Influence of SiC and Al2O3 Particulate Reinforcements on Metal-Metal Wear Behavior of Al6061 Alloy Hybrid Composites Produced by Stir Casting Method

Dry sliding metal-metal wear behavior of Al6061 alloy, discontinuously reinforced with fine particles of SiC and Al₂O₃ are presented and discussed this paper. The discontinuously reinforced aluminum (DRA) alloy composites with 5-25% volume fractions of SiC and Al₂O₃ particulates were produced by stir casting method and using them test specimens were prepared. The dry sliding behavior of these  hybrid composite specimens and that of Al6061 unreinforced alloy at room temperature was investigated by using pin-on-disk wear testing machine over a load range of 29.43N-49.05N (3-5 kgf) for a total sliding distance of 1413m  at a constant sliding speed of 1.57m/s. The results show that, the reinforcement of the metal matrix with SiC and Al₂O₃ particulates upto a volume fraction of 25% reduces the wear rate at room temperature. Higher the volume fraction of the reinforcements lower was the rate of wear. The results also show that the wear of test specimens increase with increasing load and sliding distance. Also micro hardness of the specimens at the room temperature was measured before and after the wear tests by Vickers hardness testing machine.  The micro hardness of the hybrid composite test specimens increases with increasing volume fraction of particulates reinforcement. The optical micrographs taken for the micro structure analysis of the hybrid composite specimens show that the SiC and Al₂O₃ particulates are uniformly distributed in the matrix. It was also found from the optical micrographs that the porosity of the test specimens increases with the increasing volume fraction of particulate reinforcement. The wear surfaces were examined by scanning electron microscopy, which showed that the wear surface of the composite alloy was generally much rougher than that of the unreinforced alloy. Large grooved regions and cavities with ceramic particles were found on the worn surface of the composite alloy. This indicates an abrasive wear mechanism which is essentially a result of hard ceramic particles exposed on the worn surface.