried out at dry test conditions under 2, 5 and 10?N loads with 2.5?m/min sliding speed. Findings - The result showed that the friction coefficient values ranged from 0.12 to 0.2 depending on the process parameters. The higher the treatment temperature and the longer the treatment time, the thicker the boride layer, the more the FeB phase and the higher the specific wear rate became. The specific wear rate of boronized ductile cast irons depending on process time, temperature and applied load against WC-Co ball ranged from 1.25?×?10-5 to 42.45?×?10-5?mm3/Nm. Values of coefficient of boronized ductile cast irons increases with increase in load in the wear test and increase in boronizing time and temperature. Research limitations/implications - The study deals with only ductile cast irons and their tribological properties. Practical implications - The results are very useful for practical applications and academic study. There is a little number of studies on the boronizing of cast irons. This study will be helpful for the researcher studied on boronizing of cast irons. Originality/value - The properties of the tribological properties of ductile cast irons have not explained detail in the earlier study. There are new results in this study on the tribological properties of boronized ductile cast irons. Because of this, the paper is original.

Notes: Purpose - To provide a suitable useful mixing ration of nano-sized molybdenum disulfide and commercial common molybdenum sulfide (MoS2) particles (approximately 1.5?µm in diameter) in liquid paraffin, which can lead to a better tribological performance. Design/methodology/approach - The MoS2 nanoparticles and commercial common MoS2 particles (approximately 1.5?µm in diameter) were dispersed in liquid paraffin with different concentrations and ratios by means of ultrasonic in order to study their lubrication capacity, friction reduction and wear resistance. The tribological experiments were carried out by MQ-800 four-ball tribometer, in which extreme pressure, wear scan diameter and friction coefficient were measured. It was analyzed that the chemical status of elements on the rubbed surface by X-ray photoelectron spectroscopy (XPS), and it was observed that the surface topography of wear scan by scanning electron microscope (SEM). Findings - The results showed that the loading capacity of liquid paraffin with different kinds of MoS2 particles were increased with their contents. The liquid paraffin containing the mixture of MoS2 nanoparticles and common MoS2 particles has a better wear resistance, friction-reducing performance and extreme pressure property than the liquid paraffin containing pure common MoS2 or pure nano-MoS2 particles. The optimal mixing ratio of nano-MoS2 and common MoS2 is 20?wt percent, the loading capacity reaches the highest value. By XPS and SEM it was suggested that the difference in the tribological performance between MoS2 nanoparticles and MoS2 common particles was attributed to the surface and interfacial size-effect of nanoparticles and the formation of molybdenum trioxide thin film on the rubbed surface. Research limitations/implications - It is not studied that the effects of mixing of common MoS2 and nano-MoS2 in the actual lubricating oil with various additives. Practical implications - It provided a basic research results and data for the application of nano-MoS2 particles. Originality/value - The mixing of nanoparticles and non-nano-sized particles will lead to new tribological results, which is different from results obtained from other nanoparticles before.

Notes: Purpose - The aim of the present work was to study the synergistic effect of HEDP and zinc on inhibition of the corrosion of carbon steel in neutral oxygen-containing chloride solutions, and to investigate the effect of zinc-HEDP molar ratio on the effectiveness of the zinc-HEDP inhibitive mixtures. Design/methodology/approach - The inhibition of the corrosion of carbon steel by zinc-HEDP mixtures in neutral oxygen-containing solutions was investigated in the presence of 0.003?M (106?ppm) chloride. Findings - It was shown that the inhibition by these mixtures depended not only on the zinc/HEDP molar ratio but also on the concentration of both zinc and HEDP. HEDP concentration appeared to be crucial where good inhibition was not achieved at low concentrations and aggressive nature is observed at high HEDP levels. The effectiveness of the zinc-HEDP mixtures enhanced inhibition by increasing the zinc content of the mixture, but the mechanism was only effective to a certain level, above which the inhibition effect declined. The predominant corrosion control mechanism of the zinc-HEDP mixture was on the anodic (metal dissolution) reaction, but it also affected the rate and mechanism of the oxygen reduction reaction. Originality/value - Demonstrates how the effectiveness of the zinc-HEDP mixtures can enhance inhibition by increasing the zinc content of the mixture.

Notes: Purpose - To study the effect of rotation of a zinc/steel cylinder couple on the rate of galvanic corrosion in saline water and a saline water methyl alcohol system. Design/methodology/approach - The weight loss technique was used for calculating the rate of corrosion. variables such as cylinder rotational speed, salt concentration, alcohol volume percentage, and zinc/steel ratio were studied. Findings - The relationship of turbulence and the rate of corrosion were found to fit the equation R=aRe 0.27. The presence of methyl alcohol in a saline water system decreased the rate of corrosion between 58 and 72 percent for a volume percentage of alcohol from 20 to 70 percent. Originality/value - This paper explains the mechanism of galvanic corrosion for a zinc/steel cylinder couple in the turbulent region for saline water and saline water-alcohol systems.

Notes: Purpose - Plasma spray coating technologies are capable of depositing a wide range of compositions without significantly heating the substrate. The objective is to characterise plasma sprayed metallic coatings on a Fe-based superalloy. Design/methodology/approach - NiCrAlY, Ni-20Cr, Ni3Al and Stellite-6 metallic coatings were deposited on a Fe-based superalloy (32Ni-21Cr-0.3Al-0.3Ti-1.5Mn-1.0Si-0.1C-Bal Fe) by the shrouded plasma spray process. The coatings were characterised in relation to coating thickness, porosity, microhardness and microstructure. The high temperature oxidation behaviour of the coatings was investigated in brief. The techniques used in the present investigation include metallography, XRD and SEM/EDAX. Findings - All the coatings exhibited a lamellar structure with distinctive boundaries along with the presence of some porosity and oxide inclusions. The microhardness of the coatings was observed to vary with the distance from the coating-substrate interface. The St-6 coating had the maximum microhardness, whereas the lowest hardness was exhibited by the Ni3Al coating. The phases revealed by XRD of the coatings confirmed the formation of solid solutions, whereas EDAX analysis of the as-sprayed coatings confirmed the presence of basic elements of the coating powders. So far as high temperature oxidation behaviour is concerned, all of the coatings followed the parabolic rate law and resulted in the formation of protective oxide scales on the substrate superalloy. Originality/value - The plasma spray process provides the possibility of developing coatings of Ni3Al as well as commercial available NiCrAlY, Ni-20Cr and St-6 powders on Fe-based superalloy Superfer 800H

Notes: Purpose - To study the early stages of damage by corrosion fatigue (CF) in an austenitic stainless steel using the electrochemical noise (EN) Technique. Design/methodology/approach - Potential and current transients measured between two nominally identical electrodes during CF of an UNS S31603 SS were continuously monitored using a zero-resistance-ammeter at different periods of exposure to seawater. The tests were carried out under cyclic loading of constant amplitude, stress ratio R=0 and load frequency of ?=0.17?Hz. The analysis was focused on both, crack nucleation sites and short fatigue crack growth, and the correlation between corrosion-fatigue cracking and characteristics of potential transients and the associated intensity current. Findings - Measurements of EN, showed a good relationship between the potential transients and current fluctuations with the initiation and growth of inter-granular corrosion-fatigue cracks. The amplitude and frequency of potential transients and the intensity of current transients became more intense as the number of loading cycles increased. The initiation of crack events and small crack growth could be associated with the noise patterns with amplitudes of 20 and 70?mV and current density between 0.10 and 0.60?µA?cm2; while large inter-granular crack growth events, were due to coalescence of small cracks, and could be associated with patterns of 200?mV in amplitude and a cathodic current density of 8.0?µA?cm2. The crack nucleation sites generally were located at grain boundary triple points on the specimen surface. Originality/value - The EN Technique can be a good alternative to evaluate the early stages of damage by CF.

Notes: Purpose - The acceleration of corrosion of rebars in concrete are due to several reasons such as carbonation, chloride attack, influence of microorganisms, etc. The aim of this investigation mainly focused on how the microorganism was involved in the corrosion process and thereby affect a mechanical property of mortar and accelerate the corrosion of steel in mortar. ordinary portland cement (OPC) and portland pozzolona cement (PPC) was used for making mortar specimens. Sodium citrate was used as an inhibitor for the corrosion of steel in mortar. Design/methodology/approach - Compressive strength measurements were conducted for mortar at different ages in the presence of microorganisms to understand the mechanical property of mortar. Potential-time behavior studies were carried out to determine the status of rebars inside the mortar. Weight loss measurements were adopted to quantify the corrosion level due to microorganisms. The microbial count in the water samples at the initial and final exposure period was also examined. Findings - All these studies showed that additions of sodium citrate level of greater than 1 percent by weight of OPC and PPC severely affected both the mechanical and the corrosion resistance properties of OPC and PPC. Microbiological examination reveals that bacteria consume citrates for their survival and thereby increasing the permeability of mortar specimens. Originality/value - Generally, citrates are considered as being good corrosion inhibitor for steel in concrete. However, results from the present study indicated that sodium citrate concentrations only of less than 1 percent by weight of OPC and PPC are suitable for use in concretes that are exposed to heterotrophic bacterial environments.

Notes: Purpose - Because of the peculiar nature of food and agro-processing industries, the industries cannot tolerate corrosion deposits in their production lines. Hence, there is the need to account for corrosion control before and during the production operations. This is more so in Nigeria where there is little or no proper accountability of corrosion cost in all production system. Design/methodology/approach - The industries investigated were grouped into: meat and meat product, dairy and milk, beverages and brewery, confectionery and agro-processing centres. Questionnaires and interview pro forma were used to collect information from ten major factories/outlets in each category. The study involved the use of life cycle costing to assess corrosion management alternatives and to determine the annualized value of each option. Findings - Among the corrosion prevention methods identified in the industries, greasing gave the least cost contribution (15.9 percent) to the total cost of corrosion prevention followed by painting (17.97 percent) and cleaning (66.14 percent) in that order, while the contribution of each corrosion maintenance method to the total cost of corrosion maintenance was, respectively, 13.08, 7.23, 20.73 and 58.96 percent for annual maintenance, repair, rehabilitation and wages of workers. Originality/value - This study reveals some of the control measures commonly adopted for minimizing corrosion damage in some selected food and agro-processing industries in Nigeria. It also investigated the cost implication of each measure and how it affects the present value of processing machineries in each industry. The results of the study have created a state of awareness of corrosion problems to stakeholders, which would encourage preventive actions.

