Effects of β-Si3N4 whiskers addition on mechanical properties and tribological behaviors of Al matrix composites

Abstract

β-Si3N4 whiskers reinforced Al matrix composites were prepared by hot pressing. The effect of β-Si3N4 whiskers addition on the microstructure, mechanical properties and tribological behaviors of composites were investigated. The dry sliding wear test was conducted with a sliding speed of 0.5 m/s, at different applied load of 10, 20 and 40 N, respectively. The Vickers hardness, ultimate compression strength (UCS) and the wear resistance of Al matrix were enhanced significantly with the addition of whiskers. As the increase in whisker content, there was a clear transfer of wear mechanism from the combination of serious delamination wear and abrasive wear to the mild abrasive wear at the 20 N applied load condition. The composites reinforced with 15 vol% whiskers exhibited the best wear resistance under higher applied load. The mechanically mixed layer (MML) formed during sliding had a protective effect on the worn surface. Higher mechanical properties of composites and lower applied load helped to keep the MML stable. The slighter the wear degree of composites is, the lower the coefficient of friction is.