Bending properties and fracture mechanism of C/C composites with high density preform  

高密度预制体制备炭/炭复合材料的弯曲力学性能与断裂机制(英文)

作　　者：张明瑜[1] 苏哲安[1] 李建立[1] 黄启忠[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,长沙410083

出　　处：《Transactions of Nonferrous Metals Society of China》2011年第8期1795-1800,共6页中国有色金属学报（英文版）

基　　金：Project (50802115) supported by the National Natural Science Foundation of China;Project (2011CB605801) supported by the National Basic Research Program of China

摘　　要：C/C composites with banded structure pyrocarbon were fabricated by fast chemical vapor infiltration（CVI）,with C3H6 as carbon source,N2 as carrier gas,and three-dimensional（3D） 12K PAN-based carbon fabric with high density of 0.94 g/cm3 as preform.Experimental results indicated that the fracture characteristics of C/C composites were closely related to the frequency of high-temperature treatment（HTT） at the break of CVI process.According to the load？displacement curves,C/C composites showed a pseudoplastic fracture after twice of HTT.After three times of HTT,load？displacement curves tended to be stable with a decreasing bending strength at 177.5 MPa.Delamination failure and intrastratal fiber fracture were observed at the cross-section of C/C composites by scanning electronic microscope.Because the content of pyrocarbon and fibers has a different distribution in layers,the C/C composites show different fracture characteristics at various regions,which leads to good toughness and bending strength.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。

关 键 词：C/C composites chemical vapor infiltration（CVI） high density preform bending properties fracture mechanism 

分 类 号：TB332[一般工业技术—材料科学与工程]