DISCONTINUOUSLY REINFORCED ALUMINUM COMPOSITES SLIDING AGAINST STEEL - STUDY ON WEAR BEHAVIOR

The microstructural and technological characteristics of metal matrix composites can be tailored if the role played by typical reinforcement parameters (type, shape, and volume fraction) is correctly evaluated. The present work used commercially pure Al reinforced with ceramic particles (Al2O3, SiC), manufactured via powder metallurgy and hot extruded. The volume fraction of reinforcement ranged from 5 to 15%. Dry sliding tests were performed on the composites using a flat on cylinder tribometer and the friction coefficient versus sliding distance was recorded. The counterface was a carbon steel cylinder treated up to a Rockwell hardness of 60 HRC. The microstructure of the worn surfaces of the composites was evaluated via light microscopy, scanning electron microscopy, and transmission electron microscopy. The wear behaviour and microstructural evolution of all materials including the unreinforced matrix, were related to both reinforcement variables and testing conditions. Using wear mechanism mapping, some guidelines for designing and selecting wear resistant composites are suggested.