Influence of the SiC grain size on the wear behaviour of Al2O3/SiC composites

Dry ceramic block-on-steel ring wear tests were performed at high loads in several Al2O3/20 vol.% SiC composites as a function of the SiC grain size, which ranged from 0.2 to 4.5 μm in d50. The wear resistance of the monolithic alumina was radically improved by the addition of the SiC particles, reducing down to one order of magnitude wear rate. Two different behaviours were identified according to the microstructural observations on the worm surfaces: intergranular fracture and grain pull-out in the monolithic Al2O3, and plastic deformation and surface polishing in the composites. The wear resistance of the Al2O3/SiC composites increased with the SiC grain size due to their fracture toughness enhancement.