Zinc-based Alloy Research Articles

An investigation of lubricated friction and wear properties of Zn–40Al–2Cu–2Si alloy in comparison with SAE 65 bearing bronze

In this study, friction and wear characteristics of Zn–40Al–2Cu–2Si alloy were investigated in both as cast and heat-treated conditions over a range of pressure and sliding speed and the results were compared with those obtained from SAE 65 bearing bronze. The heat treatment was performed by solutionizing and quench ageing. It was found that the friction coefficients of both zinc-based alloy and bronze decreased with increasing pressure and sliding speed but their temperatures increased with these parameters. It was also found that the wear loss of the zinc-based alloy and the bronze increased with increasing pressure and sliding speed. The zinc-based alloy in both as cast and heat-treated conditions exhibited much higher wear resistance than the SAE 65 bronze, especially at pressures above 4 MPa. It was also observed that the quench-ageing treatment increased the hardness and the tensile strength of Zn–40Al–2Cu–2Si alloy considerably, but only a small improvement was obtained in the wear resistance of the alloy after this heat treatment.

Microstructural and sliding wear behaviour of a heat-treated zinc-based alloy

The effect of heat treatment on microstructure, hardness, tensile properties, fracture mode and wear behaviour during lubricated and dry sliding of the zinc-based alloy with 25 wt.%Al was studied. Microstructural investigation and chemical analysis of as-cast and heat-treated specimens, the fracture and worn surfaces, as well as wear debris were performed by scanning electron microscopy and energy dispersive spectroscopy. Wear tests were carried out using a disc-on block-type wear machine. By a relatively simple heat treating consisting of a short-term annealing in the single-phase region followed by water-quenching, the elongation has been markedly improved, while the strength was maintained high. The results indicate that the wear rate strongly depends on the microstructure, applied load and sliding conditions. The wear rate increases with load, and under dry sliding conditions the wear rate is approximately two orders of a magnitude higher than under lubricated conditions. During dry sliding the best wear behaviour was displayed by the water-quenched specimens, whereas slowly cooled specimens showed the higher wear rate. Lubrication strongly affects the wear behaviour. Contrary to dry sliding, slowly cooled specimens exhibit the best wear properties under lubricated conditions. The wear mechanisms were proposed for dry and lubricated sliding.

The influence of alumina particle dispersion and test parameters on dry sliding wear behaviour of zinc-based alloy

The present investigation deals with dry sliding wear characteristics of a zinc-based alloy (ZA 37) with and without Al 2O 3 particle dispersion over a range of sliding speeds and applied pressures. The matrix alloy has been examined under identical test conditions in order to examine the role played by the second phase alumina particles on wear behaviour. The observed wear behaviour of the samples has been explained in terms of specific characteristics like cracking tendency, lubricating, load bearing and deformability characteristics, and thermal stability of various microconstituents. The nature of predominance of one set of parameters (causing higher wear rate) over the other (producing a reverse effect) was thought to actually control the wear behaviour. Examinations of the characteristic of wear surfaces and subsurface regions also enabled to understand the operating wear mechanism and to substantiate the wear behaviour. At low sliding speed, significantly lower wear rate of the matrix alloy over that of the composite was noticed. This has been attributed to increased microcracking tendency of the composite than the matrix alloy. Reduced wear rate and higher seizure pressure experienced by the composite over that of the matrix alloy at the higher sliding speeds could be explained to be due to enhanced compatibility of matrix alloy with dispersoid phase and greater thermal stability of the composite in view of the presence of the dispersoid. The maximum temperature rise due to frictional heating has been observed to be low in the case of matrix alloy than composite at low speed while the trend reversed at higher speeds. In general, the wear rate and temperature increased with applied pressure and speed. Seizure pressure reduced with increasing speed while the seizure resistance (pressure) of the matrix alloy was more adversely affected by speed than that of the composite.

Dry sliding wear response of zinc-based alloy over a range of test speeds and loads: a comparative study with cast iron

This study pertains to the observations made during the sliding wear response of a zinc-based alloy in different test conditions. The effects of sliding speed and load on the wear behaviour of the alloy have been studied. The properties evaluated were wear rate, frictional heating and coefficient of friction. The wear performance of the zinc-based alloy has been compared with that of a conventional cast iron in identical test conditions. The wear rate of the samples increased with applied load and sliding speed while the seizure resistance (load) deteriorated with speed. The zinc-based alloy exhibited less wear rate and reduced frictional heating than that of the cast iron while friction coefficient followed a reverse trend. Observed wear response of the samples has been discussed in terms of specific features like lubricating, load carrying, microcracking and thermal stability of various microconstituents of the samples, and substantiated further through the features of wear surfaces, subsurface regions and debris.

