The impact of water and oxygen contents on the corrosion performance of yttrium silicate modified SiC_f/SiC composites under high temperature conditions

SiC_f/SiC composites have emerged as a prominent research area in the field of structural materials for engine hot-end applications. However, SiC_f/SiC composites exhibit susceptibility to oxidation and corrosion when exposed to oxygen and water vapor. The yttrium silicate ceramic in the SiC_f/SiC composite (SiC_f/SiC-YS composite) serves as corrosion-resistant matrix. The corrosion behavior of SiC_f/SiC-YS composites was assessed by examining the phase composition, microstructure, and bending strength after exposure to different water and oxygen environments. The results show that SiC_f/SiC-YS composites exhibit excellent resistance to water and oxygen at temperatures below 1300 °C. Above 1300 °C, the decomposition of yttrium disilicate affects the internal structure and bending strength of the composites. Temperature- and water vapor concentration-dependent crystal transformation of yttrium silicate is a crucial factor that influences the microstructure and water-oxygen corrosion resistance of SiC_f/SiC-YS composites.