Corrosion behavior and mechanical properties of SiC/SiC composite joints with Y₂O₃-Al₂O₃-SiO₂ interlayer under high-temperature steam environments at 1200 °C

The study investigated the corrosion behavior and mechanical performance of SiC/SiC composite joints with Y₂O₃-Al₂O₃-SiO₂ (YAS) interlayers under high-temperature steam environments at 1200 °C. Under low-flow conditions, partial disruption of Si-O and Al-O bonds in the YAS glass network reduced crosslinking, forming an aluminosilicate protective layer that inhibited further corrosion. Prolonged exposure led to Y³⁺ migration and accumulation, resulting in Y₂Si₂O₇ precipitation and growth. High-flow conditions caused a thinner glass layer, continuous longitudinal cracks, and more severe erosion and dissolution of the YAS glass due to higher steam velocity. Despite these degradations, the joints exhibited satisfactory performance, maintaining shear strengths of about 40 ± 2 MPa after 15 h of low-flow exposure and about 36 ± 5 MPa after 5 h of high-flow exposure. These findings demonstrate that YAS interlayers provide excellent corrosion resistance and mechanical stability as a sealant for nuclear-grade SiC/SiC.