Oxidation protection of carbon/carbon composites with a plasma-sprayed ZrB2–SiC–Si/Yb2SiO5/LaMgAl11O19 coating during thermal cycling

Carbon/carbon composites were plasma sprayed with a ZrB2–SiC-Si/Yb2SiO5/LaMgAl11O19 coating to improve the oxidation resistance at high temperature. Oxidation protection behavior of the coating was investigated by thermal cycling test using a gas flame about 2273 K. Results showed that the weight loss for the completely coated sample was only 0.30% after 10 cycles of heating for 79 min, and it gradually increased to 4.8% until the failure of coating with 24 cycles. The presence of through-cracks and horizontal cracks in the coating due to the durative oxidation of ZrB2–SiC–Si layer progressively accelerated the oxidation of substrate and failure of coating.