Effect of the SiC particle size on the dry sliding wear behavior of SiC and SiC–Gr-reinforced Al6061 composites

The effect of size of silicon carbide particles on the dry sliding wear properties of composites with three different sized SiC particles (19, 93, and 146 μm) has been studied. Wear behavior of Al6061/10 vol% SiC and Al6061/10 vol% SiC/5 vol% graphite composites processed by in situ powder metallurgy technique has been investigated using a pin-on-disk wear tester. The debris and wear surfaces of samples were identified using SEM. It was found that the porosity content and hardness of Al/10SiC composites decreased by 5 vol% graphite addition. The increased SiC particle size reduced the porosity, hardness, volume loss, and coefficient of friction of both types of composites. Moreover, the hybrid composites exhibited lower coefficient of friction and wear rates. The wear mechanism changed from mostly adhesive and micro-cutting in the Al/10SiC composite containing fine SiC particles to the prominently abrasive and delamination wear by increasing of SiC particle size. While the main wear mechanism for the unreinforced alloy was adhesive wear, all the hybrid composites were worn mainly by abrasion and delamination mechanisms.     

Investigation of the abrasive wear behaviour of ZA-27 alloy and CuSn10 bronze

In this study, abrasive wear behaviours of ZA-27 alloy and CuSn10 bronze were investigated using a purpose-built wear tester. The ZA-27 alloy was produced by permanent mould casting. The abrasive SiC particles having 63 μm grit size was added to the lubricant oil. The wear rate and friction coefficient of alloys were determined at the different test conditions such as sliding distance, applied load, linear velocity and percentage SiC weight content. The wear surfaces of alloys were examined using SEM and EDS analysis. The results showed that the wear rate of alloys decreased with the increasing of applied load and increased with the increasing linear velocity and abrasive SiC content. It was found that the SiC particle fracture was an important mechanism determining the friction and the wear rate of alloys. CuSn10 bronze showed higher wear resistance than ZA-27 alloy under abrasive test conditions except at high linear velocities.     

Effect of aging on the abrasive wear properties of AlMgSi1 alloy

In this paper, the wear performance of the aged AlMgSi1 alloy was investigated. Great improvements in mechanical properties of Al alloys can be achieved by suitable solution treatment and aging operations. A pin-on-disk wear machine was designed and developed for abrasive wear tests. The wear resistance was evaluated using a pin-on-disk wear testing method with a SiC abrasive paper counterface. The variation of wear volume is presented as a function of applied normal load, abrasive grit size and sliding distance for running speed. Mass losses were measured within a load range of 6.45–11 N, a sliding velocity range of 0.078–0.338 m/s and abrasive grit size of 5–30 μm. The effects of different sliding speeds and loads on wear resistance and surface roughness were also examined. It was measured amounts of mass loss and examined worn surfaces. Metal microscope was used to study the microstructures of the wear scars. Natural aged specimen observed maximum wear resistance.     

Tribological properties of powder metallurgy – Processed aluminium self lubricating hybrid composites with SiC additions

In this experimental study, aluminium (Al)-based graphite (Gr) and silicon carbide (SiC) particle-reinforced, self-lubricating hybrid composite materials were manufactured by powder metallurgy. The tribological and mechanical properties of these composite materials were investigated under dry sliding conditions. The results of the tests revealed that the SiC-reinforced hybrid composites exhibited a lower wear loss compared to the unreinforced alloy and Al–Gr composites. It was found that with an increase in the SiC content, the wear resistance increased monotonically with hardness. The hybridisation of the two reinforcements also improved the wear resistance of the composites, especially under high sliding speeds. Additionally, the wear loss of the hybrid composites decreased with increasing applied load and sliding distance, and a low friction coefficient and low wear loss were achieved at high sliding speeds. The composite with 5 wt.% Gr and 20 wt.% SiC showed the greatest improvement in tribological performance. The wear mechanism was studied through worn surface and wear debris analysis as well as microscopic examination of the wear tracks. This study revealed that the addition of both a hard reinforcement (e.g., SiC) and soft reinforcement (e.g., graphite) significantly improves the wear resistance of aluminium composites. On the whole, these results indicate that the hybrid aluminium composites can be considered as an outstanding material where high strength and wear-resistant components are of major importance, predominantly in the aerospace and automotive engineering sectors.     

