Effect of residual silicon on the oxidation resistance of bilayer Yb2Si2O7/SiC coated C/SiC composites at high temperature

The influence of residual silicon in C/SiC composites on oxidation resistance of bilayer Yb2Si2O7/SiC coating in ambient air were investigated. Results indicated that new micro-crack caused by overflow of residual silicon from matrix in C/SiC composites is detrimental to the oxidation resistance of Yb2Si2O7/SiC coating at 1773 K. However, oxidation resistance of the bilayer coating at 1673 K can be improved because the SiO2 film induced by oxidation of residual silicon can self-heal micro-cracks in C/SiC composites. After removing residual silicon in C/SiC composites, the bilayer Yb2Si2O7/SiC coating has good oxidation resistance for C/SiC composites matrix at 1673 K and 1773 K.