Dry sliding wear behaviour of Al(Mg)/Al2O3 interpenetrating composites produced by a pressureless infiltration technique

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 Al2O3 foams were pressurelessly infiltrated using an Al–8 wt.% Mg alloy. The wear rates of the alloy and the Al(Mg)/Al2O3 interpenetrating composites were tested under dry sliding conditions; effects of Al2O3 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 Al2O3 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.