Uniform incorporation of Y into SiC_f/SiC via a gel-assisted RMI process for enhanced water-oxygen corrosion resistance

SiC_f/SiC composites are attractive for hot-section components in next-generation aircraft engines but suffer rapid degradation in water-oxygen environments. To address this, we propose a matrix modification strategy that introduces yttrium via a gel-assisted precursor infiltration and pyrolysis, combined with reactive melt infiltration. This approach enables precise control of yttrium incorporation and distribution within the matrix, effectively avoiding residual stresses induced by the introduction of water-vapor-resistant elements that could otherwise compromise the mechanical properties and density of the composites. The water-oxygen corrosion behavior of the resulting Y-modified SiC_f/SiC composites was investigated at 1350 °C. Yttrium near the surface reacts with H₂O and O₂ to form dendritic Y₂Si₂O₇, which reinforces the surface oxide layer and mitigates vapor-induced damage. The internal microstructure remains stable, and the composites retain 96.66% of their flexural strength after 50 h of exposure. These results demonstrate that gel-enabled rare-earth modification effectively enhances corrosion resistance, offering a promising pathway for extending the durability of SiC_f/SiC composites in harsh aero-engine environments.