Fabrication of light-weight Al LM13/TiS2 metal matrix composites and investigation of its wear characteristics

This paper aims to study the dry sliding wear characteristics of LM13 aluminum alloy matrix containing titanium disulfide (TiS₂) as the reinforcement (10?wt%, average size 37?µm) fabricated through liquid metallurgy route. Microstructural examination and Vickers hardness test were performed on the sample to investigate uniform distribution of the reinforcement particles in the composite. Energy Dispersive X-Ray Analysis and X-Ray Diffraction techniques were used to characterize the composite. The hardness test gave a result of 105.94 HV. The dry sliding wear experiments were designed by a five-level central composite design developed using response surface methodology. The factors considered were load, sliding distance, and velocity which were varied in the range of 10–30?N, 500–1500?m, and 1–3?m/s, respectively. The experiments were then performed at room temperature using a pin-on-disc tribometer for 20 combinations. The generated regression equation showed that the developed model established a proper relation between the process variables and the response. Load being the most influential factor showed increasing trends of wear rate in the surface plots against both velocity and sliding distance. The wear rate exhibited a nonlinear trend in the surface plots against sliding distance and velocity. Scanning electron microscopy results showed greater wear at higher loads due to higher surface damage. Thus, the fabricated Al/TiS₂ composite with the optimum wear process parameters can be well utilized for application where wear becomes a major consideration.     

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.     

Sliding wear of Al2O3P/6061 Al composite

The mild sliding wear behaviour of a 15 vol % Al₂O_3P/6061 Al composite has been investigated by using a pin-on-disc reciprocating sliding machine. The composite has been shown to exhibit an excellent wear resistance as compared to the unreinforced matrix alloy. The wear rate of the composite under dry wear conditions with a 12N load is approximately one tenth of that in the 6061 aluminium alloy. The wear rate of the composite under lubrication with 15W/40 gear oil under a 100N load is only one thousandth ofthat in the 6061 aluminium alloy.The dry wear resistance of an over-aged sample is shown here to be better than a peak aged or under-aged sample when the composite was aged at 160°C. The coefficient of friction of the composite was approximately 0.5–0.6 under dry conditions and 0.07 in lubricated wear experiments.In the initial stage, the worn surface of the composite under dry conditions is primarily composed of ploughed grooves and ductile tear. The composite makes a conducting contact with the steel pin. The worn surface is composed of compacted powder and the contact potential gradually increases when the period of the wear experiment goes beyond 2 h.     

The effect of strontium on the microstructure and wear properties of A356–10%B4C cast composites

This study was undertaken to investigate the effect of strontium (0.5%) as a modifier on the microstructure and dry sliding wear behavior of A356–10%B₄C particulate metal matrix composite (PMMC). The composite ingots were made by stir casting process. In this work, composite were characterized by scanning electron microscope equipped with energy dispersive spectrometer (EDS), and dry sliding wear experiment were performed in a pin-on-disc wear tester against a DIN 100Cr6 steel disc at speed of 0.5 ms⁻¹ and normal loads of 20, 40 and 60 N. The obtained results showed that 0.5%Sr was needed to modify of silicon eutectic in A356–10%B₄C cast composite. Also, the wear results showed that the addition of strontium to MMCs can lead to reduction of wear rate through strong bonding (between B₄C and matrix) and silicon particle modification. Formation of compact transfer layer has been identified on the entire surface of the pins at the applied load of 60 N. It is suggested that the transfer layer which was formed under an applied load of 60 N can act as a protective layer and helps to reduce wear rate.     

