SiC whisker-reinforced Si3N4-based composites without additives were compacted by underwater-shock wave. The composites contained 10, 20 and 30 vol%SiC whisker as reinforcements. There were no macrocracks in all shock compacted composites. The as-compacted and specimens sintered at various temperatures for 5 h were characterized by the measurements of relative density, micro Vickers hardness and fracture toughness. The relative density of sintered Si3N4-10 vol%SiC whisker composite was higher than that of sintered Si3N4-20 and 30 vol%SiC whisker composites, and reached the theoretical density by sintering at 1973 K. Hardness of each composite increased up to 1823 K in proportion to sintering temperature, and then saturated above 1823 K. The hardness and fracture toughness of the Si3N4-30 vol%SiC whisker composite sintered at 1973 K were about 29 GPa and 5.0 MPa√m, respectively. The fracture toughness was 25% higher than those of monolithic Si3N4 and other obtained composites sintered at the same temperature. SEM observation showed that whisker bridging and deflection were observed in sintered composites and that the matrix of the Si3N4-30 vol%SiC whisker composite consists of plate-like and submicron order fine needle-like β-Si3N4 grains.
|Number of pages||7|
|Journal||Journal of the Ceramic Society of Japan. International ed.|
|Publication status||Published - Apr 1 1993|
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