碳纳米管含量对炭炭复合材料组织及力学性能的影响

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。

Influence of Carbon Nanotube Content on Microstructures and Mechanical Properties of Carbon/Carbon Composite

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 CNT-reinforced carbon/carbon (C/C) composite. The influences of CNTs on microstructures and mechanical properties of 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 (F_D) 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.