Notes: Purpose - To discover if stress corrosion cracking (SCC) of C-Mn steel is possible at ambient pressure and temperature in a CO-CO2-H2O environment. Design/methodology/approach - Approach involved electrochemical testing, slow strain rate testing (SSRT) and fractography. The chemistry within a crack or crevice during SCC differs from that of the bulk environment. To simulate this condition, a specimen was designed containing a steel plate, microelectrodes and artificial crevice. Electrochemical tests were performed to discover if conditions likely to cause SCC could be achieved. Slow strain rate tests and fractography was also carried out to support the electrochemical data. Findings - Results indicated that CO can adsorb onto the metal and that localized corrosion occurred at defects in the adsorbed CO layer due to CO2, which led to the onset of SCC. Consequently, larger anodic and cathodic currents were measured with or without a crevice, when CO2 was in solution. Similar behaviour was observed on the microelectrodes. Regions of brittle fracture were discovered on the specimen surface after SSRT were conducted in a vapour phase environment. After such tests, the ductility of the steel was found to be impaired. Practical implications - Practically the results could help to predict the potential range in which SCC may occur. Originality/value - Paper is new because previous results were at high pressures. However, results indicate that SCC is a danger at atmospheric pressure. The paper is of value to people in the oil and gas industry.

Notes: Purpose - The cheapest and most rapidly available metal for agro-processing equipment fabrication in Nigeria is plain carbon steel. However, there are some aggressive ions present in raw agricultural and food products, which may attack the steel components of these processing machinery, resulting in their untimely failure in service. The present study investigates the effect of fluid squeezed from cassava tuber on the corrosion behaviour of mild steel. Design/methodology/approach - The investigation involved periodic weight loss measurements of 0.8 per cent carbon and 0.36 per cent carbon steel rods as they were exposed to cassava fluid. The relationships between loss in weight of the exposed samples and exposure period were determined. Models were developed to relate corrosion rate in each environment with total surface area and exposure period. Findings - The results show that 0.36 per cent carbon steel was less affected by corrosion than 0.18 per cent carbon steel, with corrosion intensity in both cases, increasing with duration of immersion. Generally, there was low level of corrosion resistance (high corrosion rate) by the two steel materials. The correlation coefficient between the experimental values of corrosion rates and predicted values (using the developed models) was high. Originality/value - In food and agricultural industries, product quality, health and sanitation issues are the major concerns. The industries cannot tolerate corrosion deposits in the manufactured products. Hence, material selection for machinery fabrication is essential. In line with this, the results of this study indicate that mild steel materials are unsuitable for use in cassava processing without some forms of surface treatment.

Notes: Purpose - To determine if the interim use of liquid waste as a fuel in a catalytic steam reformer unit had any deleterious effect on the long-term life of the reformer tubes. Design/methodology/approach - Standard metallographic techniques were used to prepare representative samples obtained from various sections of the reformer tubes for metallurgical evaluation. Microstructural characterization was carried out in a scanning electron microscope equipped with an energy dispersive X-ray spectrometer. Imaging and elemental analysis was used for the identification of the alloy material, corrosion products and other microstructural features. Findings - Hydrogen was produced in a catalytic steam reformer by cracking methane using natural gas as a fuel. Corrosion of reformer tubes occurred when natural gas fuel was replaced with a liquid waste. Use of liquid fuel waste accelerated the rate of oxidation at the outer tube surface. However, foreign species from the fuel were not transported into the tube material. The heat-resistant steel casting used for this application was susceptible to precipitation of Si-stabilized Ni-Nb Laves phase, thus reducing rupture life of the component. Voids at grain boundaries indicative of creep damage were observed. Practical implications - Although, the interim use of liquid waste fuel appeared not to have damaged the tubes, it was concluded that the expected service life of the tubes may not be realized because of the susceptibility of the material to precipitation of Laves phase. An Fe-base superalloy UNS N08810 or UNS N08811 was recommended as a replacement material for this application. Originality/value - This paper provides an account of a failure analysis study. It identifies incorrect materials selection for a particular application and suggests better alternative along with its justification. The information is deemed useful for plant designers and engineers working in the related industry.

Notes: Purpose - Aims to study inhibitive properties of new compounds that are based on the Wurtzite structure of zinc oxide with an admixture of cobalt using zinc oxide as a reference. Design/methodology/approach - The conditions for the preparation of pigments using different ratios of both cobalt and zinc were investigated. Characterization of these pigments was carried out using spectroscopic methods of analysis via X-ray diffraction, transmission and scanning electron microscopy. Also, evaluations of the pigments prepared, in terms of oil absorption, specific gravity, water-soluble matter and pH, using international standard testing methods was performed. The pigments prepared were incorporated in anticorrosive paint formulations based on medium oil alkyd resin as a binder. The physico-mechanical properties of the relevant paint films were obtained, while their anticorrosive properties were assessed by tests in 3.5 percent NaCl solution for 28 days. Electrochemical measurements based on corrosion rates of paint films also were studied. Findings - The results showed that the anticorrosive protection properties of the pigment prepared were better than with zinc oxide pigment alone. Research limitations/implications - The pigments prepared can be used as reinforcing filler in different rubber and plastic composites providing them with an intense green color. As the concentration of cobalt oxide exceeds 15 percent, the reinforcing and effects decreased and vice versa. Originality/value - Zinc chromate is one of the anticorrosive pigments most frequently used in the formulation of primers. However, its environmental aggressiveness and toxicity severely restrict its use and different green alternatives have been proposed in order to replace it. One such alternative is the pigment evaluated in this paper. New pigment applications, such as reinforcing fillers for rubber and plastic composites, also could be attractive.

Notes: Purpose - To analyze the different approaches used to estimate the cost of corrosion and understand the limitations so as to have proper appropriation in future appraisals. Design/methodology/approach - Four well-known approaches to analysis of cost of corrosion viz., the Uhlig method, the Hoar method, NBS-BCL input/output method and net present value method have been considered in great detail and the impact of these approaches on corrosion economy in different countries has been highlighted. Findings - Uhlig method of estimating corrosion cost always gives a conservative estimate of the direct cost of corrosion. The direct cost of corrosion, as estimated by the Hoar method, is found to be somewhat higher than is the estimate made using the Uhlig method, as shown by Shibata of Japan. The NBS-BCL method of input/output analysis, though apparently more scientific, is subject ultimately to uncertainties in quantifying the capital cost and intermediate output. The net present value method appears to be more realistic than do other approaches as it enables a life cycle costing of each structure/facility to be made and arrives at the most cost-effective corrosion control method. Even though all the above four approaches enable an estimation of direct cost of corrosion, there is no standard approach to assess the indirect cost of corrosion. Originality/value - In a developing economy, each and every industry has to go for systematic corrosion auditing in order to identify and adopt the most appropriate corrosion control measures and effect considerable savings. This paper would be of immense use in that regard.

Notes: Purpose - To provide a selective bibliography for graduate students and new faculty members with sources which can help them develop their academic career. Design/methodology/approach - A range of published (1951-2004) works, which aim to discuss the main parameters of the volatile corrosion inhibition process. The sources are sorted into sections: transport of the volatile corrosion inhibitor (VCI) to the metallic surface, vapour pressure of a VCI, dependence of vapour pressure upon temperature, effect of pH on VCI behaviour, formation and destruction of adsorbed films, and volatile corrosion inhibitor monitors (VCIM). Findings - Provides information about each source, indicating what can be found there and how the information can help. Recognises the lack of real training of many academics before they are expected to take on teaching/researching duties and finds some texts which help. Research limitations/implications - It is not an exhaustive list and apart from several UK and US books all the rest are EU and US publications which perhaps limits its usefulness elsewhere. Practical implications - A very useful list of the most common compounds used as VCIs is reported. Originality/value - This paper fulfils an identified information/resources need and offers practical help to an individual starting out on and academic career and to professional with some experience on corrosion inhibition.

Notes: Purpose - To show the effect of organic compounds containing O and N atoms on the corrosion inhibition of Cu in HNO3 and; the effect of some donating substituent groups on the corrosion inhibition. Design/methodology/approach - A range of published papers (1956-1995), which aim to discuss the effect of organic compounds on the corrosion inhibition process. Two methods were used to determine the rate of corrosion, these methods were weight loss and polarisation. The effect of temperature and concentration were studied. The thermodynamic parameters for the process were computed and discussed. Findings - Provides information about weight loss and polarisation methods and how to prepare the Cu samples before and after tests. This will provide many academics relevant information before teaching or researching duties. Research limitation/implications - The paper may be using withdrawing substituting groups in addition to donating groups, this will improve the discussion, also the paper does not use the technique of impedance spectroscopy for comparison. Practical implications - To use Cu alloy for comparison and to use other compounds with larger molecular weights. Originality value - The use of some phthalimide derivatives as corrosion inhibitors for Cu in HNO3, provide more information on Cu corrosion for academic researchers and provide practical help for starting researchers.

Notes: Purpose - To study the corrosion behavior and discuss the corrosion mechanism of No. 20 carbon steel in water in the presence of sulfide ions. Design/methodology/approach - The mass-loss method, electrochemical tests and surface analysis were used to study the corrosion behavior and discuss the corrosion mechanism of No. 20 carbon steel in water in the presence of sulfide ions. Findings - General corrosion occurred when No. 20 carbon steel was immersed in both test solutions (concentrated sample with S2- added to 0.8?mg/L, and pure concentrated sample with no S2- added). The presence of S2- in test solutions accelerated the corrosion rate of No. 20 carbon steel. Practical implications - In order to prevent No. 20 carbon steel in water with S2- from corroding, S2- must be removed. Originality/value - It was found that the presence of S2- in test solutions accelerated the corrosion rate of No. 20 carbon steel in this paper. Therefore, when water containing sulfide ions is used as the source of make-up water and cooling water, S2- in water must be removed to prevent the pipelines and facilities from corroding. This means the research results can offer theoretical guidelines for the prevention of pipelines and facilities in the power plant from corroding.

Notes: Purpose - Kaolin (hydrated aluminum silicate) is one of few minerals that are found in nature in a relatively pure state which is abundant in many places of the world. In this research, a simple chemical treatment using traces of ammonium molybdate was carried out to enhance the anticorrosive properties of kaolin. Design/methodology/approach - The steps of treatment of kaolin at 1,000°C were estimated. Characterization of three different combinations of aluminum oxide with iron oxide were studied using spectroscopic methods of analysis via X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM). Also, evaluation of the prepared pigments using (oil absorption, specific gravity, water-soluble matter, and pH) international standard testing methods were estimated. Then these prepared pigments were incorporated in anticorrosive paint formulations based on medium oil alkyd resin as a binder, the physico-mechanical and anticorrosive properties of paint films were detected by testing them in 3.5 percent NaCl solution for 28 days. Findings - Introduction of small amounts of ammonium molybdate in kaolin promoted its physico-mechanical and anticorrosive properties. Although, this process of treatment is economically feasible, treated kaolin can replace expensive commercial pigments found in markets with an almost near quality to their performance. Originality/value - Treated kaolin can be applied in many industries beside pigment manufacture, and paint formulations, it can be applied as reinforcing filler in rubber, plastics, and ceramic composites. Also it is applied in paper filling, paper coatings, and electrical insulation.

