DRY SLIDING WEAR BEHAVIOR OF AL-2,O-3 AL COMPOSITES PRODUCED BY CENTRIFUGAL FORCE INFILTRATION

The drying wear and friction behaviour of cast Al-Si alloy and composi tes containing 5.0, 8.0, 12.0, and 16.0 vol.-% alumina short fibres wa s investigated by means of a block on ring (bearing steel) type wear r ig. 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 squeez e 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 we ar rate regime which occurred in an unreinforced Al-Si alloy in the lo ad range of 100-150 N. The coefficient of friction of the composites w as higher than that of the unreinforced Al-Si alloy at applied loads b elow 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 i ncreasing applied loads, and it can reach 520 K at a load of 150 N. Ex amination of the worn surfaces by SEM identified that the presence of alumina fibres suppressed the transition to the severe wear rate regim e. (C) 1996 The Institute of Materials.