Effects of La₂O₃ modification on the microstructure, mechanical and ablation properties of C/C-SiC composites were investigated. Experimental results show that a new La₁₀(SiO₄)₆O₃ phase was generated during heat treatment process. The presence of the La-compounds, namely La₂O₃ and La₁₀(SiO₄)₆O₃, had an important impact on the structure of reinforced skeleton and the molten oxide film, and thus strongly affected the mechanical and ablation properties of the composites. Excessive La addition induced the structural damage of the reinforced skeleton, resulting in weakened mechanical and ablation properties. The C/C-SiC composites with 25.65 wt.% La₂O₃ addition displayed better mechanical properties and the best ablation resistance. The La₁₀(SiO₄)₆O₃ phase could react with molten silica to form a viscous glass during ablation. The transformation of La-compounds into La₂Si₂O₇ can reduce the ablation of SiO₂ and enhance the glass film, so as to protect the composites from further ablation.

研究了La ₂ O ₃改性对C / C-SiC复合材料的微观结构，力学性能和烧蚀性能的影响。实验结果表明，在热处理过程中产生了新的La ₁₀（SiO ₄）₆ O ₃相。La化合物La ₂ O ₃和La ₁₀（SiO ₄）₆ O _3的存在，对增强骨架和熔融氧化膜的结构有重要影响，因此强烈影响了复合材料的机械性能和烧蚀性能。La过量添加会导致增强骨架的结构损坏，从而导致机械性能和烧蚀性能减弱。添加了25.65 wt。％La ₂ O ₃的C / C-SiC复合材料表现出更好的机械性能和最佳的抗烧蚀性。La ₁₀（SiO ₄）₆ O ₃相可在烧蚀过程中与熔融二氧化硅反应形成粘稠的玻璃。La化合物向La ₂ Si ₂ O ₇的转化可以减少SiO ₂的烧蚀并增强玻璃膜，从而保护复合材料免于进一步烧蚀。