The effects of graphite and SiC formation on mechanical and wear properties of aluminum-graphite (Al/Gr) composites

Aluminum-graphite (Al/Gr) composites were fabricated by a proposed technique called “ex-situ and in-situ powder metallurgy” to avoid an interfacial reaction between the graphite and the aluminum. In the present study, a cooled compact pressing of material powders followed by hot extrusion techniques were used. Varies weight percentages of graphite flakes were mixed with Al powder using a mechanical mixing stirrer. The effects of graphite content and SiC formation on microstructures and wear properties of composites were investigated. The SiC particles are formed by in-situ reaction at temperatures above 252°C. SiC particles have greatly improved the wear and tensile properties of fabricated composites. The results also showed the SiC particles were refined (< 1μm) and uniformly distributed in the matrices as a result of hot extrusions and little pores were found in the composites. This significantly improves mechanical and wear properties.