Notes: Purpose - The main purpose of this study was to investigate the corrosion behaviour of simulated archaeological iron in Cl-, NO3- and HSO3- bearing pollutants. Design/methodology/approach - Periodic wet-dry test, potentiodynamic polarization experiments and surface tension tests were used to study the rule of corrosion rate. Scanning Electron microscopy with EDAX, stereoscopic microscopy and X-ray diffraction were also used to identify the corrosion products and mechanism. Weight loss measurement, electrochemical theory, as well as ions adsorption theory and penetration theory were used to explain the different corrosion behaviour. Findings - The experimental results demonstrated that the attack of anodic ions to the metal at the initial corrosion stage showed great agreement with their surface activity. However, as corrosion progressed, the different reaction mechanisms and the penetration effect of anions as well as the characteristics of the corrosion products (intermediate products and final products) begin to control the corrosion process. Originality/value - The initial corrosion rate was found to show agreement with the surface activity of anions. From a new viewpoint, this paper explains the different corrosion behaviour of Cl-, NO3- and HSO3- anions to simulated archaeological iron and offers reference to the individual who pursues in corrosion and protection of metal.

Notes: Purpose - This paper describes the changing of high-temperature oxidation resistance (HTOR) at the temperature 1,200°C which is dependant on characteristics of alloying and microstructure. The aim of the research was to show a broad problem of using the intermetallic Ni3Al in the production of propulsion aircraft engines because this material has a very high HTOR and low density. Design/methodology/approach - For the estimation of a level of HTOR of Ni3Al (Ni-12Al) and its alloying compositions, a method was used in which samples were heated in ambient atmosphere at 1,200°C for a period of 1,500?h. The samples were weighed every 100?h. The data was obtained for eight different compositions. Findings - The process of researching indicated that a maximum HTOR has the composition Ni-12Al without alloying which is obtaining by dosed directional solidification (DDS) method and having the largest structural stability at 1,200°C. Practical implications - This material is broadly used in the production of valves, electrical heaters, etc. However, these details are obtained by equiaxial casting or powder metallurgy methods. The material obtained by DDS method has higher strength characteristics and may be implicated in many components of aircraft engines (elements of the firing chamber or a stationary blades, etc.). Originality/value - This research presents a new type of microstructure which has a matrix Ni3Al on a base of disordered gamma phase (DDS Method). Currently, this structure has had little studies carried out on it. However, it could become an object for detailed research for process phase precipitation using a super high magnifications.

Notes: Purpose - To evaluate the inhibition efficiency of 1-methyl 2-mercapto imidazole (MMI) in controlling the corrosion of carbon steel in sulphuric acid and to study its action mechanism. Design/methodology/approach - The effect of concentration, immersion time and temperature on the behaviour of this inhibitor has been studied using weight loss, d.c. polarisation and a.c. polarisation techniques. Findings - The results show that MMI is a mixed type inhibitor. Changes in impedance parameters (charge transfer resistance, Rt; and double layer capacitance, Cdl) were indicative of adsorption of MMI on the metal surface, leading to the formation of a protective film that grew with the increasing exposure time. Adsorption of MMI on the carbon steel is found to obey the Langmuir adsorption isotherm. The inhibition efficiency of MMI is temperature-independent and its addition leads to a small increase in activation corrosion energy. Research limitations/implications - Surface analytical techniques such as X-ray photoelectron spectroscopy and Auger spectroscopy can enlighten more on the mechanism of corrosion inhibition. Originality/value - A survey of literature has shown that no work using electrochemical techniques has yet been done on MMI as corrosion inhibitor for carbon steel in sulfuric acid.

Notes: Purpose - To investigate the capability of a series of nitrogen-based heterocyclic organic compounds in inhibiting corrosion of iron in HCl and elucidate the dominant active form of the applied compounds during the adsorption process to explore the mechanism of their action. Design/methodology/approach - The tested compounds were pyrimidine containing compounds, which were selected, based on molecular structure considerations. Gravimetric method has been applied with various electrochemical techniques (polarisation resistance, polarisation curves and electrochemical impedance spectroscopy) to investigate inhibition efficiency and mechanism. Findings - The inhibiting action of the investigated pyrimidine containing compounds depends primarily on their concentration and molecular structure. These compounds act as mixed type inhibitors and function via adsorption on the surface, which follows Frumkin adsorption isotherm. The inhibition by the tested pyrimidine derivatives could be attributed to their chemisorption on the metal surface forming donor/acceptor type of bond between the inhibitor molecules and the vacant d orbitals of the surface iron atoms. Contribution from electrostatic adsorption, via interaction between the protonated form of the inhibitor and the charged metal surface, is also possible. Research limitations/implications - The applied inhibitors were tested in the presence of chloride ions as a corrosive medium. Whether these inhibitors will function well in the presence of other ions that are typically present in natural corrosive environment is unknown. Originality/value - This paper provides useful information regarding inhibition effect of pyrimidine and series of its derivatives. The outcome of this work contributes to better understanding of the mechanism of inhibition by this class of N-based heterocyclic organic compounds.

Notes: Purpose - Cutting fluids despite playing an important role in metal cutting have considerable environmental impact. Inert gaseous metal cutting environments were investigated with the aim of removing soluble oil cutting fluids from metal cutting operations.Design/methodology/approach - Industrially reproducible cutting tests were devised, where an austenitic stainless steel and En32 low carbon steel material was milled in a range of different cutting environments. Tool life was measured for tests carried out in a number of gaseous environments and results were then compared with test results from conventional flood cutting environments.Findings - Low oxygen gaseous environments were compared with conventional cutting environments and a considerable flank wear reduction has been recorded using CVD coated tooling. Additionally flood coolant environments have been seen to promote chemical wear after the initial breakdown of coatings leading to rapid flank wear during milling of both En32 and austenitic stainless steel.Research limitations/implications - Only a limited number of work/tool material combinations have been investigated. A more detailed and exhaustive investigation is required to ascertain the scope of the improvements for a range of tool work combinations. This will assist in understanding the underlying reasoning for the tool life enhancement reported.Practical implications - All experimentation carried out is industrially reproducible. This work, therefore, proposes an environmentally clean alternative to the use of emulsified oils in metal cutting operations in order to exploit cost savings and improved operator working environments.Originality/value - Distinct operational performance improvements have been demonstrated in the form of extended tool life for metal cutting operations performed in a non-polluting cutting environment. These findings could herald widespread advantages within the metal cutting community.

Notes: Purpose - To study and estimate changes of various properties upon use of engine oil by different methods.Design/methodology/approach - By viscosity measurement, pH measurement, Fourier transform infra-red spectroscopic analysis and UV-Visible (Ultraviolet and visible rays) spectroscopic analysis.Findings - Some specific changes in additives of the oil upon use could be traced.Practical implications - Correct choice for additives for a particular use may enhance the oil life and also protect the engine from damage.Originality/value - The findings may be important to the lube oil producers and the users.

Notes: Purpose - To study some tribochemical properties of tetrazole derivatives, n-hexadecanyl (1H-tetrazol-1-yl) acetate (HTA) and 1-phenyl-5-(octylthio)-tetrazole (PCT) as lubricating oil additives in hydrogenised oil, and estimate the action mechanism.Design/methodology/approach - The two tetrazole compounds were synthesized, and added them in hydrogenised oil with different concentrations. Their anti-wear properties were evaluated with a four-ball machine, the wear scar was analyzed with a X-ray photoelectron spectroscopy (XPS).Findings - The novel compounds possess good anti-wear, friction reduction properties and good load-carrying capacity. According to the XPS results, the novel compounds were migrated onto the surface of the steel balls and adsorbed on the surface. The two additive compounds, themselves, and their decomposers contributed to the corresponding tribological performances. With S element contained in the compound PCT, the influence on the load-carrying capacity of the base oil was enhanced. It may be due to the formation of S2- and SO42- compounds on the worn surface which could form a protective film.Research limitations/implications - Their antioxidant, anticorrosion, anti-wear properties are not estimated.Practical implications - Two useful EP and AW lubricating oil additives were synthesized, and maybe it is the potential industrial applied lubricating oil additives.Originality/value - This paper provided a study way of some N-containing heterocyclic compounds as lubricating oil additives.

Notes: Purpose - To examine the mechanical properties of TiN PVD coated Ti-6Al-4V alloy through three-point bending tests. Design/methodology/approach - Ti-6Al-4V alloy is cut in size and polished and cleaned chemically before TiN PVD coating process. INSTRON three-point bending equipment is used to conduct the bending tests for TiN coated and uncoated workpieces. During the tests, the load and displacement characteristics were recorded. The tests were terminated when the coating failed. Micrographs of surface and crack sites were obtained by SEM. Findings - Coating failure occurs due to shearing effect on the tensile surface. The spalling and buckling of the coating on the compressive surface are observed. The compressive stress generated on the top surface (where the indent is in contact) did not cause adhesive failure of the coating. Moreover, cohesive cracks occur on the tensile surface of the coating. The crack ledge under the action of shear stress appears on the tensile surface of TiN coating and multi cracking of coating is resulted. The crack spacing is small indicating sliding and splitting separation between the adjacent columns in the coating. Research limitations/implications - The tests can be extended to include the duplex treated workpieces such as the heat treatment of surface prior to TiN coating. This enhances the interface properties of the coating and base alloy. Practical implications - The results can be used to assess the TiN coating applications in cutting tools, particularly drill bits and punches. Originality/value - This paper provides information on mechanical behavior of TiN coating when subjected to bending force and offers practical help for the researchers and scientists working in the coating area.

