Temperature dependence of the fracture strength of porous ceramic materials

Abstract

In spite of the extensive use of porous ceramic materials in high-temperature applications, there are very few experimental and no theoretical studies on analyzing their temperature-dependent fracture behavior. In this work, in order to fill this research gap, a novel theoretical model for the characterization of fracture strength of porous ceramic materials with respect to temperature is proposed. The model considers the effects of the Young's modulus, specific heat capacity, volume fraction of pores, sizes of pore and flaw (critical flaw size). Further, through simplification the model can be used for the characterization of the strength of the dense ceramic materials. The models are verified by the obtained excellent agreements between the predictions and measurements. The experimentally observed phenomena are analyzed and explained according to the predicted results. Our analysis indicates that the temperature dependence of the fracture strength of the porous ceramic materials in vacuum is controlled by the Young's modulus and volume fraction of pores. While on high temperature oxidation the critical flaw size with respect to temperature should be considered. Furthermore, the temperature dependence of the strength of the dense ceramics is governed by the Young's modulus.