Reducing the erosive wear rate of Cr₂AlC MAX phase ceramic by oxidative healing of local impact damage

Abstract

The present work describes a model study to explore the possibility to heal early stage erosion damage in Cr₂AlC MAX phase when exposed to high air temperatures and erosive conditions. Such a healing reaction should lead to a reduction of the wear rate of this promising material for application in jet turbine engines. To this aim Cr₂AlC ceramic disks were subjected to room temperature erosion for 60 min using glass microbeads accelerated to 110 m/s and impinging perpendicular to the sample surface. After the usual incubation time, the erosion rate reaches a constant rate, which is associated with the formation of network of small cracks underneath the surface. Next, the material was annealed at 1200 °C for 10 min in air resulting in filling of the network of small cracks due to the formation of well-adhering Al₂O₃. The subsequent erosion rate of the healed Cr₂AlC ceramic at room temperature is drastically reduced. Once the healed zone is removed by erosion the erosion rate attained its original value. Clearly, exposure to high temperature oxidative conditions extends the lifetime of Cr₂AlC MAX phase components subjected to erosive conditions.