Y/YbB₄-modified SiC_f/SiC composites with enhanced water-oxygen corrosion resistance

Silicon carbide fibers-reinforced silicon carbide matrix (SiC_f/SiC) composites, which are commonly used as thermal structural materials in different components, e.g., combustion chamber liners, are susceptible to water-oxygen corrosion, resulting in rapid performance degradation and structural collapse. To enhance their resistance to water-oxygen corrosion, the incorporation of rare-earth silicates (RE silicates) has been explored. In this study, novel Y/YbB₄-modified SiC_f/SiC composites, with superior resistance to water-oxygen corrosion, are fabricated using a combination of slurry infiltration (SI) and reactive melt infiltration (RMI) process. Results demonstrate that Y/YbB₄-modified SiC_f/SiC composites exhibit open porosity of 3.2 ± 0.4%, corresponding to remarkable reduction of 69.8% compared to CVI-SiC_f/SiC composites. Furthermore, after being exposed to water-oxygen environment at 1200 °C for 100 h, the surface of Y/YbB₄-modified SiC_f/SiC composites displays various yttrium silicates and ytterbium silicates. The material exhibits strength retention of 76.84%, indicating a notable improvement of 15.71% over the CVI-SiC_f/SiC composites.