Thermal stress resistance of engineering ceramics

Abstract

An overview is presented of the current understanding of the variables which affect the thermal stress failure of brittle structural ceramics for a variety of failure phenomena including thermoelastic instability, thermal fatigue and instantaneous thermal stress fracture, as well as stable and dynamic crack propagation. Analytical expressions for the thermal stress resistance for instantaneous fracture are given for a range of thermal conditions, including externally constrained thermal expansions under isothermal conditions, steady state heat flow, linear rate of heating and convective, conductive as well as radiative heat transfer. Data from the literature are cited, whenever available. For all thermal environments and failure modes, appropriate thermal stress resistance parameters (figures of merit) are presented, which allow the selection of the candidate structural ceramic with optimum thermal stress resistance for a specific thermal environment and failure mode. Recommendations are made for the development of ceramic materials with improved thermal stress resistance as well as the directions to be taken in engineering design in order to reduce the susceptibility of ceramic components or structures to thermal stress failure.