Friction and wear properties of mullite/ZrO₂/Al₂O₃ composites

The friction and wear properties of ZrO₂ and Al₂O₃ cooperatively toughened mullite composites - mullite/ZrO₂/Al₂O₃ (MZA) were studied. The tribological tests were performed in a line-reciprocating tribometer using a GCr15 steel ball on a MZA disk under different dry reciprocating sliding conditions at room temperature. A wide range of normal loads and sliding speeds were chosen to investigate the relationship between the wear mechanisms of MZA and the testing conditions. The wear mechanism diagram of MZA is constructed, and it contains two typical regions. It suggests that the wear mechanisms of MZA in each of the region change from one to another depending on the wear conditions. In the mild wear region, the wear rate of MZA is 10^-6 mm³/m, and the wear mechanism of MZA is plastic deformation accompanied by a little micro-cracking. In the severe wear region, the wear rate of MZA is 10^-5 mm³/m and the dominant wear mechanism in this region is brittle fracture.