The effect of heat treatment on the wear behaviour of graphite and SiC reinforced ZA 27 hybrid composides

Key Words: Zinc-Aluminum alloys, ZA-27, Metal Matrix Composites, Heat Treatment, Micro Structure, Wear and FrictionThe aim of study is to enhance the wear behavior of ZA-27 alloy, 2.5-5-7.5-10 % graphite reinforced composites (GRC), 10 % SiC reinforced composites (SRC), 10 % SiC and 2.5-5-7.5-10 % graphite reinforced hybrid composite materials (HCM) via heat treatment techniques.The microstructural changes after casting and heat treatment processes were investigated via optical microscopy and scanning electron microscopy techniques. A homogenous microstructure was obtained after heat treatment processes.Brinell (HB) and Wickers (HV) hardness test methods were used for the samples produced via casting and heat treatment processes. It was found that the hardness values of the composites were increased with increasing graphite reinforcement till to 5 % while decreased with increasing graphite reinforcement till to 7.5 % and 10 %.Wear tests were performed under 5 N load, within a distance of 500 m and by using 0.5, 1 and 2 m/s via pin on disc methods. The changes in the friction coefficient and mass losses were measured for the samples produced by casting and heat treatment processes. The worn surfaces of the composites were also investigated via scanning electron microscopy techniques. It was found that mass losses were decreased after reinforcing the zinc-aluminum alloy with graphite, SiC and SiC + graphite. The minimum mass losses were obtained with 10% SiC + 7.5 % and 10 % SiC + 10 % graphite reinforced composites. It was also found that the friction coefficient of the composites were increased with increasing SiC reinforcing while decreased with increasing graphite reinforcing.