Enhanced wet-oxidation resistance of Y2O3 modified SiC ceramics by the formation of Y2Si2O7 protective layer

The poor wet-oxidation resistance limits the long-life service of SiCf/SiC composites as the hot end components of aero-engines. The stability of SiCf/SiC composites under high-temperature wet oxygen environment can be promoted by more robust SiC matrix. In this work, the effect of Y2O3 on the corrosion behaviors of SiC ceramics in flowing O2/H2O atmosphere at 1400 degrees C was studied. Duo to the continuous Y2Si2O7 layer formed on the surface, SiC-Y2O3 ceramics exhibit much better wet-oxidation resistance than original SiC ceramics. During the oxidation process, Y2O3 dispersed in the ceramics migrates to the surface and reacts with SiO2 to form beta-Y2Si2O7. Subsequently, the beta-Y2Si2O7 aggregates and grows to form a continuous Y2Si2O7layer, inhibiting the corrosion from oxidizing medium to the inner SiC matrix. This study is expected to provide important ideas for the design and structure regulation of wet-oxidation resistant SiCf/SiC composites.