Fabrication of Gradient SiNO/SiC Fibers by Nitridation Pyrolysis

陶瓷纤维具有质轻、高强高模、耐高温、抗氧化、耐腐蚀等优异的性质，是优异的树脂基、陶瓷基和金属基复合材料的增强体，在航空航天、军用以及民用上都有着广泛的应用前景。陶瓷纤维作为一种重要的战略物资，对陶瓷纤维的研究也一直是一个世界性的热点研究课题。在此背景下，本论文结合PCS先驱体转化发制备SiC纤维和氮化热解制备Si3N4纤维的技术路线，以聚碳硅烷(PCS)电子束交联丝为原料，在NH3气氛下，通过控制氮化温度来调控氮化深度，随后在N2气氛下高温热解制备出一系列新型的具有梯度变化结构的SiNO/SiC纤维，对该纤维的组成和结构进行了详细地研究，并且结合纤维的结构探讨了对性能的影响规律。 研究发现：...Ceramic fibers have wide range of application prospects in the military and civilian as superb reinforcement of resin matrix, ceramic matrix, and metal matrix composites duo to its excellent properties such as light weight, high strength and high modulus, high temperature resistance, oxidation resistance and corrosion resistance. Ceramic fibers as important strategic resource, the study of ceramic...学位：工学硕士院系专业：材料学院_工程硕士(材料工程)学号：2072014115011

掺铁碳化硅陶瓷的制备及其吸波性能

将羰基铁和液态聚碳硅烷(LPCS)反应生成的铁(Fe)溶胶与固态聚碳硅烷(PCS)混合,合成出不同Fe质量分数的PCS先驱体,然后经氧化交联和高温热解制备了不同Fe质量分数的磁性碳化硅陶瓷(Fe/SiC),系统地研究了Fe元素的引入对SiC陶瓷的组成、结构、磁性能和介电性能的影响规律。研究发现,当Fe质量分数小于8.94%时,在热解过程中,Fe元素可以显著促进SiCxOy的分解,生成β-SiC,且随着Fe质量分数的增加,β-SiC的结晶峰越来越强;但随着Fe质量分数继续增加,达11.78%时,则主要生成Fe3Si;Fe/Si C陶瓷均呈铁磁性,其饱和磁化强度随着Fe质量分数的增加而呈指数形式增加;当Fe质量分数为4.19%时Fe/SiC陶瓷在12.4 GHz具有最小的反射损耗,为-9.4 dB,同时低于-5 dB的带宽为2.4 GHz,Fe质量分数为8.94%时,低于-5 dB的带宽则为3.7 GHz,可用作良好的微波吸收材料。国家自然科学基金(51603175);;中央高校基本科研业务费(20720150082)资助项目~

Preparation of SiNO Ceramic by Pyrolysis Nitridation of Polycarbosilane

系统研究了热解和氧化条件对聚碳硅烷氮化热解法制备SInO陶瓷的影响.研究发现,氮化脱碳反应主要发生在800℃之前,且脱碳彻底,碳质量分数低于1%;在氮气气氛下继续烧成,最终生成陶瓷的氮质量分数可达35.65%.氮化前对聚碳硅烷进行氧化交联可提高陶瓷产率至61.84%,但是产物中氮质量分数显著降低到20%以下,产物为无定型态的SInO陶瓷.SiNO ceramic has very excellent comprehensive properties and is one of the best candidates for ceramic matrix composites.In this work,influences of pyrolysis and curing conditions on the SiNO ceramic prepared with pyrolysis nitridation are systematically studied.The results show that decarbonization is completed before 800 ℃ with carbon residue lower than 1%(by mass).After pyrolysis in N2,nitrogen content is as high as 35.65%(by mass).Oxidation curing before ammonolysis can improve ceramic yield.The ceramic yield is 61.84%(by mass)but the nitrogen content decreases significantly(below 20%)by mass,and the product is amorphous SiNO ceramic.Therefore,high-yield and low-carbon-content SiNO ceramic can be prepared with pyrolysis nitridation of polycarbosilane.国家自然科学基金(51002127