Chapter 9.9 - Development of Superplastic Ceramics

Abstract

Ceramic materials can be deformed extensively in tension above approximately two-thirds of the absolute melting point, provided they have a fine ( 2 ). This property is of interest because the ability to achieve large strains makes superplastic forming an attractive option for the manufacture of complex-shaped components. Ceramics, for example, oxides, nitrides, and carbides, are hard, strong, and stiff materials. They are brittle and lack the ductility of metals at ambient temperatures. The application of superplasticity makes it possible to fabricate ceramic components just like superplastic metals. A wide variety of superperplastic ceramics have been developed by controlling the microstructures to sub-micrometer scales, for example, oxides (ZrO 2 , alumina, and their composites), nonoxides (silicon nitride, silicon carbide, SIC), bioceramics, and superconductors. The progress in microstructural control leads to the development of high-strain-rate superplasticity in ceramics. The superplasticity of ceramics has been applied to superplastic forging, sinter forging, and superplastic joining. The superplastic sinter forging of silicon nitride is an efficient method to produce a component with improved strength and fracture toughness.