ABSTRACT
Residual stresses in ceramics are often greater in magnitude than those found in metallic materials. Thermal microstresses in excess of 2 GPa have been measured in some of the materials reported in this chapter. There are three important reasons for this. First, the relaxation of residual stresses by plastic deformation is difficult owing to the high yield stress of most ceramics. Second, the high stiffness typical of ceramics means that a large stress results from a given strain, imposed for instance by a thermal expansion mismatch or phase transformation. Finally, in the case of thermal residual stresses, the refractory nature of many ceramics allows, and in the case of sintering and other methods of densification, demands, very large thermal excursions which lead to correspondingly large thermal expansion mismatches.