Microstructural and sliding wear behaviour of a heat-treated zinc-based alloy

Microstructural and sliding wear behaviour of a heat-treated zinc-based alloy

Reactive brazing of Al alloy to Mg alloy using zinc-based brazing alloy

According to the feature of Mg–Zn eutectic reaction, Al alloy was bonded to Mg alloy by contact reaction brazing using a zinc-based brazing alloy successfully. The experimental observations showed that Mg–Al intermetallic compounds were avoided for the addition of the zinc-based brazing alloy. The Mg substrate and the remanent brazing alloy were bonded with the reaction zone that formed along the zinc rich and magnesium poor interface. Only a few Mg–Zn intermetallic compounds (MgZn2) existed homogeneously in the reaction zone. The substrate and the remanent brazing alloy were bonded with a thin Al–Zn solution. The average tensile-shear strength of the final joints was a little lower than that of the zinc-based brazing alloy owning to some pores at the interface between the reaction zone and the remanent brazing alloy layer.

Bis-(2,3,4-trihydroxyphenylazo)benzidine as a reagent for the photometric determination of aluminum

The complexation of aluminum(III) with bis-(2,3,4-trihydroxyphenylazo)benzidine is studied in the presence of urotropine, phenanthroline, 2,2′-dipyridyl, and papaverine. The optimal conditions are found for complexation. The molar absorption coefficients and stability constants of the aluminum complexes are determined. The concentration range is found in which Beer’s law is obeyed. A procedure for the photometric determination of aluminum in zinc-based alloys is proposed.

Investigation into sliding wear performance of zinc-based alloy reinforced with SiC particles in dry and lubricated conditions

The objective of the present investigation was to assess the influence of SiC particle dispersion in the alloy matrix, applied load, and the presence of oil and oil plus graphite lubricants on the wear behaviour of a zinc-based alloy. Sliding wear performance of the zinc-based alloy and its composite containing SiC particles has been investigated in dry and lubricated conditions. Base oil or mixtures of the base oil with different percentages of graphite were used for creating the lubricated conditions. Results show a large improvement in wear resistance of the zinc-based alloy after reinforcement with SiC particles. The lubrication improved the wear resistance and friction behaviour of both the reinforced and base alloys. It was also observed that there exists an optimum concentration of graphite particles in the lubricant mixture that leads to the best wear performance. The composite experienced higher frictional heating and friction coefficient than the matrix alloy in all the cases except oil lubricated conditions; a mixed trend was noticed in the latter case. The wear rate and frictional heating increased with load while friction coefficient was affected in an opposite manner. Test duration influenced the frictional heating and friction coefficient of the samples in a mixed manner. Examination of worn surfaces revealed a change of predominating wear mechanisms from severe ploughing and/or abrasive wear for base alloy to delamination wear for the reinforced material under dry sliding conditions. The presence of the lubricant increased the contribution of adhesive wear component while reducing the severity of abrasion. This was attributed to the generation of more stable lubricant films on the contacting surfaces. Cross-sections of worn surfaces indicated substantial wear-induced plastic deformation, thereby suggesting adhesive wear to be a predominant wear mechanism in this study. The debris particles revealed deformed flakes and machining chips signifying the involvement of adhesion and abrasion modes of wear respectively.

Complexation of copper(II) with 3-(2-hydroxyphenylazo)pentadione-2,4

It is shown that 3-(2-hydroxyphenylazo)pentadione-2,4 (H2L) can exist in three tautomeric forms (enol-azo, keto-azo, and hydrazo). The effective atomic charges in the tautomeric forms of H2L are calculated by the Huckel MO LCAO method. The molar fractions and molar absorptivities of the tautomers at different pH are found. The complexation of copper(II) with H2L is studied by spectrophotometry. Beer’s law is obeyed for 0.51–5.12 µg/mL of copper. The assumed complex structure is given. The effect of foreign ions and masking agents on the complexation is studied. A procedure for the photometric determination of copper(II) in zinc-based alloys is proposed.

