Orthogonal experimental design applied for wear characterization of aluminum/Csf metal composite fabricated by the thixomixing method (original) (raw)
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An Investigation on Wear Behavior of Graphite Reinforced Aluminum Metal Matrix Composites
2018
The present work investigates the 6061Al alloy – Graphite composite with graphite particle dispersions upto 9% to identify its potential to act as a self lubricating material at an optimum level of graphite. The required specimens are prepared using stir casting method with graphite proportions ranging from 3 to 9% by weight. Experiments were carried out to evaluate the tribological behavior of the composite material with varying graphite content in terms of coefficient of friction and wear rate. Under dry sliding conditions, effects of the sliding distance and sliding speed have also been studied. Under dry sliding conditions, minimum coefficient of friction and wear rate has been observed for 9% graphite content. Consequently 6061Al-graphite showed its capability to act adequately as a self lubricating material. Keywords—Aluminium-graphite MMC, Wear behavior, 6061Al-Graphite particulates, Coefficient of Friction
A study on wear behaviour of Al/6101/graphite composites
Journal of Asian Ceramic Societies, 2017
The current research work scrutinizes aluminium alloy 6101-graphite composites for their mechanical and tribological behaviour in dry sliding environments. The orthodox liquid casting technique had been used for the manufacturing of composite materials and imperilled to T6 heat treatment. The content of reinforcement particles was taken as 0, 4, 8, 12 and 16 wt.% of graphite to ascertain it is prospective as self-lubricating reinforcement in sliding wear environments. Hardness, tensile strength and flexural strength of cast Al6101 metal matrix and manufactured composites were evaluated. Hardness, tensile strength and flexural strength decreases with increasing volume fraction of graphite reinforcement as compared to cast Al6101 metal matrix. Wear tests were performed on pin on disc apparatus to assess the tribological behaviour of composites and to determine the optimum volume fraction of graphite for its minimum wear rate. Wear rate reduces with increase in graphite volume fraction and minimum wear rate was attained at 4 wt.% graphite. The wear was found to decrease with increase in sliding distance. The average coefficient of friction also reduces with graphite addition and its minimum value was found to be at 4 wt.% graphite. The worn surfaces of wear specimens were studied through scanning electron microscopy. The occurrence of 4 wt.% of graphite reinforcement in the composites can reveal loftier wear possessions as compared to cast Al6101 metal matrix.
Wear properties of graphene-reinforced aluminium metal matrix composite: A review
Reviews on Advanced Materials Science, 2023
The recent advancement in graphene-reinforced aluminium matrix composites improves wear behaviour in the production of lightweight and high-performance nanocomposites. Considerable works have been devoted to using graphene nanoparticles as solid self-lubricants to increase wear resistance, minimise friction coefficients, improve service efficiency, and extend the lifespan of related sliding components. In general, wear behaviour often depends on the homogeneous distribution of graphene in the aluminium matrix. The non-uniform distribution of reinforcement due to the tendency of graphene to agglomerate in aluminium matrix and its poor wettability becomes a challenge in developing optimum functional of composites. The wettability of graphene can be enhanced by proper processing methods and sufficient addition of magnesium that can improve the wear and frictional properties of the produced composites. Hence, this review article provides recent findings and the influence of graphene as reinforcement materials in composites, including the effects on wear behaviour and friction properties. This article also discusses new advancements in the effect of graphene in self-lubricating aluminium matrix composites and the impact of reinforcement on the wear mechanisms of the composites. The future direction of the wear properties of MMCs is also covered at the end of the review.
Application of factorial techniques to study the wear of Al hybrid composites with graphite addition
The wear and sliding friction response of a hybrid aluminium metal matrix composite reinforced with hard ceramic (5 wt.% of SiC) and soft solid lubricant (0, 5, and 10 wt.% of graphite) fabricated by powder metallurgy was investigated. The influence of the percentages of reinforcement, load, sliding speed and sliding distance on both the wear and friction coefficient were studied using the pin-on-disk method with tests based on the design of experiments. Analysis of variance (ANOVA) was used to investigate the influence of the parameters on both the wear rate and the coefficient of friction. The hardness of the composites decreases as the % of graphite (Gr) increases. The wear and friction coefficient were mainly influenced by both the sliding distance and the load applied. The morphology of the worn out surfaces and the wear debris was analysed to understand the wear mechanisms. The wear resistance of the hybrid composite containing 5 wt.% SiC and 5 wt.% graphite is superior to that of the graphite free composites and the other hybrid composites. This study reveals that the addition of both hard reinforcement like SiC and soft reinforcement like graphite improves the wear resistance of aluminium composites significantly.
