Dry sliding wear behaviour of Al-2,O-3 Al composites produced by centrifugal force infiltration

The drying wear and friction behaviour of cast Al-Si alloy and composites containing 5.0, 8.0, 12.0, and 16.0 vol.-% alumina short fibres was investigated by means of a block on ring (bearing steel) type wear rig. The volume wear rate, the coefficient of friction, and the contact surface temperature of both matrix alloy and metal matrix composites (MMCs) were measured over a load range of 20-150 N for various sliding distances. Comparisons were made between the wear properties of MMCs produced by the centrifugal force infiltration route and by the squeeze infiltration method. The experimental results show that the addition of reinforcing alumina fibre in Al-Si alloy not only reduced the wear rate, but also effectively suppressed the transition to the severe wear rate regime which occurred in an unreinforced Al-Si alloy in the load range of 100-150 N. The coefficient of friction of the composites was higher than that of the unreinforced Al-Si alloy at applied loads below 100 N, but there was almost no difference above 100 N with a mean value of about 0.40. The contact surface temperature increases with increasing applied loads, and it can reach 520 K at a load of 150 N. Examination of the worn surfaces by SEM identified that the presence of alumina fibres suppressed the transition to the severe wear rate regime. (C) 1996 The Institute of Materials.