摘要
将γ辐照聚碳硅烷先驱丝法制备的含氧氮化硅陶瓷纤维在惰性气氛中进行高温处理,利用抗拉强度测试、体积密度测试、XRD、SEM、TG-DSC和元素分析等手段研究了氮化硅陶瓷纤维在惰性气氛中的热稳定性,探讨了陶瓷纤维性能退化机理。结果表明,含氧氮化硅陶瓷纤维在惰性气氛中可经受1200℃高温,其微观形貌致密完整,抗拉强度保留率在93%左右;温度超过1200℃时,陶瓷纤维中SiNxOy相的分解使得陶瓷纤维表面出现大量微观缺陷并使得力学性能降低,在1400℃时氮化硅陶瓷纤维完全失去力学性能,晶形结构从无定型结构转变为α-Si3N4结构;高温下SiNxOy相分解产生的SiO2在陶瓷纤维表面呈现液相聚集状态并使得陶瓷纤维间熔并粘连,而分解产生SiO和N2的气体一方面导致了陶瓷纤维的失重,另一方面使得O含量降低而N含量升高。
Oxygen containing silicon nitride（ Si3N4） ceramic fibers prepared by pyrolysis of γ-ray irradiation curing polycarbosilane（ PCS） precursor fibers were heat treated in inert atmosphere. Thermal stability of the Si3N4 ceramic fibers in inert atmosphere was characterized by tensile strength testing,volume density testing,XRD,SEM,TG-DSC and elemental analysis. The degradation mechanisms of the ceramic fibers were discussed. The results showed that the oxygen containing silicon nitride ceramic fibers retained 93% strength when treated at 1200 ℃ and showed a compact microstructure. The tensile strength decreased sharply when the heat treated temperature exceeded 1200 ℃ because of micro defect derived from the decomposition of Si NxOyphase. At the temperature of 1400 ℃,the silicon nitride ceramic fibers lost their mechanical properties completely and transformed from amorphous state into α-Si3N4 crystalline. The SiO2 generated from the decomposition of Si NxOyphase at high temperature were gathered as liquid shape and made the ceramic fibers melt together. The SiO and N2 generated from the decomposition of SiNxOyphase firstly caused the weight loss,and made the oxygen content decrease and nitrogen increase.
出处
《硅酸盐通报》
CAS
CSCD
北大核心
2015年第7期1798-1802,共5页
Bulletin of the Chinese Ceramic Society
基金
国家自然科学基金项目(51462004)
关键词
氮化硅陶瓷纤维
聚碳硅烷
惰性气氛
热稳定性
silicon nitride ceramic fiber
polycarbosilane
inert atmosphere
thermal stability
