METHOD FOR PREVENTING LOW-TEMPERATURE DEGRADATION OF TETRAGONAL ZIRCONIA CONTAINING MATERIALS

摘要

A ceramic body having a surface region containing tetragonal zirconia is sintered to at least 95% theoretical density at a temperature below about 1550 DEG C. The surface region is then heat treated to reverse local stresses therein. Low temperature degradation in tetragonal zirconia, and materials containing tetragonal zirconia, is significantly inhibited. The heat treated ceramic is especially suited for use in structural components such as valves, engine housings, pistons (chambers) and the like which, during operation, are frequently exposed to temperatures ranging from room temperature to 500 DEG C. for prolonged periods of time.