Dry Sliding Wear Behavior of Aluminum-Based Metal Matrix Composites with Single (Al2O3) and Hybrid (Al2O3

Dry sliding wear behavior of 6351 Al alloy and its composites with single (Al2O3) and hybrid (Al2O3 + SiC) reinforcements was investigated at low sliding speed (1 m s(-1)) against a hardened EN 31 disk at different loads. In general, the wear mechanism involved adhesion and microcutting abrasion at lower load. At higher load, abrasive wear involving microcutting and microplowing along with oxide formation was observed. The 6351 Al-4 vol% Al2O3 composite exhibited superior wear resistance than 6351 Al alloy at all loads. This was attributed to the presence of massive Al2O3 particle clusters (that resisted the abrasive wear) and the formation of adherent massive tribo- oxide under higher frictional heat and associated temperature rise at higher load. The existing Al2O3 particles in a cluster acted as active nucleation sites for oxidation. At lower loads (viz. 19.6 and 29.4 N), 6351 Al-(2 vol% SiC + 2 vol% Al2O3) hybrid composite exhibited the best wear resistance due to the presence of massive (SiC + Al2O3) particle clusters resisting abrasive wear. However, at higher loads (39.2 and 63.8 N), the breakdown of (SiC + Al2O3) particle clusters resulted in a wear resistance of hybrid composite equivalent to (at 39.2 N) or much inferior to (at 63.8 N) that of 6351 Al alloy.