Effect of Coated Whiskers on the Mechanical Properties of SiC Whisker Reinforced Silicon Nitride Ceramic Composite

초록

Alumina or carbon coated SiC whiskers were prepared by homogeneus precipitation of alummun sulfate or the pyrolysis of phenlic resin. The Si3N4 composites reinforced with coated SiC whiskers were fabricated by hot-pressing at 1800 degree for 2h under an N2 atmosphere of 0.1MPa to examine the effects of coated whiskers on the mechanical properties of SiC whisker reinforced Si3N4 composite. By the addition of carbon cated SiC whiskers instead of alumina coated ones, the fracture toughness of composite was increased up to 7.7MPam1/2 which was 10% and 35% higher than as-received SiC whisker reinforced composite and Si3N4 monolithm respectively. This result seems to be caused by the fact that the crack deflection and whsiker pull-out were increased. Thus, carbon coated SiC whiskers were considered to form relatively weak interface bond with Si3N4 matrix.