SiC/C纤维热力学生长机理研究

Thermodynamic Growth Mechanism of SiC/C Fibers

使用乙二醇作为稀释剂将硅溶胶稀释,得到不同浓度的硅溶胶溶液,用作涂覆商用碳纤维的原料。碳纤维表面改性后涂覆硅溶胶溶液,取出后在Ar气氛中于1600℃保温30 min,硅溶胶涂层与碳纤维发生碳热还原反应形成SiC覆盖层。对制得的产物进行形貌和结构表征,并根据热力学数据对SiC包覆层的生长动力学和高温扩散机制进行研究。计算结果表明,反应过程为扩散控制。SiC/C纤维比碳纤维有更优异的耐高温氧化性能,为低成本制备新型陶瓷纤维提供可借鉴的思路和热力学依据。

The silica sol was diluted with ethylene glycol as diluent to obtain different concentrations of silica sol solutions,which were used as raw materials for coating commercial carbon fibers.After surface modification,the carbon fibers were coated with silica sol solution and held at 1600℃ for 30 min in the Ar atmosphere.The silica sol coating and carbon fibers underwent carbothermal reduction reaction to form SiC coating.The morphology and structure of the products were characterized,and the growth kinetics and high temperature diffusion mechanism of SiC coating were studied according to thermodynamic data.The calculation results show that the reaction process is diffusion controlled.The SiC/C fibers have better oxidation resistance at high temperature than the carbon fibers,which provides a useful idea and thermodynamic basis for the low-cost preparation of new ceramic fibers.