DRY SLIDING WEAR OF AN ALUMINA SHORT-FIBER-REINFORCED AL-SI ALLOY AGAINST STEEL

Dry sliding wear tests were carried out on an unreinforced Al-12%Si al loy and on composites of the same alloy reinforced with 5, 8, or 12 vo l.% short alumina fibres by means of a block-on-ring (bearing steel) w ear test machine. The worn surfaces and cross-sections through the sur faces were examined by optical microscopy and by scanning electron mic roscopy. It was found that above a critical applied load, there exists a transition to severe wear both in the unreinforced Al-Si alloy and in the composites, but the transition loads for composites are much hi gher than that of the unreinforced alloy, and increase with increasing the volume fraction of alumina fibre. It is also discovered experimen tally that the presence of alumina fibres in the composites impedes th e formation of a fragmented layer and hence improves the wear resistan ce at high loads.