High‐Temperature Stress Corrosion Cracking in Ceramics

Abstract

Single‐phase ceramics are shown to be susceptible to stress corrosion cracking at elevated temperatures in the presence of a wetting amorphous deposit. Crack arrest occurs when the crack is depleted of amorphous material, provided that the stress intensity is below a “blunting” threshold. A preliminary model of such cracking has been developed. The model considers stress corrosion as a process wherein the corrosive medium, by virtue of its wetting characteristics, allows the crack to propagate along grain boundaries. A crack velocity that depends sensitively on the dihedral angle is predicted. Furthermore, since the corrosive medium acts as a conduit for rapid atom transport to the crack tip, the crack velocity also exhibits a strong dependence on the viscosity of the fluid medium. Implications for such stress corrosion processes on premature failure are discussed.