将 PCS 电子束交联丝在氨气氛中氮化热解、脱碳氨化,继在氮气氛中高温热引发缩合/转氨基反应,生成硅氮烷并最终形成氮化硅(Si3 N4)纤维。所制备的 Si3 N4纤维白色透明,横截面和表面均光滑致密,无明显缺陷和孔洞。还研究了氮化热解的反应机理以及热解工艺对氮化硅(Si3 N4)纤维结构和性能的影响。红外光谱和元素分析的结果显示,氮化热解脱碳彻底,Si3 N4纤维 C 含量<1%；烧结温度提高,N含量随之增加,O 含量则先增后减；烧结温度不超过1500℃,纤维为无定型。力学性能结果分析表明,随热解温度的提高,纤维力学性能先提后降,1300℃时达到最大值。氮化热解过程是采用NH3进行脱碳氨化,并在N2气氛下高温热引发缩合/转氨基反应产生硅氮烷并最终形成Si3 N4的过程。
In this work,PCS cured fibers were pyrolysis nitridation in the ammonia atmosphere for carbon re-moval and amination,and then condensation/nitridation reaction at high temperature in the nitrogen to produce Si3 N4 fibers.Results showed that as-prepared Si3 N4 fibers were colorless and transparent.What was more,the skin of the fiber was smooth and the cross section was rather dense without identifiable defects.This paper also discussed the mechanism of nitridation and the influence of pyrolysis conditions on the structure and properties of Si3 N4 fibers.The results of FT-IR spectra and elemental analysis showed that the carbon content was ex-tremely low after amination and pyrolysis,which was less than 1%,while the nitrogen content increased with the elevated pyrolysis temperature,and the oxygen content first increased and then decreased with the elevated pyrolysis temperature.The fibers were amorphous when the pyrolysis temperature was less than 1500℃,while the tensile strength reached a maximum at 1300℃.The processes of pyrolysis nitridation were a process of de-carburization and ammonification,and then condensation/nitridation at high temperature in the nitrogen,finally producing Si3 N4 fibers.
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