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采用恒温热重法测定了在空气中 ,0 .1 MPa、673 K到 973 K下预氧丝 (即预氧化聚丙烯腈纤维 )原位炭化无粘结剂 C/ C复合材料的氧化失重率 ;并利用扫描电镜分析了这种复合材料氧化前后的结构 .氧化动力学测定结果表明 :该材料在氧化开始时 ,其氧化速率随时间的增长而增大 ,然后随时间的延长而减小 ,并趋向恒定 .研究表明 :该材料中预氧丝与基体炭界面结合处是空气中氧的扩散通道 ,杂质为空气中氧的吸附起到了提供吸附活性中心的催化作用 ,氧化反应的控制步骤为被吸附氧的离解 .
The oxidative weight loss of in-situ carbonized binder-free C / C composites pre-oxidized at 0 .1 MPa and 673 K-973 K (ie, pre-oxidized polyacrylonitrile fibers) in air was measured by thermogravimetry The structure of the composite before and after oxidation was analyzed by scanning electron microscopy.The results of oxidation kinetics showed that the oxidation rate of the composite increased with time and then decreased with time, And tends to be constant.The results show that: the preoxidized silk in the material at the interface with the matrix carbon is the diffusion channel of oxygen in the air, the impurity is the oxygen adsorption in the air has played a catalytic role in the adsorption activity center, the oxidation reaction control step Dissolved oxygen is dissociated.