Effect of sintering temperature on microstructure and properties of SiC coatings for carbon materials

SiC coating for the graphite materials was prepared by slurry-sintering technique in a vacuum. The phase, microstructure, thickness and resistance against irradiation of the SiC coatings prepared from 1500 to 1800 °C were investigated. Research results showed that, the porous β-SiC coating occurred at 1500 and 1600 °C, while compact β-SiC/Si coatings obtained at 1700 and 1800 °C. The thickness of the coatings was in most cases around 150 μm when the sintering was performed at 1500 and 1600 °C. However, the thickness was decreased, and the crystal size of SiC particles was increased when the sintering temperature was higher than 1600 °C. Thermal fatigue tests showed that, based on the surface morphology changes, the sintering temperature of 1700 and 1800 °C gave much improved irradiation resistance over that of coatings formed at 1500 and 1600 °C.