Effect of extrusion ratio on wear behaviour of hot extruded Al6061-SiCp (Ni-P coated) composites

Metallic coated reinforcements are currently gaining popularity as regards processing of high quality metal matrix composites (MMCs) by liquid metallurgy route. The major reasons being improvement of wettability between reinforcement and molten alloy and to eliminate interfacial reactions. Both these factors lead to inferior mechanical and tribological properties of developed MMCs with non uniform distribution of reinforcement. In the light of the above, the present work focuses on development of Al6061-SiCp (Ni-P coated) composites by stir casting followed by hot extrusion using 200T hydraulic press at a temperature of 550 degrees C under different extrusion ratios. Extrusion ratios of 1:4, 1:5, 1:10 and 1:15.5 were adopted. Microstructure studies microhardness, tensile strength tests were conducted on hot extruded composites. Pin-on-disk wear tests were carried out at different loads and sliding velocities for the extruded composites at different extrusion ratios. SEM of worn surfaces was also carried out. As the extrusion ratio increases, microhardness and tensile strength of the composites increased. Further, under all the wear tests conditions studied, the wear resistance of the hot extruded MMCs was superior for the highest extrusion ratio studied. (C) 2011 Elsevier B.V. All rights reserved.