Enhanced thermal shock resistance of ZrO2-reinforced Al2O3–CaAl12O19 composites prepared from ferrotitanium slag: Crack propagation resistance mechanisms

Abstract

Al2O3–CaAl12O19 composites are ideal high-temperature structural ceramics, however, their poor thermal shock resistance limits their application under thermal shock conditions. In this work, ferrotitanium slag was used as the main raw material for composites preparation. Enhanced thermal shock resistance were obtained by adding 12.5 wt.% unstabilized monoclinic zirconia. A systematic analysis of the phase compositions and microstructural evolution with particular attention to crack propagation was performed. The improvement in thermal shock resistance is attributed to the enhanced crack propagation resistance. Furthermore, the enhanced crack propagation resistance is caused by multiple mechanisms, including the t-ZrO2-related stress-induced t → m phase transformation mechanism and the m-ZrO2-related microcracking mechanism. Coarsened ZrO2 particles doped with TiO2 from the ferrotitanium slag are beneficial to the occurrences of stress-induced transformation and microcracking.