Thermal shock behavior of porous Si3N4 ceramics with Nd2O3 as sintering additive

Abstract The thermal shock behavior of porous Si 3 N 4 ceramics with Nd 2 O 3 as sintering additive was investigated by the water quenching method in the temperature difference range from 200 to 1500°C. The porosity and residual flexural strength of the specimens after single water quenching were measured to reveal the influence of thermal shock on porous Si 3 N 4 ceramics. It was found that the critical temperature was 780°C, which was almost 230°C higher than its dense counterpart reported by other researchers. Scanning electron microscope was used to examine the microstructure evolution of the external surface and interior after water quenching. Surface oxidation and cracks formation were found to be the primary cause of the strength degradation of porous Si 3 N 4 ceramics. The phase composition variation in the surface was also characterized by X‐ray diffraction.