Wear behaviour of an Al–12% Si alloy reinforced with a low volume fraction of SiC particles

Aluminium–silicon alloys reinforced with low volume fractions of SiC particles were prepared by the compocasting process. The wear behaviour of the unreinforced Al–12Si alloy and metal-matrix composites (MMCs) was investigated by using a block-on-ring test at room temperature under dry conditions. The results showed that the addition of a low volume fraction of SiC particles (2–8 vol%) is a very effective way of increasing the wear resistance of the matrix alloy. Metallographic examinations revealed that the wear zone of the Al–12Si alloy consists of both hardened and deformation layers. The depth of the hardened layer depended on the applied load and was in the vicinity of 10–50 μm. The formation of the hardened layer was related to the alignment and redistribution of fragmented eutectic phase to the surface region during sliding wear. Furthermore, the delamination of debris from the hardened layer was responsible for a higher wear loss observed in the Al–12Si alloy. The thickness of the hardened layer formed on the MMC specimens was reduced considerably by the incorporation of fragmented SiC particles. This layer exhibited higher hardness and wear resistance than that developed in the unreinforced alloy.     

Effect of sliding distance on the wear and friction behavior of as cast and heat-treated Al–SiCp composites

The present investigation aims to evaluate the effect of sliding distance on the wear and friction behavior of as cast and heat-treated Al–SiCp composites using pin-on-disc wear testing machine, giving emphasis on the parameters such as wear rate and coefficient of friction as a function of sliding distance (0–5000 m) at different applied pressures of 0.2, 0.6, 1.0 and 1.4 MPa, and at a fixed sliding speed of 3.35 m/s. Characterizing the alloy and composites in terms of microstructure, X-ray diffraction analysis, microhardness and wear surface analysis. The results revealed that the heat-treated composite exhibited superior wear properties than the base alloy, while the coefficient of friction followed an opposite trend. Moreover, the wear rate of the composite is noted to be invariant to the sliding distance and increased with applied pressures. Microstructure of composite shows fairly uniform distribution of SiC particles in the metallic matrix. The hardness value of heat-treated composite increased 20–30% by addition of SiC particles to the alloy, intermetallic phases like Al₂Mg₃ and Al₂CuMg, etc., were obtained from X-ray analysis. The wear mechanism of the investigated materials was studied through worn surfaces examination of the developed wear tracks.     

Cu对粉末冶金Fe3Al基复合材料性能的影响

研究了Cu含量对粉末冶金Fe3Al基复合材料的烧结性能和力学性能的影响,分析了施加载荷和改变转速对加入不同量铜粉末冶金Fe3Al基复合材料的摩擦磨损性能的影响,并借助电子显微镜和能谱分析了不同铜含量Fe3Al基复合材料的磨损机理.结果表明:加入12%的Gu可使Fe3Al基复合材料具有良好的烧结性能和力学性能;载荷和转速对复合材料的磨损形式受铜的加入量的影响;铜的加入影响复合材料的磨损形式和磨损机理,当含铜量较少时,复合材料以磨粒磨损为主,随加入铜的量的增多,其磨损形式变为磨粒磨损和轻微的粘着磨损形式,加入大量铜时,则以粘着磨损为主.     

Sliding wear behaviour of Al-Si-Cu composites reinforced with SiC particles

Abstract

The sliding wear behaviours of an unreinforced monolithic Al-Si-Cu alloy and SiC particles reinforced composites containing 5, 13, 38 and 50 vol.-% with diameters of 5.5, 11.5 and 57μm were investigated. The results showed that the wear resistance of the composites is much higher than the monolithic alloy, and the larger and the more SiC particles, the higher the enhancement of the wear resistance. Metallographic examinations revealed that the subsurface of worn composites was composed of both fragmented particles and deformed matrix alloy. The depth of the particle fracture zone in the subsurface varied in the range of 20-35 μm at a sliding distance of 1.8 km, while the plastic deformation zone of the worn subsurface on monolithic alloy was more than 100 μm. Scanning electron microanalyses of the worn surface, subsurface microstructure and debris suggested that the depth of the particle fracture zone became smaller as the diameter of SiC particles increased. Increasing the hardness and decreasing the applied wear stress changed the debris morphology from flake to very small lumps.     

