碳含量及其结构对 SiOC 陶瓷纤维抗氧化性的影响

摘要

以乙烯基三甲氧基硅烷(VTMS)、正硅酸乙酯(TEOS)和苯基三甲氧基硅烷(PTMS)为原料，采用溶胶-凝胶法制备出了致密的 SiOC 纤维.研究结果表明，通过在 VTMS 中加入不同比例的 TEOS 或者 PT-MS 可以把 SiOC 陶瓷纤维的碳含量在21．8％~30．1％之间调节.纤维中碳的含量和结构对其抗氧化性有显著影响.抗氧化性随着碳含量和碳畴尺寸的增加而下降，以75％ VTMS-25％ TEOS 为原料制备的SiOC 陶瓷纤维在空气中氧化时可以在纤维表面形成致密的氧化膜，降低氧扩散速度，使该纤维具有良好的抗氧化性.%Silicon oxycarbide fibers were prepared from vinyltrimethoxysilane (VTMS ), tetraethoxysilane (TEOS)and phenyltrimethoxysilane (PTMS)by sol-gel method.It was found that the carbon content of the silicon oxycarbide fibers can be adjusted from 21.8% to 30.1wt% by change the mole ratio of VTMS,TEOS and PTMS in the precursors.The oxidation resistance of the fibers was impacted by the content and structure of carbon.The oxidation resistance decreased with the increasing content and domain size of the carbon.Silicon oxycarbide fibers prepared with 75%VTMS-25% TEOS showed good oxidation resistance in air at 600 ℃,be-cause a thin and dense silica film was formed on the surface of the fibers,preventing fibers from further oxida-tion.