Slurry wear behavior of zinc-based alloys: influence of some material and test parameters

This investigation pertains to the analysis of slurry wear behavior of a zinc-based alloy. The effects of material composition/microstructure, slurry composition and traversal distance and speed on the response of the alloy system have been studied. Sample rotation method was adopted for testing the samples. In some cases, unexpected wear response (from conventional understanding) was observed. For example, presence of a less corroding phase like Si particles in the alloy system caused inferior wear response while increasing traversal speed led to improved wear behavior (in the liquid-only medium). Further, hard sand particles suspended in the test environment offered superior wear characteristics despite their additional erosive and abrasive damage to the samples. In the tested range (20–60 wt%) of sand concentrations in the slurry medium, the wear rate increased initially with increasing sand concentration, attained the maximum (although less than the liquid-only medium) at 40% sand and then finally followed a reversal in the trend at a still higher sand concentration of 60%. Increasing traversal speed from 4.71 to 7.02 m/s led to inferior response while the silicon containing alloy performed better than the one without the element in general in liquid plus sand slurries. The wear rate increased with traversal distance initially, attained the maximum and then decreased once again at still larger distances. The sensitivity of the rate of increase/decrease in wear rate with distance became less in the presence of suspended sand particles in the medium (electrolyte). The observed wear response of the samples has been substantiated through specific characteristics of affected surfaces. The latter also helped to understand the operating material removal mechanisms.

Effects of heat treatment on the lubricated slading wear behaviour of zinc-based alloy containing nickel under varying test conditions

Abstract This investigation presents the observations made pertaining to the lubricated slading wear response of a zinc-based alloy containing nickel over a range of applied pressures and slading speeds. Properties studied were wear rate and fractional heating. The varying wear response of the samples under different material and test conditions has been substantiated through the features of wear surfaces, subsurface regions, and debris. The role of various microconstituents in the material and their specific features have been correlated with the observed wear behaviour of the alloy in different material and test conditions. The wear rate and fractional heating increased with pressure and speed. The data plots in general comprised initially low slope followed by a higher slope at larger applied pressures. Heat-treated samples performed better than the as-cast one except at the maximum sliding speed; a reverse trend was noted in the latter case. The studq suggests the benefits of heat treatment in terms o...

Influence of alumina dispersoid and test parameters on erosive wear behaviour of a cast zinc–aluminium alloy

Observations made pertaining to the erosive wear characteristics of a cast zinc-based alloy and its composite containing 10 wt.% (corresponding to 11.2 vol.%) alumina particles have been presented in this study. Matrix alloy has also been tested under identical test conditions in order to examine the role played by second phase alumina particles on the erosive wear resistance of the matrix alloy. Eroded surfaces and subsurface regions of the specimens were also characterized to understand the operating wear mechanisms. The composite exhibited higher erosive wear resistance (inverse of erosive wear rate) than the unreinforced matrix alloy in general. Further, the wear rate increased with increasing impingement velocity as also evident from higher surface damage. Increasing angle of impingement at lower impinging velocity led to reduced erosive wear rate. On the contrary, the erosive wear rate increased initially with impingement angle, attained the peak and then decreased at still higher angles at the higher impingement velocity. The eroded surfaces showed more abrasion grooves at lower impingement angle and greater tendency of crater formation at higher angles of attack. In case of the composite, protrusion and fracture of the dispersoid phase was also noted. The composite also revealed less severe surface and subsurface damage than the matrix alloy.

Effectiveness of an externally added solid lubricant on the sliding wear response of a zinc?aluminium alloy, its composite and cast iron

The role played by an externally added solid lubricant like graphite towards controlling the sliding wear behaviour of a zinc-based alloy has been examined in this study. The influence of dispersing hard silicon carbide particles in the alloy was also investigated by testing the composite in identical test conditions. The wear performance of the zinc-based alloy and its composite was compared with that of a gray cast iron. Wear tests were performed in oil lubricated environment. Composition of the lubricant was changed by adding various quantities of graphite (particles) to the oil. The study suggests that the wear response (in terms of wear rate, frictional heating and friction coefficient) of the samples improved in the presence of suspended graphite particles in the oil lubricant. However, this improvement was noticed up to a critical content of graphite particles only and the trend reversed at still higher graphite contents. The zinc-based (matrix) alloy revealed highest wear rate. Dispersoid silicon carbide particles showed a significant improvement in the wear performance of the matrix alloy. The cast iron performed in between the matrix alloy and composite. The frictional heating and friction coefficient were the highest for the composite while the cast iron and the matrix alloy showed a mixed response. Examinations of wear surfaces, subsurface regions and debris particles helped to substantiate the observed wear response of the samples.

