Preparation and sintering of silica-coated silicon carbide composite powder

SiO2-coated SiC powders were prepared via rotary chemical vapor deposition and consolidated by spark plasma sintering. Thin amorphous SiO2 layers were deposited uniformly on SiC powders at 948 K at deposition time from 2.7 to 7.2 ks. The resultant SiO2-coated SiC powders were sintered, and the effects of the sintering temperature on the phase, morphology, relative density, and mechanical property were investigated. The SiO2-coated SiC sintered body fabricated at 1923 K was nearly fully densified, with a mosaic structure consisting of small SiC particles and a thin SiO2 matrix, and exhibited high hardness (HV = 17.1 GPa) and toughness (KIC = 8.4 MPa m1/2).