9. Creep and Recovery

The rate of decrease in deformation after load removal, following a long application during a creep experiment is discussed in this chapter. Constant temperature must be maintained in such experiments in order to eliminate the contributions of thermal expansion (contraction). Monolithic ceramics typically do not possess the elevated-temperature toughness required for safety-critical designs. For this reason, a considerable amount of effort has been devoted to the development of ceramics reinforced with continuous fibers. Most of the ceramics for various applications are usually in composite forms (and contain various additives in specified amounts), depending on their use for a definite purpose. A knowledge of creep-strain recovery behavior may be used to increase the lifetimes of components subjected to sustained- and cyclic-creep load.