Comparative study of wear performance of particulate and fiber-reinforced nano-ZnO/ultra-high molecular weight polyethylene hybrid composites using response surface methodology

The effects of two types of filler reinforcements i.e. particulate (talc particles) and fiber (Glass Fiber (GF)) as secondary reinforcements in ultra-high molecular weight polyethylene (UHMWPE)-based composites on the wear and friction properties were discussed in this paper. These UHMWPE hybrid composites were fabricated by the addition of 10 wt% of talc and glass fiber at a fixed nano-ZnO loading of 10 wt% using a hot compression moulding technique. The wear and friction properties of these hybrid composites were investigated using a pin-on-disc tester with different operating conditions of applied loads, sliding speeds and sliding distances based on response surface Box–Behnken design. Response Surface Methodology (RSM) was applied to model the effects of various variables of applied load, sliding speed and distance on the wear volume loss and average coefficient of friction (COF) of UHMWPE hybrid composites. The mathematical regression models of the wear volume and average COF were derived from the analysis of variance (ANOVA). Optimization of the independent variables to minimize the wear and friction responses of both UHMWPE composites was estimated using RSM. The mathematical models showed that applied load, sliding speed and distance have significant effects on the wear and friction properties of both UHMWPE composites in the tested range of variables. The most significant, in order of the variables that affect the volume loss and friction of UHMWPE composites is load, followed by sliding distance and speed. In addition, the combined effects of load and distance indicate the highest significance on volume loss and average COF for both UHMWPE hybrid composites as compared to other variable interactions. GF/ZnO/UHMWPE exhibited better wear performance compared to talc/ZnO/UHMWPE hybrid composites. The severity of worn surfaces of the GF/ZnO/UHMWPE was less than that of talc/ZnO/UHMWPE. The GF/ZnO/UHMWPE produced transfer films that were more uniform and had better coverage compared to talc/ZnO/UHMWPE.     

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.     

The mechanical properties and abrasive wear behavior of functionally graded aluminum/AlB2 composites produced by centrifugal casting

Functionally graded aluminum composites reinforced with different average sized (15, 44, and 74 µm) aluminum diboride (AlB₂) particles (10 wt%) have been fabricated through centrifugal casting process. The outer, middle, and inner surfaces of all the functionally graded composites were tested for their microhardness using a Vicker's hardness tester. The outer and inner zones of all the composites were investigated for their tensile strength using a universal testing machine. The abrasive wear test was conducted using dry abrasion tester on the outer region of the composites based on Taguchi's design of experiments, under the influence of parameters such as load, speed, and reinforcement size. The analysis of variance was performed and determined that load has major significance on the wear rate followed by reinforcement size and speed. Scanning electron microscopy analysis was performed on the worn-out surfaces and it was observed that outer surface of coarser particle reinforced composite with lesser scratches and minimum loss of material.     

Study on three-body abrasive wear behavior of functionally graded Al/TiB2 composite using response surface methodology

Functionally graded LM13 Al/10?wt% TiB₂ metal matrix composite has successfully produced under centrifugal casting. Hollow cylindrical composite with dimensions 150?×?150?×?15?mm was produced under rotating centrifugal speed of 1100?rpm. Microstructural characteristics were studied on the composite surfaces at distance of 1, 5.5, and 10?mm from outer periphery of the casting, and the results revealed that surface at distance of 1?mm has presence of more reinforcement particles. An objective of this study was to characterize abrasion wear behavior at the composite surfaces using dry abrasion tester. Mathematical models were developed using response surface methodology to study the relationship of parameters such as load, speed, and distance from outer periphery with abrasion wear rate. Face centered Central Composite Design with 20 experiments was preferred for dry abrasion test. Adequacy of model was predicted through analysis of variance, and the significance test result shows that load has major impact on the wear rate. The optimized parametric condition to obtain minimum wear rate was found as load of 33?N, speed of 112?rpm, and distance of 1?mm from outer periphery. Scanning electron microscopy analysis done at worn out surface showed maximum wear resistance at the outer periphery.     

