WEI Zihan ¹, PENG Yuqing ¹, XU Haiming ¹, KANG Zhiwei ¹, WANG Mengqian ¹, LI Aijun ¹, LI Zhaoqian ²

(1. School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China; 2. Shanghai Aerospace Equipment Manufacturer Co., Ltd. Shanghai 200245, China)

Abstract:  3D SiC_f/SiBCN ceramic matrix composites were prepared through precursor infiltration and pyrolysis (PIP), whose oxidation behaviors in water-oxygen coupling environment (800-1200 ℃) were studied. SEM and XRD were used to characterize microstructure and phase composition of the composites before and after oxidation, while EDS was used to analyze the main elements on the surface of the composites after oxidation. It was found that the bending strength of the composites was largely degraded with a retention of only 33.56%, after wet oxygen oxidation at 800 ℃. However, the bending strength retention rates after oxidation at 1000 ℃ and 1200 ℃ were higher than 50%. This is attributed to the formation of a viscous SiO₂ oxide layer as the composites was oxidized at 1000 ℃ and 1200 ℃ for 50 h, which protected the fibers in the composites. Surface oxygen scanning results indicated that the self-healing oxide layer in the composites was mainly formed due to the oxidation of the SiBCN matrix during the oxidation process.

Key words:  SiC_f/SiBCN composite; wet oxidation; self-healing; matrix oxide