Preparation of Zr-Si-C coating by chemical vapor reaction method

In order to improve the adhesion strength of Zr-Si-C coating, Zr-Si-C coating was prepared on SiC ceramic using a new chemical vapor reaction method, and based on a powder immersion reaction assisted coating process. The SiC ceramic was buried in Zr-1% (in mass) I₂ blended powders, and reacted with the blended powders at 850-1100°C. Iodine could accelerate the transfer of Zr atoms onto the SiC substrate, and the reactions between Zr and SiC led to the formation of a uniform Zr-Si-C coating on the surface of the SiC ceramic substrate. By using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy analysis combined with phase diagram analysis, the microstructure and phase composition of the coating were investigated. The Zr-Si-C coating is composed of a ZrC inner layer, a Zr₂Si-ZrC_1-x middle layer and a ZrC_1-x outer layer. By measuring the coating thickness, the growth kinetics of the coating was studied. Between 850 and 1100°C, the growth of Zr-Si-C coating followed the parabolic principle with activation energy of (210 ± 20) kJ/mol.