Dry sliding wear behavior of heat treated hybrid metal matrix composite using Taguchi techniques

Dry sliding wear behavior of zinc based alloy and composite reinforced with SiCp (9 wt%) and Gr (3 wt%) fabricated by stir casting method was investigated. Heat treatment (HT) and aging of the specimen were carried out, followed by water quenching. Wear behavior was evaluated using pin on disc apparatus. Taguchi technique was used to estimate the parameters affecting the wear significantly. The effect of HT was that it reduced the microcracks, residual stresses and improved the distribution of microconstituents. The influence of various parameters like applied load, sliding speed and sliding distance on wear behavior was investigated by means and analysis of variance (ANOVA). Further, correlation between the parameters was determined by multiple linear regression equation for each response. It was observed that the applied load significantly influenced the wear volume loss (WVL), followed by sliding speed implying that increase in either applied load or sliding speed increases the WVL. Whereas for composites, sliding distance showed a negative influence on wear indicating that increase in sliding distance reduces WVL due to the presence of reinforcements. The wear mechanism of the worn out specimen was analyzed using scanning electron microscopy. The analysis shows that the formation and retention of ceramic mixed mechanical layer (CMML) plays a major role in the dry sliding wear resistance.     

铝/石墨复合材料高速高温下的摩擦磨损特性

本文研究了用中间法新工艺制造的铝石墨复合材料在高速高温下的摩擦磨损特性。试验在销盘式试验机上进行。滑动线速度最高达9.4米/秒。在2米/秒干摩擦时,所有测试的复合材料磨损量均小于基体合金。200℃时,含石墨2～5%的复合材料磨损量也此基体合金小。在9.4米/秒干摩擦时,含石墨2%的复合材料耐磨性能最好。以前曾有报导:滑动线速度大于1米/秒,铝石墨复合材料的磨损量大于基体合金[12,13]。本文认为新工艺制造的复合材料在9.4米/秒的高速摩擦时摩擦系数和磨损量下降是由于石墨与基体界面结合良好。      

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.     

Study on the effects of nanoparticulates of SiC,Al2O3, and ZnO on the mechanical and tribological performance of epoxy-based nanocomposites

In this research work, mechanical and tribological characteristics of ortho cresol novalac epoxy (OCNE)-based nanocomposites filled with nanoparticulates of SiC, Al₂O_3, and ZnO have been investigated. Also, in these investigations, the influence of wear parameters such as applied normal load, sliding velocity, filler contents, and sliding distance have been explored. The experimental plan for four factors at three levels using face centered composite design (CCD) has been employed by the response surface methodology (RSM) technique. The friction and wear tests were carried out using a pin on disc wear test apparatus under dry sliding conditions. The hardness and flexural strength of nano ortho cresol novalac epoxy composites filled with nano (SiC, Al₂O_3, and ZnO) particulates increases with an increase in the filler contents. Whereas, the tensile strength of these nanocomposites increases with an increase in the filler contents from 1 to 2 wt%, and with a further increase in filler contents the tensile strength decreases. The results of the study also showed that (2 wt%) filler contents bring superior mechanical and tribological properties. The lowest coefficient of friction and specific wear rate were found with nano Al₂O₃-filled composites. Also, the wear mechanisms of these nanocomposites were studied using a scanning electron microscope (SEM) equipped with an EDS analyzer.     

The preparation and the friction and wear behaviours of TiO2/CNT/PI composite film

Recently, the tribological properties of polyimide composites filled with TiO₂ nanoparticles and short pitch-based carbon nanotubes (CNTs) were investigated. Sliding tests were performed on a co-rotating twin-screw extruder under different temperatures and regular pressure and speed. It was found that the composite with 4 wt% TiO₂ and 6 wt% CNT could reduce the frictional coefficient and wear rate in the most effective way. Compared to the conventional hybrid composites up to now, the above composite was characterised by relatively lower filler content, which would reduce the manufacturing cost. Therefore, it could be largely processed in practice. Increased surface hardness, lubricating effect of the sheet-like wear debris reinforced by TiO₂ and rapidly formed transfer film were believed to be the key issues accounting for the obvious wear-resisting and friction-reducing behaviours.     

