Method for preparing dense, pressureless sintered SiC whisker reinforced composite ceramics

摘要

Whisker reinforced composites having improved strength and toughness are prepared by a process including densification by essentially pressureless sintering. There is no need to hot press or hot isostatic press to achieve a density of 99+% of theoretical for 10 vol. % whiskers and 93+% for 20 vol. % whiskers. The composites are derived from the desired volume fraction of whiskers, a sintering aid preferably submicron in average size range, and a major portion of a pressureless sinterable matrix material having an average particle size of not more than about 0. 5 micron. Yttria-alumina composites are sintered at less than about 1800. degree. C. and for less than about two hours to avoid surface degradation.