Notes: Purpose - Nowadays, green cutting has become the focus because of its ecological problem and the necessary environment protection, so that the research on experimentation of green cutting with water vapor as coolant and lubricant is studied because water vapor has many benefits of cheapness, no pollution, no harm and no recycling and handling. Design/methodology/approach - The vapor generator and the vapor feed system are manufactured, the distribution of temperature and velocity of vapor jet flow are simulated by MATLAB program, and under the conditions of compress air, oil water emulsion, water vapor as coolant and lubricant and dry cutting, respectively, the turning experimentation of comparison which the tool is YT15, and the working material is steel 45. Findings - Water vapor, as coolant and lubricant, the cutting force is reduced, respectively about 30-40, 20-30 and 10-15 percent by comparing to dry cutting, compressed air and oil water emulsion. The cutting temperature is, respectively about 30, 40 and 50 percent with the other conditions of dry cutting, compressed air and oil water emulsion. The friction coefficient and the chip deformation coefficient are correspondingly decreased and the surface roughness value has been diminished too. Through analysis of the experimental results, water vapor as coolant and lubricant possesses better lubricating action because of the excellent penetration performance and the low lubrication layer shearing strength of water vapor. Originality/value - Water vapor as coolant and lubricant provides a novel method for realizing no contamination green cutting.

Notes: Purpose - The purpose of presented study is to investigate the development of the barreling obtaining the variation of the surface area during upsetting of cylindrical specimens for various metals and alloys. Design/methodology/approach - Variations of the surface areas were first obtained analytically using mathematical equations for uniform and non-uniform upsetting. Barreling contours were accepted as circular segments in the development of the equations. In the experimental part of the study, barreling radii and other related dimensions of upset specimens were measured and inserted into the developed equations in order to obtain the variations of total specimen surface areas. Findings - As it is expected, barreling effects the variation of total surface areas of the specimen. It can be concluded that the total surface area first decreases at low upset ratios for all the test materials and then begins to increase as the upset ratios increases. Consequently, total surface areas for non-uniform upsetting are always smaller that those of uniform upsetting. Research limitations/implications - Five kinds of materials were used in the experimental part of the study. Specimens were also upset without lubrication. A relatively slow hydraulic press was used during the experiments with 5?mm/s ram speed. Practical implications - Although the study has not direct implications for the practical purposes in forging area, results can be used as a very useful source of information for researchers in this field to plan their studies. Variation character of total surface area obtained in the study may give useful data in analyzing the deformation patterns in upsetting. Originality/value - The effects of barreling on the material behavior in upsetting for non-uniform conditions were analyzed with respect to variation of total specimen surface area. This point of view may be extended for different materials and friction conditions.

Notes: Purpose - To make a derivation of the load-carrying capacity of elastohydrodynamic lubrication for special operating conditions, i.e. extremely heavy loads or extremely low rolling speeds based on the Newtonian fluid model by taking the Grubin-type EHL inlet zone analysis, justify the load-carrying capacity of elastohydrodynamic lubrication film in these operating conditions, and propose future trends of the research in EHL and mixed EHL based on the obtained results in the present paper. Design/methodology/approach - A Grubin-type EHL inlet zone analysis is carried out for the isothermal EHL of line contacts in special operating conditions, i.e. extremely heavy loads or extremely low rolling speeds based on the Newtonian fluid model. Comparison is made between the central EHL film thickness in line contacts, respectively, predicted by conventional EHL theories and accurately predicted from the present analysis for these operating conditions. An interpretation is made for the EHL film thickness in these operating conditions by taking the approach of the transportation and flow of the fluid through elastohydrodynamic contact when the EHL film is, respectively, thick and molecularly thin in the Hertzian zone. Conclusions are drawn on the load-carrying capacity of EHL, EHL contact regimes and mixed EHL regimes in these operating conditions. Findings - The present EHL inlet zone analysis shows that the EHL film thickness in the Hertzian zone is on the nanometer scale and the lubricant is non-continuum across the film thickness in the Hertzian zone at relatively heavy loads in line contact EHL when the dimensionless rolling speed is lower than the dimensionless characteristic rolling speed Uch=0.0372W1.50/G. In this case, the central EHL film thickness in line contact EHL predicted by the conventional EHL theory may be several orders of magnitudes higher than that accurately predicted. This difference may be greater for heavier loads.The present results for line contact EHL based on the Newtonian fluid model show that in line contact EHL, for relatively heavy loads and the dimensionless rolling speed lower than the dimensionless characteristic rolling speed Uch=0.0372W1.50/G, the EHL analysis needs to further incorporate the lubricant non-continuum effect across the film thickness in part of the lubricated area to investigate the EHL film thickness and the EHL film pressure in the contact in this very low film thickness condition; only the results based on such an analysis are believable for the EHL stage where the lubricant film thickness in the Hertzian zone approaches to zero and then vanishes; the results for EHL based on the Newtonian fluid model is unable to conclude that the EHL film thickness in the Hertzian zone is zero and dry contact occurs between the contact surfaces in EHL in any operating condition for ignoring the lubricant non-continuum regime governing the EHL stage preceding the occurrence of the zero lubricant film thickness in EHL. Practical implications - A very useful source of information for academic scientists, engineers and tribologists who are engaged in the study and application of the theory of elastohydrodynamic lubrication. Originality/value - A derivation is first carried out for the isothermal EHL of line contacts in extremely heavy loads or extremely low rolling speeds by taking the Grubin-type EHL inlet zone analysis by the present paper. Results and conclusions on the load-carrying capacity of EHL in these operating conditions are first strict and thus convincing. These results are also original in clarifying the future trends of the researches in EHL and mixed EHL.

Notes: Purpose - Engine oil degrades in quality during its use and after certain period of time the oil needs to be changed depending upon its condition. The purpose of this paper is to design and develop an online condition monitoring device for engine oil. Design/methodology/approach - Based on the previous works in this line and some testing of used oils in the laboratory, the correlation of change in colour with other properties were identified. An optical colour sensor was then designed and developed which can transform the darkness of oil colour into electrical resistance. A series of tests were undertaken to calibrate the system for its correctness. Findings - This type of sensor provides the information about the condition of the oil and also can inform about the probable time for drain-off of the oil. Practical implications - Engine oil changes are normally done by schedules which are highly conservative and cost the user as the oil is changed when it could be still used for some time. Use of an online sensor will minimize the cost on lubricants to some extent. Originality/value - The device is of great value to the users of IC engines as it not only reduces the cost on lubricants but also informs the user about the present condition of the oil.

Notes: Purpose - Anisotropic conductive adhesive film (ACF) is used for very fine pitch applications in the microelectronics industry, such as flip chip (FC) technology. During the bonding process, bumps on the chip and pads on the substrate are first aligned and then heat and pressure are applied so as to apply thermal energy to the ACF for curing and to cause permanent plastic deformation of the conductive particles. Consequently, a permanent electrical and mechanical contact is formed between the bumps and the pads. The purpose of this study is to investigate the effect of the size and location of any voids in the ACF during subsequent solder reflow processes necessary for SMT component attachment. The paper also investigates the use of a protective aluminium cover during such reflow cycles, which reduces the temperature inside the ACF, and therefore, the stresses inside the ACF, especially when voids exist. Design/methodology/approach - In this study, the ACF is a temperature dependent material having various void sizes, entrapped within the ACF. A finite element method is used to analyse the stresses within a FC on flex assembly. Findings - The results indicate that the smaller the void, the larger the stress concentration. Also, the von Mises stress was found to be larger in the upper portion of the ACF, near the chip, than in the lower portion of the ACF nearer to the flexible substrate. This implies that the four corners of a void are seen to be the most likely site for crack initiation and propagation and therefore, for failure to occur. Moreover, the temperature profile of the reflow cycle and the locations of the voids have also been shown to affect the stress level within the ACF. Originality/value - The value of this paper is to show how the presence of voids may affect the reliability of a FC assembly.

Notes: Purpose - Optimisation of the package design in order to reduce stresses in a plastic small outline J-lead (SOJ) package and to thereby prevent fractures during the infrared soldering process. Design/methodology/approach - Finite element (FE) modelling was used, both with and without crack tip-modelling. A design of experiment (DOE) approach was used to reduce the number of FE models required. Findings - The optimum design values for minimization of thermal stress and the prevention of fracture were found to be different. The results allow the values of design variables such as the dimensions and material properties of the IC package. Practical implications - To reduce the stresses and thereby prevent fracture, the values of the Young's modulus and coefficient of thermal expansion of the epoxy moulding compound should be reduced. Originality/value - The work has used both stress analysis and fracture mechanics analysis along with DOE to identify the design values which simultaneously reduce the thermal stresses and prevent the fracture of the IC package.

Notes: Purpose - Historically, tin-lead solder has been a commonly used joining material in electronics manufacturing. Environmental and health concerns, due to the leaching of lead from landfills into ground water, have necessitated legislation that restricts the use of lead in electronics. The transition from tin-lead solder to a lead-free solder composition is imminent. Several alternative solder alloys (and their fluxes) have been researched for electronics assembly in the last few years. The objective of this research was to develop a systematic selection process for choosing a "preferred" lead-free solder paste, based on its print and reflow performance. Design/methodology/approach - After a detailed study of industry preferences, published experimental data, and recommendations of various industrial consortia, a near eutectic tin-silver-copper (SAC) composition was selected as the preferred alloy for evaluation. Commercially available SAC solder pastes with a no-clean chemistry were extensively investigated in a simulated manufacturing environment. A total of nine SAC pastes from seven manufacturers were evaluated in this investigation. A eutectic Sn/Pb solder paste was used as a baseline for comparison. While selecting the best lead-free paste, it was noted that the selected paste has to perform as good as, if not better than, the current tin-lead paste configuration used in electronics manufacturing for a particular application. The quality of the solder pastes was characterized by a series of analytical and assembly process tests consisting of, but not limited to, a printability test, a solder ball test, a slump test, and post reflow characteristics such as the tendency to form voids, self-centring and wetting ability. Findings - Each paste was evaluated for desirable and undesirable properties. The pastes were then scored relative to each other in each individual test. An aggregate of individual test scores determined the best paste. Originality/value - This paper summarizes a systematic approach adopted to evaluate lead-free solder pastes for extreme reflow profiles expected to be observed in reflow soldering lead-free boards.