(Mg2B2O5w+ND)/ZK60镁基复合材料的摩擦磨损性能研究

在湿球磨条件下以600 r/min高能球磨混粉,并将球磨后的粉末经过热压烧结-热挤压成型制备(Mg2B2O5w+ND)/ZK60镁基复合材料。研究了(Mg2B2O5w+ND)/ZK60镁基复合材料在不同载荷和转速下的干摩擦磨损性能。结果表明:干摩擦条件下,材料的摩擦系数随着滑动距离的增加会经历跑和阶段和稳定阶段;材料的质量磨损率随着转速的增大而降低,随着载荷的增大而增大,且基体镁合金的质量磨损率始终低于复合材料。随着摩擦载荷和转速的增加,材料的摩擦系数减小,然后逐渐趋于平稳。混杂增强的镁基复合材料相比基体合金具有更低的摩擦系数。     

Effect of addition of graphite particulates on the wear behaviour in aluminium–silicon carbide–graphite composites

Aluminium matrix composites with multiple reinforcements (hybrid AMCs) are finding increased applications because of improved mechanical and tribological properties and hence are better substitutes for single reinforced composites. Few investigations have been reported on the tribological behaviour of these composites with % reinforcement above 10%. The present study focuses on the influence of addition of graphite (Gr) particulates as a second reinforcement on the tribological behaviour of aluminium matrix composites reinforced with silicon carbide (SiC) particulates. Dry sliding wear tests have been performed to study the influence of Gr particulates, load, sliding speed and sliding distance on the wear of hybrid composite specimens with combined % reinforcement of 2.5%, 5%, 7.5% and 10% with equal weight % of SiC and Gr particulates. Experiments are also conducted on composites with % reinforcement of SiC similar to hybrid composites for the sake of comparison. Parametric studies based on design of experiments (DOE) techniques indicate that the wear of hybrid composites decreases from 0.0234 g to 0.0221 g as the % reinforcement increases from 3% to 7.5%. But the wear has a tendency to increase beyond % reinforcement of 7.5% as its value is 0.0225 g at.% reinforcement of 10%. This trend is absent in case of composites reinforced with SiC alone. The values of wear of these composites are 0.0323 g, 0.0252 g and 0.0223 g, respectively, at.% reinforcement of 3%, 7.5% and 10% clearly indicating that hybrid composites exhibit better wear characteristics compared to composites reinforced with SiC alone. Load and sliding distance show a positive influence on wear implying increase of wear with increase of either load or sliding distance or both. Whereas speed shows a negative influence on wear indicating decrease of wear with increase of speed. Interactions among load, sliding speed and sliding distance are noticed in hybrid composites and this may be attributed to the addition of Gr particulates. Such interactions are not present in composite reinforced with SiC alone. Mathematical models are formulated to predict the wear of the composites.     

Microstructure and Wear Resistance of Semisolid TiB2/7050 Composites Produced by Serpentine Tube Pouring Technique

TiB₂/7050 (3, 6, and 9 wt%) composites slurries with globular were synthesized by in situ reaction and serpentine tube pouring techniques. The results showed that the semisolid 7050 alloy and 3, 6, and 9 wt%TiB₂/7050 composites with average grain diameter of 28, 25, 20, and 19 µm and shape factor of 0.77, 0.83, 0.90, and 0.93, respectively, can be obtained at 660 °C pouring temperature. With increasing TiB₂ content and curves number, the α-Al grain size was decreased. The composite melts have an effect of “self-stirring” when they flow through the serpentine tube, which is beneficial to make the primary nuclei with globular grains. Moreover, the wear resistance of TiB₂/7050 composites improved obviously with increasing in situ TiB₂ particles content and that the wear rate of 9 wt%TiB₂/7050 composite was 79% lower than that of 7050 matrix alloy under 100 N applied load, 30 min sliding time, and 0.15 m/s sliding velocity.     