Process and wear behavior of monolithic SiC and short carbon fiber-SiC matrix composite

The process and wear behavior of monolithic SiC and 10 vol. % short carbon fiber-SiC matrix (C-SiC) composite have been studied. The results indicate that, among ethyl alcohol, acetone, n-hexane and n-octyl alcohol, n-octyl alcohol was the most effective dispersing agent in dispersing both SiC powder and short carbon fiber. Among AlN, Al₂O₃, B₄C, graphite, AlN/B₄C, AlN/graphite, B₄C/graphite and Al₂O₃/B₄C, the most effective sintering aid for the fabrication of SiC and C-SiC composite was a mixture of 2 wt% AlN and 0.5 wt% graphite. The monolithic SiC hot-pressed at 2100°C exhibited higher density but lower flexural strength than those hot-pressed at 2000°C due to a grain growth effect. For the C-SiC composite, both density and strength of the composite hot-pressed at 2100°C were generally higher than those hot-pressed at 2000°C. The density and strength of C-SiC composite were lower than those of monolithic SiC under the same hot pressing conditions due to a higher porosity level in the composite. When monolithic SiC slid against C-SiC composite, the weight losses of SiC and the composite were each less than that of self-mated SiC or self-mated C-SiC. In the self-mated SiC tribosystem, a mechanically stable film could not be established, resulting in an essentially constant wear rate. When sliding against C-SiC, a thin, smooth and adherent debris film was quickly formed on the SiC surface, resulting in a lower wear.     

Improving sliding and abrasive wear behaviour of cast A356 and wrought AA7075 aluminium alloys by plasma electrolytic oxidation

An important limitation of aluminium alloys for mechanical applications is their poor tribological behaviour. In this study, surface treatment by plasma electrolytic oxidation (PEO) has been applied to two widely used aluminium alloys: A359 (hypoeutectic Al–Si–Mg) cast alloy and AA7075 (Al–Zn–Mg–Cu) wrought alloy, in order to improve their wear resistance, under sliding and abrasive wear conditions. The main aim of this work was the comparison of the properties and wear resistance of the oxide layers grown under the same PEO treatment conditions on two different aluminium alloys which might be coupled in engineered components. Significant differences in the phase composition, microstructure and mechanical properties measured by microindentation were observed in the oxide layers grown on the two substrates, and were ascribed to the effects of the different compositions and microstructures of the substrate alloys. Abrasion tests were carried out in a micro-scale abrasion (ball-cratering) test, with both alumina and silicon carbide abrasive particles. The results demonstrated the influence of the abrasive material on wear behaviour: whereas relatively aggressive SiC particles gave comparable results for both PEO treated and untreated samples, with the less aggressive Al₂O₃ abrasive the wear rates of the PEO treated samples, for both substrates, were significantly lower than those of the untreated substrates. In unlubricated sliding the PEO treatment significantly increase the wear resistance of both the aluminium alloys, at low applied load. In this condition the wear behaviour of the PEO treated alloys is strongly influenced by the stability of a protective Fe–O transfer layer, generated by wear damage of the steel counterpart. Under high applied loads however, the transfer layer is not stable and the hardness of the PEO layer, as well as the load bearing capacity of the substrate, become the main factors in influencing wear resistance.     

Sliding friction and wear behaviour of vinylester and its composites under dry and water lubricated sliding conditions

In this paper, we studied and explored the tribological performance of pure vinylester (V), glass fiber reinforced (GFR), SiC filled glass fiber reinforced vinylester composite under dry and water lubricated sliding conditions. Friction and wear tests were carried out with configuration of a pin on a rotating disc under ambient conditions. Tests were conducted at normal load 10, 30 and 50 N and under sliding speed of 1.6 m/s, 2.8 m/s and 4 m/s. The results showed that the coefficient of friction decreases with the increase in applied normal load values both under dry and water lubricated conditions. On the other hand for pure vinylester specific wear rate increases with increase in applied normal load under dry sliding condition and decreases with increase in applied normal load under water lubricated conditions. However the specific wear rate for GFR vinylester composite and SiC filled GFR vinylester composite decreases with the increase in applied normal load both under dry and water lubricated conditions. Moreover, for the range of load and speeds used in this investigation the coefficient of friction and specific wear rates using water lubricant registered lower values than that of the dry condition. The specific wear rates for pure vinylester and vinylester + 50 wt.% GFR and SiC filled GFR vinylester composite under dry and water lubricated sliding condition were in the order of 10⁻⁷ mm³ N⁻¹ mm⁻¹.     