Notes: Purpose - Anisotropic conductive film (ACF) offers miniaturization of package size, reduction in interconnection distance and high performance, cost-competitive packaging and improved environmental impact. However, a major limitation for ACF is the instability caused by thermal warpage. The purpose of this paper is to study the effects of thermal warpage on contact resistance in real time i.e. make online measurements of contact resistance fluctuations while the assembly undergoes thermal shock. Design/methodology/approach - The ACF assemblies are subjected to thermal cycling with different temperature profiles that have peak temperatures either below or above the glass transition temperature (Tg) of the ACF. The flex substrate used was made of polyimide film, with Au/Ni/Cu electrodes and a daisy-chained circuit matched to the die bump pattern. The ACF used was based on epoxy resin in which nickel and gold-coated polymer particles are dispersed. A comparative study was carried out on the results obtained. Findings - The results showed that the glass transition temperature (Tg) of the ACF material plays an important role in the high temperature contact resistance. Above Tg, the ACF matrix becomes less viscous, which reduces its adhesive strength and allows the bumps on the chip to slide away from the pads on the substrate. Even though a flex substrate was used in this study, the sliding effect is severe at the corner bumps of the chip, where cumulative forces are generated due to the thermal expansion mismatch. For every thermal cycling profile, there is an incubation period encountered from this work that would have a significant impact in the application of ACF. After the incubation period the contact resistance increased rapidly and the assemblies were therefore no longer reliable. Originality/value - The work in this paper focuses on contact resistance changes during thermal shock. The paper discusses the reliability issue of ACF during thermal warpage, which is useful to industries using ACF for flip-chip assemblies.

Notes: Purpose - To investigate the degradation of lead free solder heat-sink attachment by thermal shock. Samples with high voiding percentages were selected for the investigation in order to get information on the significance of voids on the reliability of Sn-Ag-Cu heat-sink attachment. Design/methodology/approach - Through the use of X-ray, C-mode scanning acoustic microscopy, dye penetration, cross section and scanning electron microscopy/energy-dispersive X-ray tests, the degradation of Sn-Ag-Cu heat-sink attachment during thermal shock cycling was evaluated. Findings - The results showed that the Sn-Ag-Cu heat-sink attachment where the area of voiding was 33-48 per cent survived 3,000 thermal shock cycles, although degraded. The main degradation mechanism for the solder attachment was not solder fatigue but interface delamination due to Kirkendall voids at the Cu/Cu3Sn interface. It was found that the large voids in the Sn-Ag-Cu heat-sink attachment were not significantly affecting the solder joint lifetime. Big differences of intermetallic compound growth behaviour and Kirkendall voids at device/solder and solder/Cu pad interfaces are found and the reasons for this are discussed. Originality/value - This work has clarified the general perception that large voids affect the thermo-mechanical lifetime of solder joint substantially and also provides further understanding of the Sn-Ag-Cu heat-sink attachment degradation mechanism.

Notes: Purpose - Sn-Zn based lead free solders with a melting temperature around 199°C are an attractive alternative to the conventional Sn-Pb solder and the addition of bismuth improves its wetability. Whilst lead-free soldering with Sn-8Zn-3Bi has already been used in the electronics assembly industry, it is necessary to study its low cycle fatigue properties since such data have not been reported up to now. Design/methodology/approach - In this study, displacement-controlled low cycle fatigue testing of Sn-8Zn-3Bi and Sn-37Pb solder joints was done on lap shear samples. The test amplitude was varied whilst the frequency was kept constant at 0.2?Hz and failure was defined as a 50 per cent load reduction. Finite element (FE) modelling was used for analysis and the results were compared to the experimental data. Findings - The microstructure of the Sn-8Zn-3Bi solder showed a mixed phase of small cellular-shaped and coarser needle-shaped areas. Au-Zn intermetallic compounds were observed near the interface from the SEM-EDS observation. The average lifetime for the Sn-8Zn-3Bi solder joints was 17 per cent longer compared to the Sn-37Pb solder joints. The cross section observation indicated that the fatigue cracks propagated along the interface between the solder bulk and the Au/Ni layer. The locations of maximum equivalent stress from the FE simulation were found to be at the two opposite corners of the solder joints, coinciding with the experimental observations of crack initiation. Originality/value - This is believed to be the first time, the low cycle fatigue properties of Sn-8Zn-3Bi solder have been reported.

Notes: Purpose - To apply the design of experiments (DOE) methodology to the problem of cracking of plastic ball grid array (PBGA) packages during the reflow soldering process. Design/methodology/approach - The DOE methodology was used in order to identify the optimum design. CAE was used for the required stress analysis and for integral calculation during crack analysis. Findings - The optimum design to reduce the stress and fracture probability for the PBGA package was obtained and the DOE technique was shown to be very powerful for establishing the optimum design when there are many design parameters. Research limitations/implications - In future research, a robust design methodology could be applied including design for six sigma considering the noise parameters. Practical implications - For better design of a PBGA package, the DOE methodology has been shown to be very useful. Originality/value - In this paper, application of the DOE approach to a PBGA package design in order to reduce the stresses and probability of fracture was attempted for the first time.

Notes: Purpose - To study the effects of design and assembly process conditions on lead-free solder joints for an area array component. Design/methodology/approach - Experiments using SnAgCu solder for assembling plastic ball grid array components on printed circuit boards (PCBs) were carried out to investigate the reliability of the solder joints made under various conditions. The process variables studied include solder pad diameters, solder paste volume and reflow peak temperatures. Findings - The average joint diameter increased with the peak reflow temperature, stencil thickness and pad diameter. The average joint height decreased with the increasing peak reflow temperature and pad diameter. However, increased stencil thickness would lead to increased solder paste volume and therefore increases both joint diameter and height. The assembled boards were subjected to a temperature cycling test (-40 to +125°C) for 5,700 cycles and no failures of the daisy chained resistance loops were found, indicating that the thermal fatigue resistance of the SnAgCu solder joints was good. Originality/value - The findings provide greater confidence to implement a lead-free soldering process without compromising reliability. Reliable lead free soldering can be made over a wide process window allowing flexibility in design and manufacturing.

Notes: Purpose - Anisotropic conductive film (ACF) is now an attractive technology for direct mounting of chips onto the substrate as an alternative to lead-free solders. However, despite its various advantages over other technologies, it also has many unresolved reliability issues. For instance, the performance of ACF assembly in high temperature applications is questionable. The purpose of this paper is to study the effect of bonding temperatures on the curing of ACFs, and their mechanical and electrical performance after high temperature ageing. Design/methodology/approach - In the work presented in this paper, the curing degree of an ACF at different bonding temperatures was measured using a differential scanning calorimeter. The adhesion strength and the contact resistance of ACF bonded chip-on-flex assembly were measured before and after thermal ageing and the results were correlated with the curing degree of ACF. The ACF was an epoxy-based adhesive in which Au-Ni coated polymer particles were randomly dispersed. Findings - The results showed that higher bonding temperatures had resulted in better ACF curing and stronger adhesion. After ageing, the adhesion strength increased for the samples bonded at lower temperatures and decreased for the samples bonded at higher temperatures. ACF assemblies with higher degrees of curing showed smaller increases in contact resistance after ageing. Conduction gaps at the bump-particle and/or particle-pad interfaces were found with the help of scanning electron microscopy and are thought to be the root cause of the increase in contact resistance. Originality/value - The present study focuses on the effect of bonding temperatures on the curing of ACFs, and their adhesion strength and electrical performances after high temperature ageing. The results of this study may help the development of ACFs with higher heat resistance, so that ACFs can be considered as an alternative to lead-free solders.

Notes: Purpose - This paper reports on the development of a method for the prediction of clothing pressure of girdles on the human body. Design/methodology/approach - In this paper, we propose to use a standard mannequin dummy to measure the clothing pressure of girdles and from which to predict the pressure on the different human body. An improved mathematical programming method for numerical simulation of cloth wrinkling is investigated. Findings - In general, the prediction equations of the model are effective in estimating the clothing pressure on the human body from the clothing pressure on a standard mannequin dummy. Practical implications - The method may be used by the manufacturers of girdles to test their products on a dummy to see whether the pressure distribution is satisfactory to the targeted group of consumers. It can also be used by consumers to assess the suitability of girdles based on the estimated clothing pressure, which may be predicted from the pressure pre-tested on a dummy and the consumer's body characteristics. Originality/value - Direct measurement of clothing pressure on human body for the evaluation of pressure garments is time consuming, expensive. It is therefore desirable to predict the girdle's pressure instead of the direct measurement on human subjects. The method may be used by manufacturers of girdles as well as by consumers.

Notes: Purpose - This paper proposes a simplified two-dimensional representation of the unit cell of the fabric that involves three bodies in contact. Design/methodology/approach - The fabrics are not simple homogenous structures. They have a discrete structural character and this is essential for their complex mechanical behaviour. Low stress micro-mechanics is mainly used for the prediction of the fabric hand. Modelling of the fabric microstructure is a powerful tool for the in-depth study of their performance. Based on the geometrical models of the fabrics, finite element analysis (FEA) is a very useful method for the mechanical analysis of their complex shape structures. Especially FEA can be applied on a system of bodies in contact by taking into account the interactions between the individual bodies. The parametric FEA analysis of the unit cell of the fabric provides interesting results about its mechanical behaviour. Findings - The present work states that the use of the finite element method is a friendly and convenient method for an in-depth study of the contact phenomena, which are dominating on the total mechanical behaviour of the fabrics. Originality/value - This paper provides a simplified two-dimensional representation of a unit cell of a fabric that involves three bodies in contact. The parametric FEA analysis of the unit cell of the fabric provides interesting results.

Notes: Purpose - The paper discusses the prediction of shirt patterns for different body sizes using multiple linear regression (MLR).Design/methodology/approach - A total of 29 pattern parameters from men's tailor-made shirt and 34 body parameters obtained from a body scanner were designed for analysis. MLR has been applied to examine the underlying relationship between shirt pattern parameters and body measurements.Findings– Compared with formulae from the pattern expert, the prediction of shirt pattern from MLR has been improved.Originality/value - The findings could help to predict pattern size with different body sizes more accurately.

Notes: Purpose - In order to mass-customize clothes, it is essential to consider individual body shape using computerized 3D body models. This paper describes the development of an interactive body model that can be altered with individual body shape for the purpose of computerized pattern making.Design/methodology/approach - For altering perimeter and length for contouring individual body shapes, a cross-sectional line model is proposed arranged at regular intervals. This model is easy for controlling body shape and also for calculating length and perimeters. Shape control lines (SCL) are used to modify the shape of the model in order to adjust the model to represent different body shapes. SCL are used to modify the perimeter of the cross-sectional line by scaling method with different center position and scaling ratio in a horizontal direction.Findings - In order to investigate whether virtual body models can be adequately substituted for real physical models, the perimeter and cross-section areas of shape control lines were compared, which resulted in an agreement ratio of over 93 percent. This fact supports the adaptability and potential usefulness of the body model.Originality/value - This research makes it possible for customers to modify the body model to match their own body shape during internet or catalogue shopping; it can also enable apparel manufacturers to communicate with their customers by describing the body model to fit on the screen while in the ordering process.

