Severe wear mechanisms in Al2O3-AlON ceramic composites

Severe wear mechanisms in Al2O3-AlON ceramic composites during their fricti on against a bearing steel were investigated and analysed by different tech niques, mainly transmission electron microscopy (TEM). It was shown that ce ramic damages correspond not to a classical intergranular cracking but to a breakdown of alumina-alumina grain boundaries leading to their pull off. C onsequently, a new model of the severe wear of ceramics, based on a dielect ric approach is proposed. Moreover, the existence of AlON located at such b oundaries induces a delaying effect of this damage and seems to participate in the forming and the stability in the contact of a third body essentiall y constituted by iron oxides. (C) 2000 Elsevier Science Ltd. All rights res erved.