Friction and wear behavior of laser composite surfaced aluminium with silicon carbide

The present study concerns the wear behavior of laser composite surfaced Al with SiC and Al + SiC particulates. A thin layer of SiC and Al + SiC (at a ratio of 1:1 and dispersed in alcohol) were pre-deposited (thickness of 100 μm) on an Al substrate and laser irradiated using a high power continuous wave (CW) CO₂ laser. Irradiation leads to melting of the Al substrate with a part of the pre-deposited SiC layer, intermixing and followed by rapid solidification to form the composite layer on the surface. Following laser irradiation, a detailed characterization of the composite layer was undertaken in terms of microstructure, composition and phases. Mechanical properties like microhardness and wear resistance were evaluated in detail. The microstructure of the composite layer consists of a dispersion of partially melted SiC particles in grain refined Al matrix. Part of the SiC particles are dissociated into silicon and carbon leading to formation of the Al₄C₃ phase and free Si redistributed in the Al matrix. The volume fraction of SiC is maximum at the surface and decreases with depth. The microhardness of the surface improves by two to three times as compared to that of the as-received Al. A significant improvement in wear resistance in the composite surfaced Al is observed as compared to the as-received Al. The mechanism of wear for as-received vis-à-vis laser composite surfaced Al has been proposed.