【摘要】 研究了γ辐照聚碳硅烷(polycarbosilane,PCS)先驱丝在Ar与NH3中的热解过程,探讨了气氛与温度对化学结构演变、元素组成、晶型结构和微观形貌的影响。结果表明,热解温度低于600℃时,气氛对化学结构无影响;热解温度达700℃时,Ar中先驱丝的化学结构主要由Si—O—Si和Si—CH2—Si构成,而在NH3中发生了N与C的亲核取代反应,化学结构主要由Si—O—Si、Si—NH—Si和Si—NH2构成;1 000℃时,Ar中得到β-SiC晶型的SiC陶瓷纤维,NH3中得到无定型Si3N4陶瓷纤维。更多还原

【Abstract】 The pyrolysis process ofγ-ray irradiation curing of polycarbosilane precursor fibers in argon and ammonia atmosphere were studied.The effect of atmosphere and temperature on chemical structure evolution,elemental composition,crystal structure and microstructure were discussed.Results showed that the chemical structures of the fibers treated in two kinds of atmosphere had no difference below 600℃.At the temperature of 700℃,the chemical structures of the fibers treated in argon were composed of Si—O—Si and Si—CH2—Si, while the fibers treated in ammonia composed of Si—O—Si,Si—NH—Si and Si—NH2.When the temperature reached 1 000℃,SiC ceramic fibers withβ-SiC micro crystal were obtained in argon and amorphous Si3N4ceramic fibers in ammonia.更多还原