Wear behaviour of single phase and composite sialon ceramics stabilized with Y2O3 and Lu2O3

The wear properties of single phase α and two phase α/β composite sialon ceramics sintered with both yttria and lutetia have been studied under dry conditions using block on ring wear tests. Under high load conditions, where microcracking and grain pullout are the predominant wear modes the composite materials showed better wear properties than the single phase materials. Under low load wear, where tribochemical phenomena are thought to provide a major wear mechanism, the single phase materials showed better wear properties than the composites. Under these conditions there was a large effect of the stabilizing cation, with the Lu stabilized sample having a wear volume an order of magnitude lower than that of the Y stabilized one. The improved wear resistance of the Lu stabilized sample is attributed to the higher thermal stability of the sialon phase sintered with smaller cations and the more refractory nature of the residual grain boundary phase.