Sintered 6061 Aluminium Alloy Solid Lubricant Particle Composites: - Sliding Wear and Mechanisms of Lubrication

Abstract

Aluminium alloy (6061) matrix composites containing up to 14 vol.% natural graphite particle dispersions were prepared by a powder metallurgy route. Dry sliding wear rates of composites were evaluated against a rotating EN25 steel disc using a pin-on-disc apparatus. Worn surfaces and debris were examined in the scanning electron microscope. Model experiments were conducted on the etched surfaces of a 6061 aluminium alloy-14 vol.% graphite composite with graphite particle protrusions. Wear rates of composites increased linearly with the graphite volume fraction. Worn surfaces did not reveal the presence of a graphite film and the majority of debris were flaky in nature. This anomalous behaviour with graphite was attributed to the increased porosity (interconnected and interfacial) in the composites. Wear rates of composites in the etched condition showed a substantial decrease over that of the matrix alloy. Worn surfaces of composites in this case showed patches of graphite layers adhering to them.