Dry sliding wear behaviour of zinc oxide reinforced magnesium matrix nano-composites

The main objective of the present work is to investigate the dry sliding wear behaviour of a magnesium matrix composite reinforced with zinc oxide nano-particles. Magnesium matrix composites have many applications, especially in the automotive and aerospace industries, due to their superior specific properties. A magnesium matrix composite with 0.5 vol.% ZnO nano-reinforcement was prepared using powder metallurgy and was hot extruded to eliminate pores. The wear behaviour of the Mg/ZnO nano-composite was investigated by conducting dry sliding tests as a function of wear with an oil-hardened non-shrinking (OHNS) steel disc as the counterpart on a pin-on-disc apparatus. Wear tests were conducted for normal loads of 5, 7.5 and 10 N at sliding velocities of 0.6, 0.9 and 1.2 m/s at room temperature. The variations of the friction coefficient and wear rate with the sliding distances (500 m, 1000 m and 1600 m) for different normal loads and sliding velocities were plotted and analysed. To study the dominant sliding wear mechanism for various test conditions, the worn surfaces were analysed using scanning electron microscopy. The wear rate was found to increase with the load and sliding velocity.     

流变成形压力对Al2Y/AZ91镁基复合材料摩擦磨损行为的影响

采用销盘式摩擦副,在转速为100 r/min干摩擦条件下,结合OM、SEM结果,考察了不同载荷与成形压力对流变成形Al2Y/AZ91镁基复合材料(质量分数2%Y)摩擦磨损性能的影响,并探究耐磨性与材料显微组织、力学性能之间的关系.研究表明:在相同的实验载荷下,随着制备复合材料流变成形压力的增加,材料的磨损质量和摩擦系数减少,本实验条件下最大成形压力为100 MPa时磨损量和摩擦系数最小,摩擦磨损性能较佳;对于在相同成形压力下制备的镁基复合材料,磨损质量随着载荷的提升而增大,而摩擦系数有所降低.当载荷较小时,Al2Y/AZ91镁基复合材料的磨损机制以磨粒磨损为主;随着载荷的增大,磨损机制逐步发生转变;当载荷较大时,磨损机制以剥层磨损为主.     

Comparative analysis of wear behavior of garnet and fly ash reinforced Al7075 hybrid composite

Al7075 hybrid composites reinforced with varying weight percentage (0 wt.%, 5 wt.%, 10 wt.%, 15 wt.%) of each of garnet and fly ash were fabricated and characterized for their comparative wear assessment. The sliding wear test was conducted on a reciprocating tribometer in dry medium under the working conditions of applied normal load (2 N, 4 N, 6 N, 8 N), sliding velocities (0.04 m/s, 0.08 m/s, 0.12 m/s, 0.16 m/s), sliding distance (20 m, 40 m, 60 m, 80 m) and working temperature (25 °C, 50 °C, 75 °C, 100 °C). The experiments were performed as per steady‐state condition and Taguchi (L₂₅) orthogonal array design to evaluate specific wear rate of the Al7075 hybrid composites. The finding of results indicated that the wear rate was decreased with the increase in the filler content in both the case of garnet and fly ash reinforced Al7075 hybrid composites. The results from Taguchi experiments suggested that the filler content and load were the most significant factors affecting wear behavior of composites while temperature and sliding distance are the least significant factors. Also, the garnet reinforced Al7075 hybrid composite indicated less specific wear rate as compared to that of fly ash reinforced Al7075 hybrid composite.     

Experimental correlations between wear rate and wear parameter of Al–Cu–Mg/bagasse ash particulate composite

The experimental correlations between wear rate and wear parameter of Al–Cu–Mg alloy composite reinforced with 10 wt.% bagasse ash particles produced by double stir casting method was developed in terms of applied load and sliding speed using the empirical linear regression and analysis of variance method. The wear behaviour of the specimen was investigated using pin-on-disc method. An empirical linear regression equation was used in predicting wear rate within a selected experimental domain. The predicted wear rate of the alloy and composite samples were found to lie close to that of the experimentally observed ones. The confirmation of experiments was conducted using analysis of variance (ANOVA) to verify the optimal testing parameters. The interactions of applied load and sliding speed of the composite had no significant effect, while the alloy had a significant effect on the wear rate.