Sliding wear response of a zinc-based alloy and its composite and comparison with a gray cast iron: influence of external lubrication and microstructural features

The role played by an external lubricant and features of various material microconstituents towards controlling the wear behaviour of a zinc-based alloy reinforced with silicon carbide particles has been studied under varying load conditions, in this investigation. Testing the zinc-based matrix alloy under identical conditions enabled to assess the effect of the reinforcement particles on the wear characteristics of the alloy. The wear response of the samples was compared with that of a gray cast iron. In order to study the influence of the external lubricant, dry wear tests were also conducted on the materials. The study shows that the reinforcement of SiC particles substantially affected the wear response of the zinc-based alloy. The applied load and test duration influenced the wear characteristics of the samples in a mixed manner. The oil lubricant considerably improved the wear behaviour in terms of decreased wear rate, friction coefficient and frictional heating. The lubricant also narrowed down the difference in the wear performance of the zinc-based matrix alloy, composite and cast iron. In other words, the oil lubricant suppressed the effect of microstructural features of the samples on wear behaviour. Typical wear response under specific wear conditions has been discussed in terms of load bearing, lubricating and cracking characteristics of various microconstituents of samples and the effectiveness of oil lubricant to suppress the role played by the phases. The features of wear surfaces, subsurface regions and debris particles could further substantiate the observed wear response of the samples.

Influence of heat treatment parameters on the lubricated sliding wear behaviour of a zinc-based alloy

This investigation deals with the observations made pertaining to the influence of the duration of heat treatment (ageing) on the sliding wear response of a zinc-based alloy. The heat treatment comprised of solutionizing followed by artificial ageing for different durations. Partially lubricated sliding wear tests were carried out at a fixed applied pressure, speed and distance. The heat-treated samples attained less strength and hardness but more elongation over the as-cast one. The wear rate and frictional heating initially decreased with increasing ageing duration. This was followed by the attainment of the minimum and then a reversal in the trend at longer durations of ageing. The tensile strength and hardness decreased with increasing duration of ageing and became stable beyond certain ageing period while elongation followed a reverse trend. The response of the samples has been substantiated through the fractographic features and characteristics of wear surfaces, subsurface regions and debris.

Effect of Sand Concentration in the Medium and Travel Distance and Speed on the Slurry Wear Response of a Zinc-Based Alloy Alumina Particle Composite

Slurry wear characteristics of a zinc-based alloy composite containing 10 wt.% alumina particles have been analyzed by sample rotation technique in this study. The slurry comprised 0.4 g sodium chloride and 0.5 cm3 concentrated sulphuric acid dissolved in one litre of water plus varying concentration (up to 60 wt.%) of sand particles. The traversal distance was varied in the range of 15–500 km while test speeds were maintained at 4.71 and 7.02 m/s. It was observed that the wear response of the composite was influenced by parameters such as traversal speed and distance and the content of the sand particles in the environment. Wear rate reduced with increasing speed when tests were conducted in the liquid-only medium while the trend tended to reverse in the presence of the suspended sand particles in the medium. Further, the wear rate increased initially with distance, attained a peak and decreased thereafter at longer traversal distances. Testing the samples in the environment without sand led to higher wear rate when compared with the ones in the media containing sand. Further, within the liquid plus sand media, intermediate sand content (in the test environment) caused maximum wear rate. In this case, the maximum sand content exhibited minimum wear rate. The wear behaviour of the composite under varying conditions has further been substantiated through the characteristic features of the affected surfaces and subsurface regions. Operating wear mechanisms have been observed to be corrosion assisted erosion and abrasion. The predominance of one mechanism over the other(s) actually controlled the wear response of the composite in specific conditions of wear.

