Thermal shock behavior of ZrB₂--SiC ceramics with different quenching media

Abstract

The thermal shock behavior of ZrB₂--SiC ceramics was studied with water, air and methyl silicone oil as quenching media, respectively. The temperature of all coolants was room temperature (25°C) and the residual strength of the ceramics after quenching was tested. The strength of the ceramics after water quenching had an obvious drop when the temperature difference, ΔT, was about 275°C, while the residual strength of the specimens quenched by air and silicone oil only varied a little and even increased slightly when the temperature difference was higher than 800°C. The different thermal conductive coefficient of the coolants and surface heat transfer coefficient resulted in the differences in the thermal shock behavior. The formation of oxidation layer was beneficial for improving the residual strength of the ceramics after quenching.

Keywords

ultra-high temperature ceramic (UHTC) / zirconium diboride (ZrB₂) / silicon carbide (SiC) / thermal shock resistance / mechanical property