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Mechanical properties and microstructure evolution of KD-SA SiCf/BN/SiC CMCs oxidized at different temperatures |
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| Authors: | Liuwei Li Hao Qin Chunjing Liao Xiao You Han Luo Yudong Xue Xuezheng Yue Jinshan Yang Xiangyu Zhang Shaoming Dong |
| Affiliation: | 1. School of Materials Science and Engineering, University of Shanghai for Science and Technology, Shanghai, China;2. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China;3. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China;4. State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China Structural Ceramics and Composites Engineering Research Center, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, China Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China |
| Abstract: | Silicon carbide fiber-reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) based on a domestic KD-SA SiC fiber were exposed to a wet oxygen atmosphere for 135 h at 800, 1100, and 1300°C. The evolution of the microstructure and mechanical properties of SiCf/SiC CMCs have been systematically investigated following oxidation. For weight change, CMC-1300 showed the greatest gain (0.394%), followed by CMC-1100 (0.356%) and CMC-800 (0.149%). The volatilization of boron oxide (B2O3) combined with the slight oxidation of the SiC matrix at 800°C caused crack deflection and fiber pull-out. The complete dissipation of the interphase could be found when the oxidation temperature increases to 1100°C, generated a fracture surface with brittle fracture characteristics. At 1300°C, crystalline SiO2 hindered oxygen diffusion, with evidence of fiber pull-out. Based on thermodynamic calculations and microscopic observations, we propose a mechanism to explain the thermal degradation of SiCf/SiC CMCs. This work offers valuable guidance for the fabrication of SiCf/SiC CMCs that are suitable for high-temperature applications. |
| Keywords: | mechanical properties oxidation behavior oxidation mechanism SiCf/SiC CMCs |