15 - Thermal shock of ceramic matrix composites

Abstract

This chapter presents an overview of the performance of Ceramic Matrix Composites (CMCs) under conditions of thermal shock, i.e. when they are subjected to sudden changes in temperature during either heating or cooling. Such conditions are possible in the high-temperature applications for which these materials are targeted. The description of the thermal shock behavior of CMCs is given with reference to the thermal shock resistance of monolithic ceramic materials. Monolithic ceramics have greater thermal shock sensitivity than metals and can even suffer catastrophic failure due to thermal shock because of an unfavorable ratio of stiffness and thermal expansion to strength and thermal diffusivity, and their limited plastic deformation. CMCs exhibit superior resistance to thermal shock, compared to their monolithic counterparts, as catastrophic failure can always be avoided. Resistance to higher temperature differentials and property retention after the onset of thermal shock cracking can be realized, provided that the mechanical and thermal properties of CMCs are optimized by careful choice of their constituents.