随着直拉法热场尺寸的不断增大，单晶硅生产过程中已经大批量采用C/C复合埚帮替代石墨埚帮。但是，由于埚帮处在高温富Si环境中，经过一定时间后碳纤维出现异化现象，致使埚帮失效，高频次的更换增加了企业的生产成本。研究中利用XRD对碳纤维埚帮异化不同阶段物相进行分析，通过SEM对异化后的埚帮形貌进行观察，发现处在高温富Si氛围中的碳纤维变成了碳化硅。通过对单晶硅炉内流场和温度场分析，揭示了碳化硅的形成过程和机理。结合碳纤维硅化过程和反应机理分析了埚帮异化的主要原因，为后续高寿命埚帮设计和延长其使用寿命提供增强策略。

With the increasing of the thermal field size of the straight-pull method, the C/C composite crucible-holder has been widely used to replace the graphite crucible-holder in the production of single crystal silicon. However, due to the high temperature and Si-riched environment, the crucible-holder made of carbon fibers are easy to disassimilated, the high frequency of replacement increases the production cost to the enterprise. In this paper, the phase at different stages of carbon fiber’s dissimilar coating were analyzed by XRD, and the morphology of the dissimilar coating was studied by SEM. It was found that carbon fiber turned into silicon carbide in the high temperature and Si-riched environment. By analyzing the flow field and temperature field of the monocrystalline silicon furnace, the formation process and mechanism of silicon carbide were revealed.The main reasons for the dissimilarity were analyzed. The results can provide theoretical support to prolong the service life of the crucible-holder.