Effect of silicon carbide particulates on wear resistance of graphitic aluminium matrix composites

Use of graphite (Gr) reinforcement in aluminium matrix composites has been reported to be beneficial in reducing wear due to its solid lubricant property, but it results in reduction of mechanical strength. Addition of silicon carbide (SiC), on the other hand, improves both strength and wear resistance of composites, but high amount of SiC makes machining difficult and composites become brittle. Thus, SiC can be advantageously used as a second reinforcement to overcome the problem of strength reduction of Gr reinforced composites, resulting in what is known as hybrid composites. Aluminium matrix composites reinforced with equal weight fraction of SiC and Gr particulates up to 10% are studied with regard to hardness improvement and modified dry sliding wear behaviour. Studies based on design of experiments techniques indicate that there is an increasing trend of wear in Al–SiC–Gr hybrid composites beyond % reinforcement of 7.5%. Hybrid composites exhibit better wear characteristics compared to Gr reinforced composites. Interaction between load and sliding distance is noticed in both the composites and this may be attributed to the presence of Gr particulates. Decrease of wear with increase of speed and increase of wear with increase of either load or sliding distance or both were noticed.