Wear, 2009
The influence of graphite content on the dry sliding and oil impregnated sliding wear characteristics of sintered aluminum 2024 alloy-graphite (Al/Gr) composite materials has been assessed using a pin-ondisc wear test. The composites with 5-20 wt.% flake graphite particles were processed by in situ powder metallurgy technique. For comparison, compacts of the base alloy were made under the same consolidation processing applied for Al/Gr composites. The hardness of the sintered materials was measured using Brinell hardness tester and their bending strength was measured by three-point bending tests. Scanning electron microscopy (SEM) was used to analyze the debris, wear surfaces and fracture surfaces of samples. It was found that an increase in graphite content reduced the coefficient of friction for both dry and oil impregnated sliding, but this effect was more pronounced in dry sliding. Hardness and fracture toughness of composites decreased with increasing graphite content. In dry sliding, a marked transition from mild to severe wear was identified for the base alloy and composites. The transition load increased with graphite content due to the increased amount of released graphite detected on the wear surfaces. The wear rates for both dry and oil impregnated sliding were dependent upon graphite content in the alloy. In both cases, Al/Gr composites containing 5 wt.% graphite exhibited superior wear properties over the base alloy, whereas at higher graphite addition levels a complete reversal in the wear behavior was observed. The wear rate of the oil impregnated Al/Gr composites containing 10 wt.% or more graphite particles were higher than that of the base alloy. These observations were rationalized in terms of the graphite content in the Al/Gr composites which resulted in the variations of the mechanical properties together with formation and retention of the solid lubricating film on the dry and/or oil impregnated sliding surfaces.
Wear, 2010
Sintered polyimide/graphite composite cylinders were worn in a macroscale line-on-plate contact at different temperatures, revealing instable and relatively high coefficients of friction at 23 < T < 100 • C, decreasing coefficients of friction at 100 < T < 180 • C and constant values for coefficients of friction at 180 < T < 260 • C. The tendencies correspond with a transition from low wear rates at 23 < T < 100 • C into high and stable wear rates at 180 < T < 260 • C. These observations suggest that the lubricating effect of graphite does not prevail at all temperatures. Contact-mode atomic force microscopy of the worn surfaces was used for getting insight in the sliding processes at a micro-to nanoscale. The friction signals provide insight in the local distribution of the composite phases over the surface. Selection criterions for surface patterns representing optical interferences or shear banding patterns, were based on fast Fourier transform images. At low temperatures, severe wear grooves and shear bands within the graphite phase indicate the abrasiveness of graphite additives together with inhomogeneous graphitic transfer onto the polyimide surface areas. At intermediate temperatures, a very thin and discontinuous graphite film forms while the imide zones show a finely structured surface with homogeneous mixture of polyimide grains and graphitic particles. At high temperatures, the surfaces are relatively smooth and homogeneous with a thin graphite film covering the entire surface. The relation between coefficients of friction and surface morphology is most significantly quantified in the evolution of roughness parameters determined from AFM scans.
Effect of Graphite Content on Tribological behaviour of Aluminium alloy - Graphite Composite
Euro Journals
An attempt has been made to study the influence of operating parameters such as applied load, sliding speed, percentage of reinforcement content and sliding distance on the dry sliding wear of 6061 aluminium with SiC and B4C particulate reinforced composite. The particulate reinforced 6061 aluminium alloy with a constant weight percentage of B4C particulate and varying range of SiC particulate is produced by stir casting technique. In order to achieve good binding between the matrix and particulates, 1% of magnesium alloy is added. Under dry condition the hybrid composite performances were investigated by pinon-disc with varying load conditions. The uniform distribution of particulates reinforced in the matrix was examined with the help of Optical-Microscope. The wear surfaces of the specimen at room temperature were examined before and after the wear test by using Scanning Electron Microscope (SEM). The hardness of the specimen at room temperature was also measured before the wear test by Rockwell hardness test machine. As the volume fraction of SiC and B4C reinforcement increases, the magnitude of hardness also increases. This investigation overviews that 6061 hybrid composite with high hardness can replace the conventional material used in automobile components for better performance and longer life.
