Crack patterns corresponding to the residual strength plateau of ceramics subjected to thermal shock

Abstract

The formation mechanism of the residual strength plateau of ceramics subjected to thermal shock is addressed. A set of thermal shock experiments of 99Al2O3 are conducted, where the thin specimens of 1 mm×10 mm×50 mm exhibit parallel through edge cracks, and thus permit quantitative measurements of the crack patterns. The cracks evolve with the severity of thermal shock. It is found that there is a correlation between the length and density of the thermal shock cracks. The increase of crack length weakens the residual strength, whereas the increase of crack density improves it. In a considerably wide temperature range, the two contrary effects just counteract each other; consequently a plateau appears in the variation curve of the residual strength. A comparison between the numerical and experimental results of the residual strength is made, and they are found in good agreement. This work is helpful to a deep understanding of the thermal shock failure of ceramics.