THERMOCHEMICAL LIMITATIONS OF CERAMIC MATERIALS

Nonoxide and oxide ceramics and composites are classes of potentially useful high-temperature materials. The ultimate temperature capabiliti es of these materials have both thermomechanical and thermochemical li mitations. In this paper, the major thermochemical limitations are exp lored. For nonoxides such as SiC, Si3N4, and A1N, these limitations ar e oxidation and volatility (external reactions) and phase changes and interfacial reactions (internal reactions). For oxides such as Al2O3 a nd stabilized ZrO2, these limitations are volatility, phase changes, a nd interfacial reactions. Where possible, specific upper temperature l imits are set.