Silicon nitride-based ceramic composites

Initial results on the development of new SiC whisker/Si3N4 matrix composite ceramics are encouraging with significant improvements achieved in strength and fracture toughness. However, these have been achieved only on fully dense hot-pressed materials. A production route for economic fabrication of these ceramics composites requires the selection of a composition which enables a liquid-phase densification process by pressureless sintering to take place without interaction with the SiC whiskers, but which gives a final phase and microstructure beneficial to its subsequent use at elevated temperatures. (A)