Oxidation protective AlPO4 coating for SiC coated carbon/carbon composites for application at 1773 K and 1873 K

Cristobalite aluminum phosphate (Cristobalite–AlPO4) coating was deposited on SiC pre-coated C/C composites (SiC–C/C) by a pulse arc discharge deposition. The phase compositions, microstructures and oxidation resistance of the multilayer coatings were investigated. Results show that pulse arc discharge deposition is an effective route to prepare dense and homogeneous AlPO4 coating on SiC–C/C composites. The AlPO4/SiC multilayer coatings can effectively protect C/C composites from oxidation in air at 1773 K for 160 h with a weight loss of 0.70% and at 1873 K for 100 h with a weight loss of 1.8%, and the corresponding weight loss rates are 1.14 × 10−3 g cm−2 h−1 and 4.84 × 10−3 g cm−2 h−1, respectively.