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以聚碳硅烷(PCS)为先驱体,采用先驱体转化技术制备出耐高温的连续Si C纤维。研究了烧成过程中温度对纤维结构及性能的影响。结果表明,当纤维的烧成温度低于1 400℃时,纤维的拉伸强度随着温度升高缓慢上升;烧成温度为1 400℃时,氧的质量分数为1.96%,硅碳原子个数比为0.757 6,拉伸强度为2.7 GPa,晶粒尺寸为5.4 nm,惰性气氛下1 800℃处理1 h后,强度保留率为49.63%,空气气氛中1 250℃处理后,拉伸强度仍保留2.24 GPa。烧成温度在1 400℃之后,拉伸强度明显下降。当烧成温度为1 800℃时,拉伸强度为1.32 GPa。这主要是纤维中Si CxOy相分解和晶粒长大两方面的综合因素起作用。烧成温度较高的纤维,惰性气氛中的耐高温性能较好。这是因为其氧含量较低,且纤维的晶粒尺寸增加幅度较小。烧成温度为1 800℃的纤维惰性气氛下1 800℃处理1 h后,强度保留率为72.73%。
Using polycarbosilane (PCS) as the precursor, the continuous Si C fiber with high temperature resistance was prepared by the precursor conversion technology. The effect of temperature on the structure and properties of the fibers during sintering was investigated. The results show that the tensile strength of fiber increases slowly with increasing temperature when the firing temperature of fiber is less than 1400 ℃, the mass fraction of oxygen is 1.96% when the sintering temperature is 1400 ℃, The tensile strength was 2.7 GPa, the grain size was 5.4 nm, and the strength retention rate was 49.63% after 1 800 h treatment at 1 800 ℃ in inert atmosphere. After being treated at 1 250 ℃ in air, the tensile strength Remaining 2.24 GPa. After firing at 1400 ℃, the tensile strength decreased significantly. When the firing temperature is 1800 ℃, the tensile strength is 1.32 GPa. This is mainly due to the combination of Si CxOy phase decomposition and grain growth in the fiber. Fired higher temperature fibers, high temperature performance in an inert atmosphere is better. This is due to the lower oxygen content and the smaller increase in the grain size of the fibers. The strength retention was 72.73% after 1 h treatment at 1 800 ℃ in a fiber inert atmosphere with a firing temperature of 1 800 ℃.