An ascending thermal shock study of ceramics: Size effects and the characterization method

Abstract

The ascending thermal shock resistance of ceramics is studied using a new, simple and efficient test method. The results show that our testing succeeds in developing internal cracks in the shocked specimen that are cause by tensile stresses, while there is no visible change in the surface morphology. This coincides with the failure mechanism of ascending thermal shock, and this has not been reported before. Considering there is no proper experimental characterization parameter for evaluating the ascending thermal shock resistance, we propose an experimental evaluation index called the critical temperature difference of rupture, which is defined as the temperature difference after which a sharp decrease of retained strength appears until fracture. The value of the critical temperature difference of rupture is determined by the microstructures and material properties. A method for modelling the critical temperature difference of rupture of a rectangular specimen is proposed.