Effect of tremolite on the mechanical properties and thermal shock resistance of Al₂O₃ composites fabricated by temperature gradient spark plasma sintering

Abstract

Al2O3 has received increasing attention in the field of cutting tools and structural ceramics owing to its good mechanical performance. The mechanical and thermodynamic properties of Al2O3 matrix composites prepared by temperature gradient spark plasma sintering were investigated in this study. Liquid-phase sintering was confirmed to have occurred, based on thermodynamics and X-ray diffraction analysis during the fabrication of the Al2O3 composites. By dynamically modifying the heating rate during the entire preparation process, Al2O3 composites with smaller grain sizes were obtained. The effect of the tremolite additive on the hardness of the Al2O3 composites was elucidated by comprehensively considering the hardness and densification effects. The microstructural evolution of the composites was analyzed. The critical crack length was considered as the parameter necessary to evaluate the thermal shock resistance of the Al2O3 composites. The crack propagation resistance was found to significantly affect the thermal shock resistance of the Al2O3 composites. The results showed that the thermal shock resistance of the Al2O3 composites improved owing to the decrease in porosity and the improvement in mechanical properties due to the addition of tremolite.