Ceramics as Structural Materials

A strong impetus for development of ceramic structures arises from the growing need for structural materials that may be used at high temperatures, particularly in aerospace structures. Ceramics are capable of supporting considerably larger loads in compression than in tension; some possess unusually high compressive strengths and relatively low density, characteristics enhancing their promise for lightweight structures. The fracture strengths of brittle ceramics usually show wide range of scatter, and appear to be related to the probability of the existence of flaws. Therefore, the designer of a ceramic structure must consider the nominal range characteristic of fracture strength values. The effects of size, shape, and method of fabrication of structural elements are important in this connection. The presence of randomly-distributed pores (of uncontrolled shape) in a ceramic drastically reduces its compressive strength; it has been found that directional cellulation has considerably less effect. Considerable promise exists in the use of prestressing with ceramics. A brief review is given of research with prestressed ceramics.