Dry sliding wear behaviour of Al(Mg)/Al_2O_3 interpenetrating composites produced by a pressureless infiltration technique

摘要

Aluminium alloys, reinforced with ceramic particles or fibres, are desired materials in high performance applications due to their superior properties. In this paper, gel-cast Al_2O_3 foams were pressurelessly infiltrated using an Al-8 wt.% Mg alloy. The wear rates of the alloy and the Al(Mg)/Al_2O_3 interpenetrating composites were tested under dry sliding conditions; effects of Al_2O_3 foam density and cell size on the composite wear resistance under different loads and sliding distances were investigated. A 'ploughing' mechanism was observed in all the composites after an initial 250 m sliding distance, whilst the composites with the higher foam density show a 'two-stage' wear with sliding distance. The decrease in the wear rate in the second stage in the latter is attributed to an Al_2O_3 network protruding out of the worn surface, which protects the direct wear of the Al(Mg) alloy by the counter ball. Within the range studied, a larger cell size is preferred for better wear resistance.