High-stress abrasive wear behaviour of a zinc-based alloy and its composite compared with a cast iron under varying track radius and load conditions

Abstract An attempt has been made in this investigation to study the high-stress abrasive wear behaviour of a zinc-based alloy composite containing SiC particle reinforcement. The influence of the reinforcement phase on wear behaviour was investigated by characterizing the zinc-based matrix alloy under identical test conditions. A cast iron was also investigated on similar lines for comparison purposes. The effects of track radius, test duration and applied load on the wear response of the samples were studied. The wear properties studied were wear rate, friction coefficient and frictional heating. The zinc-based matrix alloy comprised of primary α dendrites, eutectoid α + η and e phase. The composite revealed presence of SiC particles in addition to the features of the matrix alloy. The cast iron showed graphite in a matrix of pearlite and ferrite. The zinc-based matrix alloy attained maximum wear rate and frictional heating, while those for the composite were the least; the response of the cast iron was intermediate between the two in general. The trend observed by friction coefficient was somewhat different in the sense that it was the least for the cast iron while the maximum was still noted for the zinc-based matrix alloy, the composite revealing intermediate response. The wear rate and frictional heating increased with test duration while the friction coefficient was affected in an opposite manner. Increasing load and track radius caused the wear rate, frictional heating and friction coefficient to increase. The wear behaviour of the samples has been substantiated through the characteristics of wear surfaces, debris particles and the abrasive medium.

Effects of silicon content on the mechanical and tribological properties of monotectoid-based zinc–aluminium–silicon alloys

In this work, one binary zinc–aluminium and eight ternary zinc–aluminium–silicon alloys were produced by permanent mould casting. Friction and wear properties of the alloys were investigated in both as-cast and heat-treated conditions using a block-on-ring machine and the results were related to their microstructure and mechanical properties. It was observed that the microstructure of the zinc–aluminium–silicon alloys consisted of aluminium-rich α, zinc-rich η phases and silicon particles. The size and distribution of silicon particles were found to be dependent on the silicon content of the alloys. The heat treatment involving quench-ageing removed the dendritic microstructure of the alloys and produced a fine-grained microstructure, but had no significant effect on the silicon particles. Silicon additions were found to be very effective on mechanical and wear properties of zinc-based alloys. The hardness and the tensile strength of the alloys increased with increasing silicon content up to 2 wt.% Si, above which it decreased as the silicon content increased further. It was also found that friction coefficient and wear rate of the alloys decreased with increasing silicon content up to 2 wt.% Si, but above this level they increased as the silicon content increased further. Among the alloys tested, the highest tensile strength and wear resistance was obtained with the Zn–40Al–2Si alloy. It was also observed that the wear behaviour of the Zn–Al–Si alloys correlates strongly with their hardness, tensile strength and friction coefficient.

Wear response of a zinc-based alloy containing silicon as influenced by material microstructure and test conditions

This paper describes observations pertaining to the sliding wear response of a zinc-based alloy comprising silicon. Wear tests were performed in oil lubricated condition over a range of applied pressures and sliding speeds. The influence of microstructural changes (brought about through heat treatment) on mechanical properties and wear characteristics of the samples has also been investigated. The study indicates that microstructural alterations brought about through heat treatment could be beneficial in terms of improved wear response of the zinc-based alloy despite a reduction in hardness and tensile strength. However, the extent of improvement depends on test conditions like sliding speed and pressure. Factors like hardness, strength, cracking tendency, thermal stability, morphology and mode of distribution of various microconstituents in the alloy microstructure were noted to be responsible for specific wear behaviour in different test conditions. Different slopes exhibited by the data plots could be explained in terms of changing mode of predominance of operating wear mechanisms. The observed wear behaviour of the alloy was substantiated further through the features of wear surfaces, subsurface regions and debris particles.

Slurry Wear Characteristics of a Zinc-Based Alloy

An attempt has been made in this investigation to assess the wear behavior of a zinc-based alloy in slurry. The influence of the sand content of the slurry and traversal speed and distance on the wear response of the alloy has been examined. Tests were also conducted in the liquid-only medium to assess the role played by the suspended sand particles in the medium. Testing the samples in the liquid-only medium (i.e., without sand particles) caused maximum wear rate. It was also observed that an intermediate sand concentration in the liquid exists wherein the samples experienced maximum wear rate (although less than in the liquid-only medium). Further, increasing the speed of rotation of the specimens in the liquid plus sand environments led to higher wear rate while the trend tended to reverse in the sand-free liquid environment. The alloy initially displayed increased wear rate with increasing traversal distance. This was followed by the attainment of the maximum, a decrease in the wear rate and then a steady state value at longer traversal distances. Wear behavior of the alloy under different experimental conditions was further substantiated through the features of the affected wear surfaces and subsurface regions (perpendicular below the affected surfaces).