Severe wear mechanisms in Al2O3–AlON ceramic composites

Severe wear mechanisms in Al2O3-AlON ceramic composites during their friction against a bearing steel were investigated and analysed by different techniques, mainly transmission electron microscopy (TEM). It was shown that ceramic damages correspond not to a classical intergranular cracking but to a breakdown of alumina–alumina grain boundaries leading to their pull off. Consequently, a new model of the severe wear of ceramics, based on a dielectric approach is proposed. Moreover, the existence of AlON located at such boundaries induces a delaying effect of this damage and seems to participate in the forming and the stability in the contact of a third body essentially constituted by iron oxides.