碳纳米管含量对炭炭复合材料组织及力学性能的影响

摘要

炭纤维上原位合成了均匀生长且具有伸张形貌的碳纳米管,借助化学气相渗透制备了碳纳米管增强的炭炭复合材料,研究了不同含量的碳纳米管对炭炭复合材料组织和力学性能的影响.结果表明:炭纤维上生长碳纳米管改变了热解炭的沉积行为,诱导了各向同性热解炭的生成,且随着碳纳米管含量的增加,各向同性热解炭的厚度增加,但是复合材料的d002值却明显降低.微量的碳纳米管即可显著提高复合材料的力学强度,随着其含量的增加,复合材料的力学强度和模量迅速提高,但材料的断裂行为却急剧恶化,断裂模式由最初的假塑性断裂转变为脆性断裂.%Carbon nanotubes (CNTs) with a uniform growing and extending morphology were in situ grown on carbon fibers in carbon felt and then chemical vapor infiltration (CVI) was used to densify the felt to get a CNTreinforced carbon/carbon (C/C) composite. The influences of CNTs on microstructures and mechanical propertiesof C/C composite were investigated by varying CNT content. The results show that a layer of isotropic (ISO)pyrocarbon is deposited closely around carbon fibers after growing CNTs and this zone becomes extended with CNTs increase, while the d002 value of pyrocarbon decreases for CNT-related composites remarkably. Compared with pure C/C composite, CNT-reinforced C/C composites have much higher mechanical strength and modulus.However, with CNTs increase, the ductility of the composite deteriorates gradually according to the decrease of ductility factor (FD) value and the fracture mode changes from pseudo-plastic fracture to brittle fracture in spite of the sharp increase in both mechanical strength and modulus.