聚碳硅烷纤维在1-己炔气氛中不熔化处理制备低氧含量SiC纤维  

SiC fiber with a low oxygen content prepared by polycarbosilane fiber cured in 1-hexyne vapor

作　　者：毛仙鹤[1] 宋永才[1] 

机构地区：[1]国防科技大学新型陶瓷纤维及复合材料国防科技重点实验室,长沙410073

出　　处：《复合材料学报》2007年第6期68-76,共9页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金重点项目(50532010);国防科技重点实验室基金

摘　　要：将聚碳硅烷（PCS）纤维在1-己炔气氛中进行化学气相交联不熔化处理，与空气不熔化相比，能大大降低纤维的氧含量。PCS纤维在1-己炔气氛中反应，其组成和结构都发生了变化。结果表明，在卜己炔气氛中，PCS分子的Si—H键的反应程度和纤维的凝胶含量随温度的升高而逐渐增加。反应机制为1-己炔受热引发PCS分子中的Si—H和Si—CH。键断裂生成Si自由基和Si—CH。自由基，促进PCS分子间形成Si—CH2-Si交联结构，最终实现不熔化。反应中有少量己基引入到PCS分子结构中。制得的SiC纤维拉伸强度达到2．79GPa，氧含量降低到5wt％～6wt％，并且纤维的耐高温性能明显优于Nicalon纤维。在Ar气中处理至1300℃，纤维强度保留率约为80％，处理至1400℃，纤维的强度保留率为60％，并且在1300～1600℃的处理过程中，纤维中B—SiC微晶的晶粒尺寸变化只有2．18nm。Polycarbosilane （PCS） fibers cured in 1-hexyne vapor have much less oxygen than those cured by air. The composition and structure of PCS fibers transform during 1-hexyne curing process. The results show that the reaction degree of Si-H bond and gel content of PCS fibers rapidly increase when the curing temperature increases. Si--H and Si-CH3 bonds in PCS are induced by 1-hexyne to cleavage and form Si-central radicals. Fully developed crosslinking fibers come into being through the combination of these radicals. And a small amount of hexyl is introduced to PCS structure during the reaction. The tensile strength of SiC fibers prepared is 2.79 GPa and the oxygen content is 5wt%～6wt%. The fibers show better high temperature resistance than Nicalon fibers. After being exposed in Ar to 1300℃, the SiC fibers maintain 80% of the initial strength; after being exposed in Ar to 1400℃, they maintain 60% of the initial strength. And during the heat treatment from 1300 ℃ to 1600 ℃, the change of β-SiC＇s grain size is only 2.18 nm.

关 键 词：聚碳硅烷 1-己炔 化学气相交联 碳化硅纤维 

分 类 号：TQ343[化学工程—化纤工业]