Characterization of Al-12Si alloy and its composites in dry sliding friction and wear at elevated temperature

Al-12Si alloy matrix composites reinforced with Al2O3 and carbon fibers respectively as well as with the two fibres were fabricated by squeeze-infiltration. The elevated temperature (about 400 degreesC) friction and wear behaviors of Al-12Si alloy and its composites were investigated. The results show that the hybrid composites reinforced. with Al2O3 and carbon fibres are of superior high temperature wear resistance. The critical transition temperature from mild wear to severe wear of the composites reinforced only with Al2O3 fiber is improved markedly compared with monolithic Al-12Si allot, from 200 degreesC to 300 degreesC. However, the critical transition temperature of the hybrid composites reinforced with Al2O3 and carbon fibers is improved further to 400 degreesC. The reinforcing fibers have no significant effect on wear mechanisms of Al-12Si alloy. The dominant mechanisms are ploughing grooves and delamination as well as slight adhesion during mild wear regime. The subsurface consists of three regions: non-peeling delamination layer, microcrack formation and propagation zone, and unaffected zone. Whereas the dominant mechanism is shifted to severe wear when test temperature exceeds the critical transition temperature.