石英纤维析晶行为

为了提高石英纤维/ SiO₂ 复合材料的强度, 避免因石英纤维析晶而造成复合材料力学性能的降低, 本文中详细地研究了石英纤维的析晶行为。采用FT-IR 技术测试了石英纤维的化学键结构, 应用DSC 和XRD 技术综合分析了石英纤维的析晶过程, 并结合SEM、TEM 观察了石英纤维的析晶现象及产物。测试结果表明, 石英纤维结构中含有大量的Si —OH 键; 析晶过程受结构重排控制较为明显, DSC 曲线中存在明显的结构重排吸热峰。XRD 测试显示, 石英纤维析晶产物为单一α-方石英相, 起始析晶温度为950 ℃, 1400 ℃左右达到析晶最大量, 温度明显低于石英玻璃的析晶温度。Si —OH 键、杂质以及界面等因素是石英纤维析晶温度低于石英玻璃的主要原因。 

Crystallization of quartz fiber

In order to improve the st rength of the quartz fiber/ SiO2 composite , and escape the reduction of themechanical property by crystallization of the quartz fiber , the crystallization is studied in detail. The chemical bondst ructure of the quartz fiber was examined by FT-IR , and the crystallization process of the quartz fiber was analyzedby DSC and XRD. The crystallization photograph and production were observed by SEM and TEM. The resultsindicate that there are some Si —OH bonds in the quartz fiber and the crystallization process is cont rolled by st ructure rearrangement which can be seen in the DSC curve. The crystallization start s at 950 ℃ and get s to the top at1400 ℃. The XRD result shows that the product is onlyα-cristobalite , and the beginning temperature is lower thanthat of the bulk quartz glass. The Si —OH bond , impurity and phase interface are the important factors for the crystallization temperature of the quartz fiber to be lower than that of the quartz glass.