Effect of Y₂O₃ on the oxidation resistant of ZrSiO₄/SiC coating prepared by supersonic plasma spraying technique for carbon/carbon composites

An Y₂O₃ modified SiC/ZrSiO₄ multilayer coating for carbon/carbon (C/C) composites against oxidation at high temperature was prepared by supersonic plasma spraying technique and pack cementation. The microstructure and phase compositions of the coatings were characterized by SEM, EDS and XRD. Oxidation test results show that the coating could protect C/C composites from oxidation at 1823K in air for 210h and withstand 25 thermal cycles between room temperature and 1823K. The excellent protective ability is attributed to the fact that Y₂O₃ in coating can restrain the phase transformation of the ZrO₂ and improve the stability of the SiO₂ glass by formation of Y₂Si₂O₇ phase during oxidation.