SIC PLATELET AND SIC PLATELET-ALUMINA REINFORCED TZP MATRIX COMPOSITES

SiC platelet-TZP and SiC platelet-Al2O3-TZP composites were fabricated from dispersions of SiC platelets in solutions containing salts of zi rconium, ytttrium, and aluminium. After coprecipitation and drying, th e resulting powders were hot pressed at 1550 degrees C using a pressur e of 25 MPa in an argon atmosphere. The resulting microstructure consi sted of a uniform distribution of SIC platelets in a TZP matrix. Addit ion of SiC platelets resulted in a loss of both strength and roughness at all temperatures compared with the monolithic material. Additions of Al2O3 to the SiC platelet-TZP composite was useful in enhancing the strength and toughness at room temperature, and also the elevated tem perature strength compared with equivalent alumina free materials. Pha se analysis measurements showed that additions of Al2O3 promoted incre asing amounts of tetragonal --> monoclinic zirconia transformation dur ing fracture.