AN Yb2Si2O7 OXIDATION RESISTANCE COATING FOR C/C COMPOSITES BY SUPERSONIC PLASMA SPRAY

An efficient glass coating was prepared on the surface of SiC coated C/C composites by supersonic plasma spray to prevent them from oxidation at 1873 K. The structure of the as-obtained coating was characterized by X-ray diffraction, scanning electron microscopy and isothermal oxidation test at 1873 K in air, respectively. Results show that the achieved Yb2Si2O7 outer coating was dense and it was bonded well with the SiC inner layer such that the oxidation protective ability and the thermal shock resistance were improved. After oxidation in air at 1873 K for 328 h and thermal cycling between 1873 K and room temperature for 17 times, the mass gain rate of the coated sample was only 0.28 %. A dense layer about 5 mu m between the SiC inner coating and the Yb2Si2O7 outer coating was in favor of the enhancement of the oxidation resistance of the SiC/Yb2Si2O7 coating for C/C composites.