High temperature oxidation resistance of Y2O3 modified ZrB2-SiC coating for carbon/carbon composites

Abstract To protect carbon/carbon (C/C) composites from oxidation at high temperature, Y2O3 modified ZrB2-SiC coating was fabricated on C/C composites by atmospheric plasma spraying. The microstructure and chemical composition of the coatings were characterized by SEM, EDS, and XRD. Experiment results showed that the coating with 10 wt.% Y2O3 presented a relatively compact surface without evident holes and cracks. No peeling off occurred on the interface between the coating and substrate. The ZSY10 coating underwent oxidation at 1450 °C for 10h with a mass loss of 5.77%, while that of ZS coating was as high as 16.79%. The existence of Y2O3 played an important role in inhibiting the phase transition of ZrO2, thus avoiding the cracks caused by the volume expansion of the coating. Meanwhile, Y2SiO5 and ZrSiO4 had a similar coefficient of thermal expansion (CTE), which could relieve the thermal stress inside the coating. The ceramic phases Y2SiO5, Y2Si2O7 and ZrSiO4 with high thermal stability and low oxygen permeability reduced the volatilization of SiO2.