C/C复合材料孔隙结构的研究进展  

Advances in Research on Pore Structure of C/C Composites

作　　者：樊凯 卢雪峰[1] 吕凯明[1] 钱坤[1] FAN Kai;LU Xuefeng;LYU Kaiming;QIAN Kun(Key Laboratory of Eco-Textiles Ministry of Education,Jiangnan university,Wuxi 214122)

机构地区：[1]江南大学生态纺织教育部重点实验室

出　　处：《材料导报》2019年第13期2184-2190,共7页Materials Reports

基　　金：江苏高校优势学科建设工程资助项目(PAPD);连云港市产业前瞻与共性关键技术科技项目(CG1520);江苏省产学研联合创新资金-前瞻性联合研究项目(BY2016022-07);“十三五”国家重点研发计划项目(2016YFC0304301;2016YFB0303200);中央高校基本科研业务费专项资金资助(JUSRP51718A)~~

摘　　要：孔隙作为C/C复合材料结构中的重要组成部分,直接影响复合材料的致密化过程及其力学、氧化、烧蚀等性能,并赋予C/C复合材料许多潜在功能。C/C复合材料的致密化过程是基体炭不断填充碳纤维预制体内部孔隙的过程。从C/C复合材料的制备原理及工艺方面来说,C/C复合材料通常需要在碳氢气体若干个连续热分解周期下或在树脂、沥青等液相前驱体多个浸渍炭化循环下获得。不同结构的碳纤维预制体内部纤维和纤维束的交织及取向排列各异,导致C/C复合材料内部孔隙大小及形状、孔隙分布、孔隙贯穿通道等各不相同,进一步导致液相或气相的前驱体浸渍预制体的难易程度、在预制体中的流动路径以及对孔隙的填充状况不尽相同。另外,每个致密化周期内,材料内部致密化程度、孔隙结构变化等均不相同。前驱体在预制体内的填充、炭化后的形态及分布等都会对下一个致密化周期中前驱体的扩散传输产生影响。因此,结构不同的预制体即使具有相同的初始密度,其制备的C/C复合材料也存在明显的性能差异。孔隙对C/C复合材料性能的影响主要表现为材料力学性能及高温环境下材料的氧化、烧蚀行为的变化。在力学性能方面,一方面孔隙的存在减小了材料载荷承受面积,为材料发生形变提供了空间;另一方面,材料内部较大的孔隙或者微孔聚集处在受到外部载荷时会产生应力集中现象。此外,界面间的裂纹会在载荷作用下随着纤维与基体脱粘呈曲折扩展。在高温氧化环境中,大量的纤维束间的孔洞、基体中孔隙以及纤维/基体间的微裂纹将成为氧化气氛的扩散通道,从而加快氧化气体在材料内部的扩散以及碳纤维的氧化,进而导致复合材料迅速氧化失效。因此,需要根据应用环境,合理控制材料的孔隙数量和孔隙结构。As an important part of C/C composites, pores directly affect the densification process and mechanical, oxidation, ablation performance of C/C composites, endow the C/C composite with many potential functions. The densification process of C/C composites is a process in which carbon matrix is continuously filled with pores in carbon fiber preform. According to the preparation principle and process of C/C composites, C/C composites usually require several successive thermal decomposition cycles of hydrocarbon gas, or multiple impregnated carbonization cycles of liquid phase precursors like resin and asphalt. The variations in interwoven and oriented arrangement of fibers or fiber bundles in the carbon fiber preforms with different structure bring about the diversity of pore size and ship, pore distribution and pore passage of C/C composites, which further lead to the dissimilarity in the impregnation for the precursor into the preform, the flow path in the preform, and the filling state of the pores. In addition, the degree of internal densification and change of pore structure vary in the each densification cycle. Moreover, the filling of precursor in the preform and the morphology and distribution of the precursor after carbonization will affect the diffusion and transport of the precursor in the next densification cycle. Therefore, even if the preforms with diverse structures show the same initial density, the C/C composites still exhibit obviously different performance. The effect of pores on the properties of C/C composites is mainly manifested by changes in mechanical properties, oxidation and ablation behavior in high temperature environments. In terms of mechanical properties, on the one hand, the pores reduce the load-bearing area and provide space for the deformation of the material. On the other hand, stress concentration will be generated at gathering location of large pores or micropores in the material when they are subjected to external loading. In addition, the interfacial crack will exhibit a tortu

关 键 词：C/C复合材料 孔隙结构 致密化过程 抗氧化烧蚀性能 

分 类 号：TB332[一般工业技术—材料科学与工程]