Thermal Shock Resistance of Si_3N_4/hBN Ceramic Composites

摘要

Si_3N_4/hBN composites were fabricated by hot isostatic pressing at 1700°C/3h with 1, 3 and 5 wt. % micro-sized or nano-sized hexagonal boron nitride particles added to silicon nitride matrix. An indentation quench test method was used for estimation of thermal shock resistance of monolithic Si_3N_4 and Si_3N_4/hBN composites. Thermal shock resistance of the composites increased with the increase of size and volume of hBN particles. The critical temperature difference for the composites with micro-sized hBN was significantly higher (over 900°C) compared to the monolithic silicon nitride (580°C).