Tribological properties of compocasted A356 aluminium alloy composite reinforced with Al 2O 3, SiC and graphite particles

Abstract

Particulate composites with A356 aluminium alloy as a matrix were produced by compocasting process using ceramic particles (Al 2O 3, SiC) and graphite particles. The matrix alloy and the composites were thermally processed applying the T6 heat treatment regime. Hardness and tribological properties of heat treated matrix alloy and composites were examined and compared. Tribological tests were carried out on pin-on-disc tribometer under dry sliding conditions. Sliding was linear (reciprocating). Counter body was alumina ball. Maximum velocity was 0.06 m/s, sliding distance was 500 m and normal load was 1 N. Wear resistance of the composites reinforced with SiC particles was higher and coefficient of friction was lower compared to the composite reinforced with Al 2O 3 particles due to the higher hardness of the SiC particles, and due to the fact that the SiC reinforcements were protruded to the surface and thus protect the matrix alloy from further wear. Addition of graphite particles (1 wt. %) to the composite with SiC particles further reduced the wear rate and the coefficient of friction.