Hot extruded Al5SiC-graphite composites: Effect of graphite on microstructure, flexural, compressive and wear resistance behavior

The Al5SiC and hybrid Al5SiC-graphite composites with 2 and 8 wt% of graphite were manufactured by a hot extrusion process. The starting material was in the form of powders. The effect of graphite on the microstructure, mechanical and tribological properties of Al5SiC composites was investigated. Extruded rods had a relative density greater than 97 %. The microstructure of hybrid composites was characterized by longitudinal stripes of reinforcement with its local agglomerations in the composite containing 8 wt% graphite. The Al5SiC composite exhibited the highest flexural strength (386 MPa) and compressive strength (642 MPa) and was distinguished by the lowest weight loss (0.00116 g). The addition of 8 wt% of graphite resulted in a significant deterioration of the flexural strength (269 MPa) and compressive strength (312 MPa) compared to the matrix material. The Al5SiC-8Cgr composite was characterized by the highest weight loss (0.01681 g) and the lowest friction coefficient (0.60) among tested materials.