Oxidation-induced strengthening in ground silicon carbide

Abstract

The strength enhancement of non-oxide structural ceramics (carbides, borides etc) has always been a major challenge. To this end, the effect of pre-oxidation on strength of silicon carbide with ground surface, machined using diamond wheels with varying grit sizes of 127m, 64 m, 42 m, 32 m, was investigated. The experimental results showed that the room temperature strength of ground specimens was improved because both grinding-induced-cracks and pre-existing surface flaws were healed during oxidation in air. After heat-treating, the strength measurements indicated a constant value of about 470 MPa, independent of the surface condition. Moreover, the strength remained almost constant up to 14000C, when the ground specimen was heat-treated at 15000C for 50h in air.