Microstructural control by spray forming and wear characteristics of a Babbit alloy

The effect of process variables during spray forming of a commercial Babbit alloy containing Pb74–Sn12–Sb11.5–Cu1.25–NiO.75–Cd0.3–As0.2 on its microstructure and wear characteristics were investigated. Variation in atomization gas pressure from 0.6 to 1.2 MPa and nozzle to substrate distance from 0.2 to 0.4 m revealed considerable change in the nature of porosity and microstructural features of the spray deposits. The process variables during spray deposition were optimized to achieve microstructural homogeneity and refinement in second phase particles of this alloy. The wear study of both the spray formed and as-cast alloy under an applied load of 10 to 70 N and sliding velocity of 0.2 to 1.5 ms-1 indicated two distinct regimes of mild and severe wear. In both the regimes, the spray-formed alloy consistently indicated a low wear rate compared to that of the as-cast alloy. In addition, the mild wear regime of the spray-formed alloy was extended to higher load and sliding velocity. Wear characteristics of the spray formed alloy is discussed in light of its microstructural features induced during spray deposition processing.     

Effect of sillimanite particle reinforcement on dry sliding wear behaviour of aluminium alloy composite

Abstract

The effect of sillimanite reinforcement on the dry sliding wear behaviour of aluminium silicon alloy (BS LM6) composite was investigated using a pin-on-disc sliding wear test machine. The composite specimens were prepared using the liquid metallurgy technique and 10 wt-% of sillimanite particles were incorporated in the matrix alloy. Sliding wear tests were conducted at applied pressures between 0.2 and 1.6 MPa and speeds of 1.89, 3.96 and 5.55 m s^-1. The matrix alloy was also prepared and tested under identical conditions in order to enable comparison. It was observed that the sillimanite reinforced composite exhibited a lower wear rate than the matrix alloy. Increase in applied load increased the wear rate while increase in speed exhibited the reverse effect. The seizure pressure of the composite was significantly higher than that of the matrix alloy. The temperature rise near the contacting surface and the coefficient of friction were less in the composite than in the matrix alloy. SEM micrographs of the worn surface and subsurface were used to predict the nature of the wear mechanism.     

SiC particulate dispersed composites of an Al–Zn–Mg–Cu alloy: Property comparison with parent alloy

Composites have been formed by adding 15 wt.% of SiC dispersoids in the size range of 20–40 μm to Al–Zn–Mg–Cu alloy (corresponding to the 7075 series). The 7075 aluminium alloy and composites have been subjected to heat treatment in an attempt to optimize their properties. The present paper reports the improvement in the hardness, mechanical and sliding wear resistance properties attained as a result of heat treatment and forming composites. An attempt is made in the paper to understand the mechanism responsible for the improved behaviour of the 7075/SiC aluminium composite over the base alloy through microscopic/metallographic analysis.     

Abrasive wear behaviour of zinc-aluminium alloy - 10% Al2O3 composite through factorial design of experiment

Two body abrasive wear behaviour of a zinc-aluminium alloy - 10% Al₂O₃ composite was studied at different loads (1–7 N) and abrasive sizes (20–275 m) as a function of sliding distance and compared with the matrix alloy. The wear rate of the composite and the matrix alloy has been expressed in terms of the applied load, abrasive size and sliding distance using linear factorial design approach. The study suggests that the wear rate of the alloy and composite follow the following relations:

Electrodeposited composite coating of Ni-W-P with nano-sized rod- and spherical-shaped SiC particles

In this research, Ni-W-P-SiC nanocomposite coatings are electrodeposited from the plating solution containing suspension of nano-sized spherical- and rod-shaped SiC particles. The influence of SiC particle charge, applied current density, surfactant addition and the particle shape on the SiC incorporation rate has been studied. The phase structure, microhardness and wear resistance of Ni-W-P-SiC nanocomposite coatings were evaluated using X-ray diffraction (XRD), microhardness tester and wear test apparatus. The surface morphology of the produced coatings and worn surfaces has been investigated using scanning electron microscope (SEM). Additionally, the composite coating exhibited higher hardness and wear resistance than the pure Ni-W-P alloy. Regardless the particle shape, the mechanical characteristics of composite coatings are improved with increasing of SiC wt.% into the matrix. The corrosion behavior of the produced coatings was studied using anodic polarization measurements. The nanocomposite coating incorporating SiC rods exhibited higher mechanical and corrosion performance compared with deposits with spherical SiC nano-particles.     

