Effect of ZrO2 on microstructure and wear properties of Al2O3/Al–Si composites

Abstract

This study has investigated the dry sliding wear behaviour of aluminium (Al)–silicon (Si) alloy matrix hybrid composites reinforced with nanosized alumina (Al2O3) and zirconia (ZrO2) in cast and heat-treated conditions. Dry sliding wear tests were performed on a pin-on-disc apparatus under a normal load of 10 N. Optical microscopy, X-ray diffraction and scanning electron microscopy examination were used to investigate the microstructures and tribological properties of the composites and the base alloy. For comparison of the wear behaviours of the samples, the wear constant (K) was measured based on the wear rate data. The lowest wear constant was observed in the heat-treated composite containing 2 wt.% zirconia, which shows a decrease of around 65% in comparison to the non-reinforced base alloy. It has been suggested that the wear process is controlled by nucleation and propagation of cracks; however, in the case of heat-treated composites, the fragmentation of layers decreases due to the spherical nature of silicon particles.