SLURRY PROCESSING FOR FABRICATION OF SIC WHISKER-REINFORCED SI3N4 COMPOSITES

In order to solve the major problems of processing whisker-reinforced ceramic composites, such as agglomeration of whiskers, correlation bet ween pH and viscosity has been carefully investigated in a mixed slurr y of whiskers and matrix powder. SiC whiskers and Si3N4 powder were di spersed homogeneously by controlling pH in aqueous suspension, and the state was successfully fixed by a sudden change of pH to make the slu rry more viscous. The slurry was then filtrated rapidly and dried. The strength of hot pressed composites obtained by this procedure was sca rcely lowered, with increased whisker loading in the range 0-30 wt % a nd fracture toughness increased more than 75%.