Notes: Purpose - The dependence of seam slippage values on fabric construction parameters makes this property an interesting case for study. Design/methodology/approach - In this study, made on a significant wool and blended fabrics sample, the seam slippage was measured, either in warp direction (weft yarns slip), or in weft direction (warp yarns slip), using a specially equipped load-elongation tester. Testing was done following the TM 117 Woolmark Company test method. Findings - For most fabrics, the conventional variables that impact seam slippage most seriously are opacity, polyamide content, finish type and cover factor. Research limitations/implications - Since this research does not deal with the variable of yarn crimp in fabrics, it is the cover factor that plays the central role, as the property determining seam slippage. The yarns with lower cover factor (less crimped) are in less danger of slipping between the perpendicular yarns (more crimped) and vice versa. Practical implications - Based on the equations given, and changing the most relevant variables concerning the explanation of the fabric seam slippage property, the fabric properties can be optimised for specific end-uses. Originality/value - Optimisation of seam slippage in fabric design.

Notes: Purpose - To design, develop and construct specific garment designs for use in Croatia as academic gowns using advanced engineering principles. Design/methodology/approach - The synergism of historians, designers, engineers, clothing technologists and textile finishers using specialised equipment has been employed in this project. Findings - Using interdisciplinarity can yield good results. Research limitations/implications - The research targets specific products, but its methodology may be used for any other products/end users also. Practical implications - Gowns have been designed, made and used in academic ceremonies successfully. Originality/value - Design/technology approach to new product development.

Notes: Purpose - The equipment for computerised measuring of electrical power and energy is presented, adapted to the needs of investigating processing parameters of garment sewing operations. Design/methodology/approach - The method of measuring the energy necessary to run the sewing-machine driving electrical motor is also presented, correlated to the stitching speed in joining a straight seam in a single, two, or three, segments. Electrical energy consumption is analysed as dependent on the stitching speed, varying the number of stitches in the seam. Findings - The investigations described have shown the impact of the method of work applied and the effect of the changes in garment sewing operation in processing parameters on the level of electrical energy consumed by the sewing-machine drive electrical motor. A new measuring method has been introduced in garment engineering, aimed at predicting electrical energy consumption in garment sewing operations, thus opening a completely new field of investigation in the area of garment technologies. Originality/value - A method of calculating the energy processing parameters of sewing operations.

Notes: Purpose - The purpose of this paper is to investigate and illustrate the possibilities of a systematic engineering approach in the design of mechanical reinforcements in garments. A mechanical reinforcement can be designed using optimisation strategies. Design/methodology/approach - In this work, an iterative algorithm for minimum search based on parabolic approximations is proposed and applied in the optimisation of mechanical reinforcement in a selected model problem of a buttonhole type. Findings - Optimisation algorithm based on parabolic approximations, in conjunction with the finite element analysis, offers some promising possibilities as support for the decision-making process in the design of mechanical reinforcements. The selection of optimisation criteria - influence parameters and corresponding weight factors - remains of course to be studied and implemented by the clothing engineering experts. Research limitations/implications - The intention in future work should be to optimise two or more geometric parameters simultaneously (multidimensional optimisation), and to produce a computer program for an automated optimum search. Practical implications - The contents of the paper could be useful for the experts in clothing engineering in the process of design or selection of the reinforcements of weak spots in textiles and garments. Originality/value - This paper provides optimisation routes to the weak sports of mechanical reinforcements in textiles and garments.

Notes: Purpose - To provide modeling approaches of increasing levels of complexity for the analysis of convective heat transfer in microchannels which offer adequate descriptions of the thermal performance, while allowing easier manipulation of microchannel geometries for the purpose of design optimization of microchannel heat sinks. Design/methodology/approach - A detailed computational fluid dynamics model is first used to obtain baseline results against which five approximate analytical approaches are compared. These approaches include a 1D resistance model, a fin approach, two fin-liquid coupled models, and a porous medium approach. A modified thermal boundary condition is proposed to correctly characterize the heat flux distribution. Findings - The results obtained demonstrate that the models developed offer sufficiently accurate predictions for practical designs, while at the same time being quite straightforward to use. Research limitations/implications - The analysis is based on a single microchannel, while in a practical microchannel heat sink, multiple channels are employed in parallel. Therefore, the optimization should take into account the impact of inlet/outlet headers. Also, a prescribed pumping power may be used as the design constraint, instead of pressure head. Practical implications - Very useful design methodologies for practical design of microchannel heat sinks. Originality/value - Closed-form solutions from five analytical models are derived in a format that can be easily implemented in optimization procedures for minimizing the thermal resistance of microchannel heat sinks.

Notes: Purpose - To determine the optimal dimensions for a stacked micro-channel using the genetic algorithms (GAs) under different flow constraints. Design/methodology/approach - GA is used as an optimization tool for optimizing the thermal resistance of a stacked micro-channel under different flow constraints obtained by using the one dimensional (1D) and two dimensional (2D) finite element methods (FEM) and by thermal resistance network model as well (proposed by earlier researcher). The 2D FEM is used to study the effect of two dimensional heat conduction in the micro-channel material. Some parametric studies are carried out to determine the resulting performance of the stacked micro-channel. Different number of layers of the stacked micro-channel is also investigated to study its effect on the minimum thermal resistance. Findings - The results obtained from the 1D FEM analysis compare well with those obtained from the thermal resistance network model. However, the 2D FEM analysis results in lower thermal resistance and, therefore, the importance of considering the conduction in two dimensions in the micro-channel is highlighted. Research limitations/implication - The analysis is valid for constant properties fluid and for steady-state conditions. The top-most surfaces as well as the side surfaces of the micro-channel are considered adiabatic. Practical implications - The method is very useful for practical design of micro-channel heat-sinks. Originality/value - FEM analyses of stacked micro-channel can be easily implemented in the optimization procedure for obtaining the dimensions of the stacked micro-channel heat-sinks for minimum thermal resistance.

Notes: Purpose - To analyze two-phase flow in micro-channel heat exchangers used for high flux micro-electronics cooling and to obtain performance parameters such as thermal resistance, pressure drop, etc. Both uniform and non-uniform micro-channel base heat fluxes are considered. Design/methodology/approach - Energy balance equations are developed for two-phase flow in micro-channels and are solved using the finite element method (FEM). A unique ten noded element is used for the channel descritization. The formulation also automatically takes care of single-phase flow in the micro-channel. Findings - Micro-channel wall temperature distribution, thermal resistance and the pressure drop for various uniform micro-channel base heat fluxes are obtained, both for single- and two-phase flows in the micro-channel. Results are compared against data available in the literature. The wall temperature distribution for a particular case of non-uniform base heat flux is also obtained. Research limitations/implications - The analysis is done for a single micro-channel and the effects of multiple or stacked channels are not considered. The analysis needs to be carried out for higher heat fluxes and the validity of the correlation needs to be ascertained through experimentation. Effects of flow mal-distribution in multiple channels, etc. need to be considered. Practical implications - The role of two-phase flow in micro-channels for high flux micro-electronics cooling in reducing the thermal resistance is demonstrated. The formulation is very useful for the thermal design and management of microchannels with both single- and two-phase flows for either uniform or non-uniform base heat flux. Originality/value - A simple approach to accurately determine the thermal resistance in micro-channels with two-phase flow, for both uniform and non-uniform base heat fluxes is the originality of the paper.

Notes: Purpose - To numerically model forced convection heat transfer over arrays of solder balls. Design/methodology/approach - The characteristic based split (CBS) scheme has been used to solve the incompressible Navier-Stokes equations on unstructured meshes. Findings - The results show an increase in heat transport with increase in Reynolds numbers. A significant change in heat transfer is also noticed with change in angle of attack. Originality/value - The presented results will be useful in designing cooling systems for electronic components.

Notes: Purpose - To provide some new and additional data for the design of a triple stack cold plate. Design/methodology/approach - A detailed finite element formulation for the triple stack cold plate with and without heat losses from the top and bottom surfaces of the stack is presented to determine its performance under steady as well as unsteady conditions. The effects of the number of unit cells, different heat losses as well as the governing dimensionless parameter, M (involving stack dimension, properties of the stack material and the variation in the heat transfer coefficient) on the performance of the stack are investigated. The detailed formulation of the asymptotic waveform evaluation scheme is also given and applied to determine the transient performance of the stack. Findings - The methods of analysis described are quite simple to use to determine the steady and unsteady performance of the triple stack cold plate under different operating conditions. The heat losses from the top and bottom surfaces of the stack do affect the maximum temperature of the stack and in such case, the assembled stack should be analysed. Research limitations/implications - The analysis is limited to an incompressible fluid. The effect of varying mass flow rate of the fluid in the stack passages is also not considered. Practical implications - New and additional generated data will be helpful in the design of cold plates used in the cooling of electronic components. Originality/value - The asymptotic waveform evaluation scheme is used for the first time to determine the transient performance of the triple stack cold plate under different operating conditions. The results thus obtained are compared well with those found from the finite element analysis (FEM), but the computational effort and time required in the analysis is much small as compared to those required in the FEM analysis.

Notes: Purpose - In the semiconductor electronics industry, effective heat removal from the integrated circuits (IC) chip, through the electronic package to the environment is crucial to maintain an allowable junction temperature of the IC chip. Thermal performances of such electronic packages are characterized by package thermal resistance called -JA and are widely used in the electronic industry. Improving thermal performance is numerically predicted using computational fluid dynamics (CFD) technique and experimental tests are carried out to verify the numerical predictions. To provide new/additional data and demonstrate CFD technique for thermal characterization of electronic packages with experimental results. Design/methodology/approach - The thermal performance of electronic packages has been studied using a CFD technique. The finite volume method is a technique used for solving a set of partial differential equations in a domain, using control volume based discretization. A detailed thermal model of an electronic package was created using a CFD tool and validated against the experimental data obtained in a natural convection environment, compliant to JEDEC standards. The thermal performance of the package was evaluated for different die sizes and epoxy molding compounds at different power levels. The use of a heat slug was investigated to identify its effect on heat dissipation for the future generations of IC, which are expected to be smaller in size and to dissipate more power. Free convective flow velocities, detailed temperature and heat flow distributions around the package will also be presented. Findings - The study demonstrates that applying CFD techniques can provide accurate results on estimating thermal characterization of an electronic package. Predicted device junction temperatures as well as the thermal resistance of packages can be predicted with a good accuracy for different ranges of power levels in natural convection. The numerically estimated die junction temperatures have also been found to be accurate and reliable. Research limitations/implications - The analysis is limited to an incompressible fluid. The effect of forced convection is not considered. Practical implications - New and additional generated data will be helpful in the design and decision making time of the product to choose a low cost and viable thermal performance solution in the cooling of electronic components at low power. Originality/value - The electronic package involves multi-material and applying CFD technique is useful to determine the accurate thermal performance and simple and fast to apply for different conditions/material sets. Predictions of junction-to-ambient thermal resistance and device junction temperature values are compared against measurements. Excellent correlation was obtained. The results thus obtained compare well with the experimental results, but the computational effort and time required in the analysis is much small as compared.

