Oxidation‐induced crack‐healing behavior of SiC‐Al2O3‐TiB2 composites at 600°C–800°C

Abstract

ABSTRACTIt is necessary to give self‐healing function to ceramic materials because of their notch sensitivity. In the past, studies on self‐healing ceramics have mainly focused on the high‐temperature stage, and less research has been done below 1000°C. In this study, SiC/Al2O3/TiB2 ceramic composites were prepared by spark plasma discharge sintering, and cracks were introduced on the surface of the polished specimens. Crack healing at 600°C–800°C was investigated, and the recovery of macroscopic bending strength and the change of microscopic crack morphology after heat treatment were used to evaluate the crack‐healing effect. It was found that the surface cracks of the material were completely filled and healed by oxidation products after heat treatment at 700°C for 60 min, and the highest healing efficiency exceeded 95% for both specimens with different crack lengths, and the main mechanism of crack by Si‐Al‐B‐Na‐Ca‐O type glass produced by the reaction of TiB2 and a small amount of SiC with oxygen to produce oxides and glass powder. Good healing effect and fast healing speed effectively improve the service life and reliability of ceramic materials, which has very far‐reaching significance for the practical application with ceramic materials.