Oxidation and Crack Healing Behavior of a Fine-Grained Cr2AlC Ceramic

This work reports the oxidation and crack healing behavior of a fine-grained (similar to 2m) Cr2AlC MAX phase ceramic. The oxidation behavior was investigated in the temperature range 900 degrees C1200 degrees C for times up to 100h. The material showed a good oxidation resistance, owing to the formation of a dense and thin -Al2O3 layer. The microstructure, composition and thickness of the oxide scale were characterized. Its oxidative crack healing behavior as a function of temperature, healing time, and initial crack size was studied systematically. The material showed excellent healing behavior. The main crack healing mechanism is the filling of the crack by oxides well adhering to the crack faces. The crack geometry before and after healing was characterized by X-ray tomography. Three-point bend tests showed the dependence of strength recovery at 1100 degrees C as a function of initial crack length and healing time.