Dry sliding wear behavior of cast SiC-reinforced Al MMCs

Dry sliding block-on-ring wear tests were performed on a squeeze cast A390 Al alloy, a high pressure die cast 20%SiC–Al MMC, and a newly developed as-cast 50%SiC–Al MMC. The testing conditions spanned the transition that control the mild to severe wear for all materials. The results show that the sliding wear resistance increases as SiC particle volume fraction increases. The critical transition temperature, at which wear rates transit from mild to severe, also increases with increasing SiC content. Examination of the wear surfaces, the subsurface characteristics, and the wear debris indicate that a hard ‘mechanically alloyed’ layer, high in SiC content, forms on the sliding surface of the 50%SiC composite. This layer prevents the surface adhesion wear mechanisms active in the A390 alloy, and it inhibits delamination wear mechanisms that control the mild wear of the 20%SiC composite. As a result, mild wear of the 50%SiC composite occurs by an oxidation process. In the 20%SiC material, severe wear occurs as a consequence of material removal by a flow-related extrusion-like process. In contrast, the high SiC content prevents plasticity in the 50%SiC composite, which eventually is susceptible to severe wear at very high temperatures (≈450 °C) due to a near-brittle cracking processes.     

Mechanical and tribological properties of LM13/TiO2/MoS2 hybrid metal matrix composite synthesized by stir casting

This paper involves the fabrication of LM13/TiO₂ (12?wt%)/MoS₂ (3?wt%) hybrid metal matrix composite and unreinforced alloy using liquid metallurgy route and evaluation of mechanical properties and adhesive wear characteristics. Microstructural investigation revealed homogeneous distribution of reinforcements in matrix. Hardness and tensile properties revealed that the composite had attained an improvement of 16.5 and 35%, respectively, over alloy. Wear characteristics were analyzed using pin-on-disk tribometer by varying load (10–40?N), sliding velocity (1–4?m/s), and sliding distance (500–2000?m). Statistical analysis was performed using response surface methodology to obtain the optimum wear process parameters for achieving maximum wear resistance. Results revealed that, with increasing load and sliding velocity, an increment in wear rate was observed for both alloy and composite, while a decline was observed with increasing sliding distance for composite and vice versa for alloy. Worn surface analysis revealed that load plays a prominent role in deciding wear rate, followed by sliding velocity. Sliding distance had less effect on wear rate of composite while it had significance on alloy. This hybrid composite can replace the conventional material used in automotive applications involving tribological importance.     

Wear characteristics of spray formed Al-alloys and their composites

In the present investigation, different Al based alloys such as Al–Si–Pb, Al–Si, Al–Si–Fe and 2014Al + SiC composites have been produced by spray forming process. The microstructural features of monolithic alloys and composite materials have been examined and their wear characteristics have been evaluated at different loads and sliding velocities. The microstructural features invariably showed a significant refinement of the primary phases and also modification of secondary phases in Al-alloys. The Pb particles in Al–Si–Pb alloy were observed to be uniformly distributed in the matrix phase besides decorating the grain boundaries. The spray formed composites showed uniform distribution of SiC particles in the matrix. It was observed that wear resistance of Al–Si alloy increases with increase in Pb content; however, there is not much improvement after addition of Pb more than 20%. The coefficient of friction reduced to 0.2 for the alloy containing 20%Pb. A sliding velocity of 1 ms⁻¹ was observed to be optimum for high wear resistance of these materials. Alloying elements such as Fe and Cu in Al–Si alloy lead to improved wear resistance compared to that of the base alloy. The addition of SiC in 2014Al alloy gave rise to considerable improvement in wear resistance but primarily in the low pressure regime. The wear rate seemed to decrease with increase in sliding velocity. The wear response of the materials has been discussed in light of their microstructural features and topographical observation of worn surfaces.     

Production and properties of SiCp-reinforced aluminium alloy composites

A vacuum infiltration process was developed to produce aluminium alloy composites containing various volume fractions of ceramic particles. The matrix composites of aluminium with 9.42 wt%Si and 0.36 wt%Mg containing up to 55 vol% SiCp were successfully infiltrated and the effect of infiltration temperature and volume fraction of particle on infiltration behaviour was investigated. In addition to aluminium powder, magnesium was used to improve the wetting of SiC particles by the molten aluminium alloy. The infiltration rate increased with increasing infiltration time, temperature and volume fraction of particle, but full infiltration appeared at the optimum process parameters for the various volumes of fraction composite compacts. In addition, the microstructure, hardness, density, porosity and wear resistance of the composites were also examined. It is observed that the distribution of SiC particles was uniform. The hardness and density of the composite increased with increasing reinforcement volume fraction and porosity decreased with increasing particle content. Moreover, the wear rate of the composite increased with increasing load and decreased with increasing particle content.