Stress Corrosion of Silicon Nitride

Abstract

The results of an investigation to determine stress corrosion effects on Si3N4 are presented. Variable‐strain‐rate and static‐fatigue tests were performed on hot‐pressed and reaction‐sintered materials. Both materials exhibited time‐dependent failure in an atmosphere of water‐saturated flowing air. The effect is moisture‐dependent, as indicated by a strength increase of = 10% for tests performed in dry air. A model is proposed for the mechanism of stress corrosion of hot‐pressed Si3N4 based on ion exchange occurring in the glassy grain‐boundary phase.