Wear behavior of electroconductive graphene/alumina composite
2014
In the last few years, graphene has emerged as a promising reinforcement material to improve wear resistance in composite materials. Although there are many research articles in the graphene/polymer composite field, there are only a few examples in the literature where the tribological properties of graphene/ceramic composites have been analysed (1,2). The present work has studied, for the first time, to the best of our knowledge, the dry sliding behaviour of an alumina/graphene composite (3) against alumina in air. Under the adopted testing conditions, the reduction in the wear rate of almost twice the alumina value was observed once the graphene platelets were added to the monolithic material. Additionally, it was appreciated a reduction of the friction coefficient of about 10% that was attributed to the presence of the graphene platelets and the role that they play in the tribological system. These adhered platelets act as a self-lubricating layer when fixed to the contact surface between the composite and the alumina ball, during the experiment, that acts as counterpart material
TRIBOLOGY AND DEVELOPMENT OF WEAR THEORY: REVIEW AND DISCUSSION
In this review, the classical and contemporary wear theories and wear mechanisms are discussed. The development of wear theories are started from adhesive and abrasive to delamination theory, mechanical mixed layer (MML) and self lubrication theory are reviewed based on the previous reports. It was found that the adhesive and abrasive are developed based on quantitative approach whereas the delamination, MML and self lubrication theory are developed based on qualitative approach. Each theory has limitation in order to explain the wear theory comprehensively because of different testing system, composite manufacturing technique, type of reinforcement and volume fraction, size as well as hardness. However, a consensus has been reach from a qualitative point view. Theory of wear debris generation mechanism is the consequence of a combination of subsurface, surface and third body dynamic behaviours. This approach applied in order to explain the wear mechanism usually encountered such as adhesive, two-body abrasive, three-body abrasive, oxidation and delamination. Wear mechanism that occurred during dry siding wear of hybrid composite (multiple reinforcement composite consist of combination of hard and soft reinforcement) is combination of various mechanism and highly complex phenomenon. It well known that wear is nature process that what happen at one time is function of all event that occurred previously. Therefore, based on previous work on dry sliding wear of multiple reinforcement composite, it might be proposed that the wear mechanism involved in integrated wear mechanism.
Materials & Design, 1997
During the sliding of aluminium alloys dispersed with graphite particulates, a layer of graphite is usually present at the sliding interface. This tribo-layer significantly reduces the amount of direct metal-to-metal contact, giving rise to low friction and a low rate of wear, making these composites useful candidate materials for anti-friction applications. Such self-lubricating composites are commonly fabricated via the squeeze casting, slurry casting or powder metallurgy route. These processes are expensive while the less-expensive conventional casting route is limited by the agglomeration of graphite particles in the composites, giving rise to poor mechanical properties. In this work, graphite (particulate-reinforced Al᎐4.5 wt.% Cu composites with two effective graphite contents Al᎐4.5 Cu / 4.2) wt.% C and Al᎐4.5 Cu / 6.8 wt.% C were synthesized through an innovative partial liquid phase () casting rheocasting technique, which is a modification of the conventional casting process. Unlubri-() cated without the use of conventional liquid lubrication friction and wear performance of these composites as well as the un-reinforced aluminium alloy was determined using a pin-on-disk tester. The results revealed that the graphite-reinforced composites have a higher wear rate than the un-reinforced matrix alloy while their frictional characteristics are very similar within the range of testing conditions. Combining these with the information gathered from worn-surface examinations and wear-debris analysis, it is suggested that there exists a certain threshold for the amount and size of graphite particulates in these composites to enable them to have improved tribological properties.