C/SiC材料主被动氧化烧蚀机理及计算方法研究

基于热化学平衡方法建立了任意比例C/SiC材料的主被动氧化烧蚀模型，开展了C/SiC材料氧化烧蚀机理的计算研究，并基于典型材料烧蚀试验结果进行了充分验证。计算结果表明，C/SiC材料的氧化烧蚀特性取决于表面温度、氧分压以及组分等因素，可能会出现主动氧化和被动氧化两种破坏机制，目前的烧蚀模型能够预测出任意比例C/SiC材料两种氧化烧蚀机制的转换过程；SiC含量对C/SiC材料的氧化烧蚀特性有明显的影响，随着SiC含量的提升，主/被动氧化转换临界分压会减小，材料的抗氧化性能越好；但当材料均处于主动氧化阶段时，SiC含量越高材料的无量纲烧蚀速率越大，材料的抗烧蚀性能减弱。

Investigation on Thermochemical Ablation Model for Active/Passive Oxidation Transition Mechanism of C/SiC Composite

The thermochemical ablation model for the C/SiC composite is established. The active/passive ablation performance of the C/SiC composite is studied numerically. The computational results conform well with the experimental results in the published literatures. The results indicate that the oxidation and ablation characteristics of the C/SiC materials depend on the surface temperature, oxygen partial pressure and material components. Two possible failure mechanisms, active oxidation and passive oxidation, may occur. The oxidation transition process could be predicted by the current model. The mass fraction of SiC would affect the ablation performance of C/SiC composite obviously. The composite is prone to cause the passive oxidation with the increase of the SiC mass fraction.