Fabrication characteristics and tribological behavior of Al/SiC/Gr hybrid aluminum matrix composites: A review

Improvement in surface properties and retainment of bulk properties are essential requirements for the design of components for wear resistance applications. This paper summarizes various features of Al/SiC/Gr hybrid composites that can be employed in different tribological applications. The study has revealed that the processing route plays a significant role in obtaining a homogeneous structure of these composites. In powder metallurgy, the selection of sizes of the matrix and reinforcement powders is crucial, whereas the wettability between the reinforcement particles and molten alloy is a major challenge in liquid metallurgy. The incorporation of SiC particles increases the mechanical strength and wear performance of Al composites. However, ejection of these particles can reduce the wear performance of Al composites under severe conditions. The addition of Gr particles helps in the formation of a thick and extensive tribolayer on the wear surface. This layer reduces direct contact between the rubbing surfaces, thereby decreasing the wear rate under certain conditions. Morphological analysis of worn surfaces has confirmed that the hybrid composites exhibit superior wear properties than the pure Al alloy and the ceramic-reinforced composite. However, increase in the Gr content beyond a limiting value can deteriorate the tribological properties of these composites. Therefore, true optimization of a tribosystem (of the hybrid composite and counterface) can be achieved by selecting appropriate reinforcement contents.