Notes: Purpose - The present paper addresses the computer modelling of pipe formation in metal castings. Design/methodology/approach - As a preliminary, a brief review of the current state-of-the-art in pipe shrinkage computation is presented. Then, in first part, the constitutive equations that have to be considered in thermomechanical computations are presented, followed by the main lines of the mechanical finite element resolution. A detailed presentation of an original arbitrary Lagrangian-Eulerian (ALE) formulation is given, explaining the connection between the Lagrangian and the quasi Eulerian zones, and the treatment of free surfaces. Findings - Whereas most existing methods are based on thermal considerations only, it is demonstrated in the current paper that this typical evolution of the free surface, originated by shrinkage at solidification front and compensating feeding liquid flow, can be effectively approached by a thermomechanical finite element analysis. Research limitations/implications - Future work should deal with the following points: identification of thermo-physical and rheological data, automatic and adaptive mesh refinement, calculation of the coupled deformation of mold components, development of a two-phase solid/liquid formulation. Practical implications - An example of industrial application is given. The proposed method has been implemented in the commercial software THERCAST® dedicated to casting simulation. Originality/value - The proposed numerical methods provide a comprehensive approach, capable of modelling concurrently all the main phenomena participating in pipe formation.

Notes: Purpose - In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. Erosion in the tube entrance region of a typical shell and tube heat exchanger is numerically predicted. Design/methodology/approach - The erosion rates are obtained for different flow rates and particle sizes assuming low particle concentration. The erosion prediction is based on using a mathematical model for simulating the fluid velocity field and another model for simulating the motion of solid particles. The fluid velocity (continuous phase) model is based on the solution of the time-averaged governing equations of 3D turbulent flow while the particle-tracking model is based on the solution of the governing equation of each particle motion taking into consideration the viscous and gravity forces as well as the effect of particle rebound behavior. Findings - The results show that the location and number of eroded tubes depend mainly on the particle size and velocity magnitude at the header inlet. The rate of erosion depends exponentially on the velocity. The particle size shows negligible effect on the erosion rate at high velocity values and the large-size particles show less erosion rates compared to the small-size particles at low values of inlet flow velocities. Originality/value - In oil and gas industries, the presence of sand particles in produced oil and natural gas represents a major concern because of the associated erosive wear occurring in various flow passages. The results indicate that erosion in shell and tube heat exchanger can be minimized through the control of velocity inlet to the header.

Notes: Purpose - Obtaining the maximum possible flow rates that can be induced by free convection in open-ended vertical eccentric annuli under fundamental thermal boundary conditions of the fourth kind (heating or cooling one of the annulus walls with a uniform heat flux while keeping the other wall at ambient temperature). Obtaining the maximum possible flow rates that can be induced by free convection in open-ended vertical eccentric annuli under fundamental thermal boundary conditions of the fourth kind (heating or cooling one of the annulus walls with a uniform heat flux while keeping the other wall at ambient temperature). Design/methodology/approach - The fully-developed laminar free convection momentum equation has been solved numerically using an analytical solution of the governing energy equation. Findings - Results are presented to show the effect of the annulus radius ratio and the dimensionless eccentricity on the induced flow rate, the total heat absorbed by the fluid, and the fully developed Nusselt numbers on the two boundaries of the annulus for a fluid of Prandtl number 0.7. Practical implications - Applications of the obtained results can be of value in the heat-exchanger industry, in cooling of underground electric cables, and in cooling small vertical electric motors and generators. Originality/value - The paper presents a solution that is not available in the literature for the problem of fully developed free convection in open-ended vertical eccentric annular channels under thermal boundary conditions of the fourth kind. Also presents the maximum possible induced flow rates, the total heat absorbed by the fluid, and the Nusselt numbers on the two boundaries of the annulus. The effects of N and E (the radius ratio and eccentricity, respectively) on these results are presented. Such results are very much needed for design purposes of heat transfer equipment.

Notes: Purpose - To address the impact of adding insulated plate extensions at the entrance of an isoflux vertical parallel-plate channel on the thermal performances of natural convection in air for these systems. Design/methodology/approach - The model relies on the full elliptic conservation equations which are solved numerically in a composite three-part computational domain by means of the finite-volume method. Findings - Results are reported in terms of wall temperatures, induced mass flow rates, as well as velocity and temperature profiles of the air for various thermal and geometric parameters. The wall temperatures increase when the extensions are appended at the inlet of the channel. Wall temperature profiles strongly depend on the Rayleigh number and the dependence of the heated channel aspect ratio is weaker than the extension ratio. Velocity and temperature profiles modify inside the heated channel due to the thermal development. In addition, correlation equations for main engineering quantities, such as the induced mass flow rate, average Nusselt number and dimensionless maximum wall temperature in terms of the channel Rayleigh number, channel aspect ratio and extension ratio are presented. Research limitations/implications - The investigation has been carried out in the following ranges: 103-105 for the Rayleigh number, 5.0-15.0 for the channel aspect ratio and 1.0-5.0 for the extension ratio. The hypotheses on which the present analysis is based are: two-dimensional, laminar and steady-state flow, constant thermophysical properties with the Boussinesq approximation. Practical implications - Thermal design of heating systems in manufacturing processes, evaluation of heat convective coefficients and maximum attained wall temperatures. Originality/value - Evaluation of the thermal and velocity fields and correlation equations for the Nusselt number and maximum dimensionless temperatures in natural convection in air for vertical channels. The paper is useful to thermal designers.

Notes: Purpose - To investigate the heat transfer enhancement performed by installing a rectangular plate turbulator for internal flow modification induced by vortex shedding. Design/methodology/approach - The large eddy simulation (LES) and SIMPLE-C method coupled with preconditioned conjugate gradient methods have been applied to the turbulent flow field and heat transfer enhancement of mixed convection in a block-heated channel. Findings - Provides information about heat transfer performance indicating that heat transfer performance can be affected by various width-to-height ratio of turbulator and Grasehof numbers with a constant Reynolds number. The results show that the installation of turbulator in cross-flow above an upstream block can effectively enhance the heat transfer performance by suitable width-to-height ratio of turbulator and Grasehof numbers. Research limitations/implications - It is limited to two-dimensional mean flow for the turbulent vortex-shedding flow past a long square cylinder. Practical implications - A very useful source of information and favorable advice for people developing heat transfer enhancement for electronic devices. Originality/value - The results of this study may be of interest to engineers attempting to develop thermal control of electronic devices and to researchers interested in the turbulent flow-modification aspects of heat transfer enhancement of mixed convection in a vertical channel.

Notes: Purpose - A computational fluid dynamics code for the calculation of laminar hypersonic multi-species gas flows in chemical non-equilibrium in axisymmetric or two-dimensional configuration on shared and distributed memory parallel computers is presented and validated. The code is designed to work efficiently in combination with an automatic domain decompositioning method developed to facilitate efficient parallel computations of various flow problems. Design/methodology/approach - The baseline implicit numerical method developed is the lower-upper symmetric Gauss-Seidel scheme, which is combined with a sub-iteration scheme to achieve time-accuracy up to third-order. The spatial discretisation is based on Roe's flux-difference splitting and various non-linear flux limiters maintaining total-variation diminishing properties and up to third-order spatial accuracy in continuous regions of flow. The domain subdivision procedure is designed to work for single- and multi-block domains without being constrained by the block boundaries, and an arbitrary number of processors used for the computation. Findings - The code developed reproduces accurately various types of flows, e.g. flow over a flat plate, diffusive mixing and oscillating shock induced combustion around a projectile fired into premixed gas, and demonstrates close to linear scalability within limits of load imbalance. Research limitations/implications - The cases considered are axisymmetric or two-dimensional, and assume laminar flow. An extension to three-dimensional turbulent flows is left for future work. Originality/value - Results of a parallel computation, utilising a newly developed automatic domain subdivision procedure, for oscillating shock-induced combustion around a projectile and various other cases are presented. The influence of entropy correction in Roe's flux-difference splitting algorithm on diffusive mixing of multi-species flows was examined.

Notes: Purpose - To provide a finite volume code, based on Cartesian coordinates, for studying combined conductive and radiative heat transfer in three-dimensional irregular geometries. Design/methodology/approach - In the present study, a three-dimensional blocked-off-region procedure was presented and implemented in a numerical code based on the finite volume method to model combined conductive and radiative heat transfer in complex geometries. This formulation was developed and tested in three-dimensional complex enclosures with diffuse reflective surfaces and containing gray absorbing-emitting and isotropically scattering medium. This approach was applied to analyze the effect of the main of thermoradiative parameters on the temperature and flux values for three-dimensional L-shaped enclosure. Findings - The proposed isotropic model leads to satisfactory solutions with comparison to reference data, which entitles us to extend it to anisotropic diffusion cases or to non-gray media. The blocked-off-region procedure traits both straight and curvilinear boundaries. For curved or inclined boundaries, a fine or a non-uniform grid is needed. Originality/value - This paper offers a simple Cartesian practical technique to study the combined conductive and radiative heat transfer in three-dimensional complex enclosures with both straight and curvilinear boundaries.

Notes: Purpose - The aim of this work is to determine the optimal number and location of the fin(s) for maximum laminar forced convection heat transfer from a cylinder with multiple high conductivity radial fins on its outer surface in cross-flow, i.e. Nusselt number, over a range of Reynolds numbers. Design/methodology/approach - The effect of several combinations of number of fins, fin height, and fin(s) tangential location on the average Nusselt number was studied over the range of Reynolds numbers (5-150). The problem was investigated numerically using finite difference method over a stretched grid. The optimal number and placement of the fins, for maximum Nusselt number, was determined for several combinations of Reynolds number and fin height. The percentage improvement in heat transfer per fin(s) unit length, i.e. cost-efficiency, was also studied. Findings - The results indicate that the fin(s) combination with the highest normalised Nusselt number is not necessarily the combination that results in the highest fin cost-efficiency. Originality/value - The results of the study can be used to design highly efficient cross-flow forced convection heat transfer configurations from a horizontal cylinder with minimum cost.

