Tribological behaviour of AA2024 alloy reinforced with SiC and graphite hybrid composite by powder metallurgy route

Abstract

Aluminium metal matrix composites are a class of advanced materials newlinewhich have been developed for weight-critical applications in the aerospace and newlineautomotive industries. The present investigation aims to establish the tribological newlinebehaviour of aluminium-based graphite (Gr) and slicon carbide (SiC) particlereinforced newlinemicro- (40 to 100 m particle size) and nano- (50 to 100 nm particle newlinesize) composites manufactured (using ball mill) by powder metallurgy was studied newlineusing a pin-on- disk apparatus under dry sliding conditions. The pins made of these newlinecomposites were then slid against a steel disk under ambient conditions. The newlinesintered samples have been characterized by X-ray diffraction (XRD). The worn newlinesurfaces of the pins and wear debris were analyzed using a Scanning Electron newlineMicroscope (SEM). newlineIn micro composites, the results of the tests revealed that the SiCreinforced newlinehybrid composites exhibited a lower wear loss compared to the newlineunreinforced alloy and Al Gr composites. It was found that with an increase in the newlineSiC content, the wear resistance increased monotonically with hardness. The newlinehybridisation of the two reinforcements also improved the wear resistance of the newlinecomposites, especially under high sliding speeds. Additionally, the wear loss of the newlinehybrid composites decreased with increasing applied load and sliding distance, and a newlinelow friction coefficient and low wear loss were achieved at high sliding speeds. The newlinecomposite with 5 wt.% Gr and 20 wt.% SiC showed the greatest improvement in newlinetribological performance. The wear mechanisms in micro composites was dictated newlineby the formation of both a delamination layer and mechanically mixed layer newline(MML).Analysis of variance (ANOVA) was used to investigate the influence of the newlineparameters on both the wear loss and the coefficient of friction. The hardness of the newlinemicro composites decreases as the % of graphite increases. newline newline