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以丙烯作为碳源,氮气作为载气,采用初始密度为0.94g/cm3三维正交PAN基12K炭纤维预制体,利用自制的快速CVI炉制备基体热解炭结构为带状结构的C/C复合材料。力学性能测试结果表明,材料的弯曲断裂特征与制备过程中受到的高温热处理次数有关。从载荷-位移曲线来看,当C/C复合材料经过两次热处理时,C/C复合材料呈明显假塑性断裂特征。当C/C复合材料经过三次热处理时,载荷-位移曲线趋于稳定平滑,抗弯强度降低。从C/C复合材料断面的SEM图可以观察到材料断裂可以分为层间断裂和层内断裂,而层内断裂又因热解炭填充密度变化呈明显的分区断裂。由于热解炭和纤维含量在C/C复合材料中分布的差异,材料在不同的区域表现出不同的断裂特征,从而使得材料具备良好的弯曲强度同时具有一定的韧性特征。
Using propane as carbon source and nitrogen as carrier gas, a three-dimensional orthogonal PAN-based 12K carbon fiber preform with an initial density of 0.94g / cm3 was used to prepare a C / C Composites. The mechanical properties test results show that the bending fracture characteristics of the material are related to the number of high temperature heat treatment during the preparation. From the load-displacement curve, C / C composites show obvious pseudoplastic fracture characteristics when the C / C composites undergo two heat treatments. When the C / C composites after three heat treatment, the load-displacement curve tends to be stable and smooth, bending strength decreased. From the SEM images of the C / C composites, it can be observed that the material fracture can be divided into interlaminar and interlaminar faults, while the interphase faults are obviously subdivided due to the change of packing density of pyrolytic carbon. Due to the difference in the distribution of pyrolytic carbon and fiber content in C / C composites, the material shows different fracture characteristics in different regions, which makes the material have good flexural strength and certain toughness characteristics.