Notes: Purpose - The transient hydrodynamics and thermal behavior of free convection flow over an isothermal vertical flat plate is investigated. Design/methodology/approach - The study focuses on the role of the local acceleration term in the magnetohydrodynamic (MHD) momentum equation. A finite difference method based on a second-order differential equation is used to solve the differential equations. Findings - It is found that the local acceleration term has insignificant effect on the flow behavior especially at large values of magnetic forces. Also, it is found that the effect of the magnetic forces on the flow hydrodynamics behavior is significant but its effect on the thermal behavior is insignificant. It has been realized that the local acceleration term is usually small compared to the magnetic retarding force, and hence can be neglected. Research limitations/implications - A quantitative description of the operating and geometrical parameters within which the local acceleration term may be significant is not available in the literature yet. Also, the authors' intention is to improve physical understanding of the hydrodynamic and thermal behaviors of the present problem. Originality/value - The study provides results concerning the thermal behavior of free convection flow.

Notes: Purpose - This paper presents a new numerical model that, unlike most existing ones, can solve the whole liquid sloshing, nonlinear, moving boundary problem with free surface undergoing small to very large deformations without imposing any linearization assumptions. Design/methodology/approach - The time-dependent, unknown, irregular physical domain is mapped onto a rectangular computational domain. The explicit form of the mapping function is unknown and is determined as part of the solution. Temporal discretization is based on one-step implicit method. Second-order, finite-difference approximations are used for spatial discretizations. Findings - The performance of the algorithm has been verified through convergence tests. Comparison between numerical and experimental results has indicated that the algorithm can accurately predict the sloshing motion of the liquid undergoing large interfacial deformations. Originality/value - The ability to model liquid sloshing motion under conditions leading to large interfacial deformations utilizing the model presented in this paper improves our ability to understand the problem of sloshing motion in tuned liquid dampers (TLDs), which would eventually help in constructing more effective TLDs.

Notes: Purpose - Corrosion in deadlegs occurs as a result of water separation due to the very low flow velocity. The present work aims to investigate the effect of geometry on flow field oil/water separation in deadlegs in an attempt for obtaining the conditions for avoiding formation of deadleg. Design/methodology/approach - The investigation is based on the solution of the mass and momentum conservation equations of an oil/water mixture together with the volume fraction equation for the secondary phase. A fluid flow model based on the time-averaged governing equation of 3D turbulent flow has been developed. An algebraic slip mixture model for the calculation of the two immiscible fluids (water and crude oil) is utilized. Findings - Results are obtained for different lengths of the deadleg. The inlet flow velocity is kept unchanged (1.0?m/s) and the deadleg length to diamter ratio (L/DB) ranges from 1 to 7. The considered fluid mixture contains 90 percent oil and 10 percent water (by volume). The results show that the size of the stagnant fluid region increases with the increase of L/DB 1˜3DB. Practical implications - Deadlegs should be avoided whenever possible in design of piping for fluids containing or likely to contain corrosive substance. When deadlegs are unavoidable, the length of the inactive pipe must be as short as possible to avoid stagnant or low-velocity flows. Originality/value - The model solves the continuity and momentum equations for the mixture, and the volume fraction equation for the secondary phase utilizing an algebraic expression for the relative velocity.

Notes: Purpose - To investigate numerically the settling of small solid particles in a suspension of motile gyrotactic micro-organisms in order to evaluate the possibility of using bioconvection to slow down settling and enhance mixing between particles. Design/methodology/approach - Numerical computations are performed at the North Carolina Supercomputing Center utilizing an Origin 2400 workstation. A conservative finite-difference scheme is used to discretize the governing equations. A staggered uniform grid with the stream function and vorticity stored in one set of nodes and the number densities of micro-organisms and solid particles stored in another set of nodes is utilized. CPU time required to investigate plume development until it attains steady-state for 36?×?36 uniform mesh is about 50?h. Findings - It is established that small solid particles that are heavier than water slow down bioconvection. Extremely small particles (nanoparticles) that have negligible settling velocity do not have any noticeable impact on bioconvection, very large particles (that have negligible diffusivity), or very heavy particles (that have very large settling velocity) also do not have any impact on bioconvection because they simply settle at the bottom. However, if the particles are of the optimal size and density (gravitational settling must compete with Brownian diffusion to create an exponential number density distribution of solid particles with the maximum at the bottom of the chamber), these particles can effectively slow down bioconvection. Research limitations/implications - The question how solid particles may affect the wavelengths of bioconvection patterns requires further investigation. Practical implications - The finding that solid particles slow down bioconvection may be important in using bioconvection to enhance mixing in fluid microvolumes. Originality/value - The paper provides a model and numerical data about the effect of bioconvection on mixing of small solid particles. These data are valuable for researches working in fundamental fluid mechanics, multiphase flow, and applications of bioconvection.

Notes: Purpose - To introduce a novel numerical calculation procedure for periodically fully developed heat and fluid flow, which can treat three-dimensional velocity and temperature fields, using a two-dimensional storage. Design/methodology/approach - The three-dimensional Navier-Stokes equation and energy equation have been transformed into quasi-three-dimensional forms. An appropriate set of explicit periodic boundary conditions have been obtained for thermally fully developed flow through a general three-dimensional periodic structure, exploiting the volume averaging theory. Findings - The proposed numerical procedure has been found inexpensive and efficient. Its validity has been proved by comparing the results obtained for a bank of long cylinders in yaw against available experimental data. Originality/value - Since no explicit sets of periodic boundary conditions of this kind have been reported before, they will be exploited by researchers and practitioners interested in efficient numerical computations of three-dimensional periodic heat and fluid flows.

Notes: Purpose - To investigate the influence of conical and annular nozzle geometric configurations on the flow structure and heat transfer characteristics near the stagnation point of a flat plate with limited heated area. Design/methodology/approach - The conical and annular conical nozzles were designed such that the exit area of both nozzles is the same and the mass flow rate passing through the nozzles is kept constant for both nozzles. The governing equations of flow and heat transfer are modeled numerically using a control volume approach. The grid independent solutions are secured and the predictions of flow and heat transfer characteristics are compared with the simple pipe flow with the same area and mass flow rate. The Reynolds stress turbulence model is employed to account for the turbulence. A flat plate with a limited heated area is accommodated to resemble the laser heating situations and air is used as assisting gas. Findings - It is found that nozzle exiting velocity profiles differ considerably with changing the nozzle cone angle. Increasing nozzle cone angle enhances the radial flow and extends the stagnation zone away from the plate surface. The impinging jet with a fully developed velocity profile results in enhanced radial acceleration of the flow. Moreover, the flow structure changes considerably for annular conical and conical nozzles. The nozzle exiting velocity profile results in improved heat transfer coefficient at the flat plate surface. However, the achievement of fully developed pipe flow like velocity profile emanating from a nozzle is almost impossible for practical laser applications. Therefore, use of annular conical nozzles facilitates the high cooling rates from the surface during laser heating process Research limitations/implications - The results are limited with theoretical predictions due to the difficulties arising in experimental studies. Practical implications - The results can be used in laser machining applications to improve the end product quality. It also enables selection of the appropriate nozzle geometry for a particular machining application. Originality/value - This paper provides information on the flow and heat transfer characteristics associated with the nozzle geometric configurations and offers practical help for the researchers and scientists working in the laser machining area.

Notes: Purpose - To improve inviscid compressible flow solution. Design/methodology/approach - A local element-size calculation procedure in the streamline direction and a local variable smoothing approach are employed to improve inviscid compressible flow solution. The characteristic based split approach is used as basic solution procedure to demonstrate the employed improvements. Findings - Results show that employing the element size in the streamline direction improves the solution accuracy in the transonic flow region. The nodal variable smoothing is very effective below a Mach number of 0.85 and produces results without any spatial oscillations. Originality/value - This paper fills the gap by suggesting novel procedures to study Mach number range between zero and supersonic flow.

Notes: Purpose - The objective of the research work is to predict the volume of fluid drained from a cylindrical vessel without entrapping air through the drainpipe, and hence predict the location of the free surface of the liquid in the vessel. Design/methodology/approach - A two-dimensional axi-symmetric numerical simulation has been made using a finite volume method that employs unstructured grids with cell-wise local refinement and an interface capturing scheme to predict the shape of the free surface of water in a cylindrical vessel, thus simulating the entrapment of air in the drainpipe connected to the vessel. Findings - A drain cover was placed on top of the drainpipe to delay the entry of air into the drainpipe. It was found that an increase in the diameter of the drain cover increases the amount of liquid to be drained out before the air could enter into the drainpipe. It was found that air enters the drainpipe at a particular height of the liquid in the vessel. However, when an initial rotational velocity was imparted to the liquid, the height of liquid when air enters the drainpipe depends on the initial bath height. As the initial bath height increases, air enters the drainpipe at a progressively higher bath height. But surprisingly when the drain cover is put in place the initial bath height, again, has no effect on the height of the liquid (in the vessel). Practical implications - The outcome of the present research work has direct implications for steel making. If the drainpipe can be connected to the ladle the way it has been discussed in this paper then more steel can be drained before stopping the drainage in order to avoid air or slag entrapment. Originality/value - The idea of putting a drain cover, using a larger diameter drainpipe and making the drainpipe connection to the vessel different so as to delay the appearance of air at the drainpipe is a new finding and the idea can be used by steel makers.

Notes: Purpose - To highlight the effect of viscous and Joule heating on different ionized gases in the presence of magneto and thermal radiation effects. Design/methodology/approach - The conservation equations are written for the MHD forced convection in the presence of thermal radiation. The governing equations are transformed into non-similar form using a set of dimensionless variables and then solved numerically using Keller box method. Findings - The increasing of fluid suction parameter enhances local Nusselt numbers, while the increasing of injection parameter decreases local Nusselt numbers. The inclusion of thermal radiation increases the heat transfer rate for both ionized gases suction or injection. The presence of magnetic field decreases the heat transfer rate for the suction case and increases it for the injection case. Finally, the heat transfer rate is decreased due to viscous dissipation. Research limitations/implications - The combined effects of both viscous and Joule heating on the forced convection heat transfer of ionized gases for constant surface heat flux surfaces can be investigated. Practical implications - A very useful source of coefficient of heat transfer values for engineers planning to transfer heat by using ionized gases. Originality/value - The viscous and Joule heating of ionized gases on forced convection heat transfer in the presence of magneto and thermal radiation effects are investigated and can be used by different engineers working on industry.