Tribo-Mechanical Behaviour of Al-Cu-Si castings

Al-Cu-Si alloy of 1.5% copper and 0.5% silicon was sand casted into ingot rods with Nitrogen degassing. The sand casted rods were homogenized at different temperatures for a time of 10 hours. The homogenized and as cast rods were then tested for mechanical and tribological properties by taking samples from different regions surface, middle and inner regions respectively. The Microhardness, microstructure, Ultimate tensile strength(UTS), elongation in percentage (%), rate of wear and specific wear rate were determined and investigated. The results show improved mechanical and tribological properties of homogenized compared to as cast. The hardness and tensile strength values showed similar pattern of decrease from outer to middle to inner regions whereas elongation in percentage showed the opposite. The greater hardness and tensile strength at the outer surface can be attributed to the faster solidification (or higher cooling rate at the surface) compared to the slower cooling rate at inner region of ingot. Microstructure examination also revealed finer grains at inner The Adhesive wear properties were determined using Pin on Disc wear tester as per ASTME standards of dry sliding friction condition. The results showed adhesive dry Adhesive wear is carried out by Pin-on-Disc wear tester. Wear rate of the alloy rises with applied load conducted at different speeds. The specific wear rate and the friction coefficient vary with load. The diffusion of disc material into the specimen material which changes the alloy composition. It was observed through energy dispersive X-ray spectroscopy (EDX) analysis. The worn-out surfaces were studied by using SEM analysis.