Tribological behavior of Al-based self-lubricating composites

Aluminum-based composites containing either SiC (Al10%SiC) as the hard phase or a combination of SiC and MoS2 (Al10%SiC4%MoS2) have been synthesized following stir casting route. To overcome the poor wetting characteristics, magnesium was added in one of the composites (Al10%SiC4%MoS24%Mg) to improve the bonding between matrix and second phase. The results suggested an enhancement in hardness and strength of the composite containing SiC–MoS2 and Mg, thus indicating the effectiveness of Mg addition in improving the interfacial bonding strength. Tribological performance of the composites has been examined by carrying out pin-on-disk wear tests under dry sliding conditions at different normal loads of 9.8, 14.7, 19.6, and 24.5 N and at a constant sliding speed of 1 m/s. Both the friction coefficient and the wear rate have been found to reduce with addition of MoS2; however, bonding between the matrix and reinforcements was not good. Al10%SiC4%MoS24%Mg has shown the best tribological performance at all the loads in terms of the lowest friction coefficient and the lowest wear rate. The wear mechanism has been found to be a combination of adhesion and abrasion as indicated by the presence of some abrasive grooves and delaminated flakes at the worn surface and the X-ray examination of wear debris for all the materials used in the present investigation.