Oxidation Resistance of Si₃N₄-32 Vo1% SiC Nanocomposite

Abstract

Hot-pressed Si₃N₄-32%SiC nanocomposite and monolithic Si₃N₄ for comparision were evaluated for oxidation resistance at 1000-1400°C in static air for 100 hr. The weight gain of Si₃N₄-SiC nanocomposite was similar to that of Si₃N₄, except 1000°C. At 1000 and 1200°C oxidation, the surface layer containing cristobalite was formed, and yttrium disilicate was observed after 1400°C oxidation. The nanocomposite did not indicate a degradation in strength and even the strength increase of 20% was observed after 1200°C oxidation, whereas the strength degradation of 20-30%, due to a pit formation, occured for Si₃N₄.