MDOxidation behavior in wet oxygen environment of Al2O3 modified SiCf/(SiC + B4C) at 1200 °C

The influence of Al2O3 on the oxidation behavior of SiCf/(SiC + B4C) composite materials at 1200 °C in O2/H2O (40/60) atmosphere was studied employing Scanning Electron Microscope, X-ray Diffraction and Material Universal Testing Machine. Results showed that Al2O3 could impede the crystallization of oxide (cristobalite) during cooling, and lead to a dense and smooth oxidized layer. Furthermore, the strength retention rate increases from 70.44 to 85.94% with Al2O3 after oxidization for 200 h. The above results are attributed to high viscosity and low reaction activity with steam of the aluminosilicates melt. Therefore, Al2O3 can significantly improve the oxidation resistance of SiCf/(SiC + B4C) composites in O2/H2O atmosphere.