借助偏光显微镜、扫描电镜、透射电镜以及力学性能测试研究了微观结构对中间相沥青基炭/炭复合材料力学性能的影响. 结果表明: 基体炭在偏光显微镜下呈现出光学各向异性, 在SEM和TEM下呈片层条带状结构. 基体炭与纤维之间的界面不连续, 为“裂纹型”界面. 材料受载破坏时裂纹通过改变扩展路径而延缓其扩展速度, 在纤维-基体界面处以及基体炭层片之间引起滑移, 在断口形貌上体现出断裂台阶适中且与纤维拔出交替进行, 表现出韧性破坏的断裂特征. 材料具有较高的力学性能, 抗弯强度达到257MPa, 断裂韧性达到11.4MPa·m ^1/2.

The effect of microstructure on the mechanical properties of 2D PAN fiber reinforced mesophase pitch-based carbon/carbon (C/C) composites was studied by polarized light microscope (PLM), scanning electron microscope (SEM), transmission electron microscope (TEM) and mechanical properties test techniques respectively. PLM results indicate that the structure of the mesophase pitch matrix is graphitic and anisotropic. TEM and SEM results show the mesophase pitch matrix is the lamellae layer structure and the fiber-matrix interface morphology is similar to the "fissured-type 〞interface. The non-brittle fracture behavior of the composites is related to multiple crack deflections caused by the fiber-matrix interface and delamination microcracking within the pitch carbon layers. The fractured surfaces are made of fracture and pulling out of fiber. The flexural strength and the fracture toughness (K_IC) of C/C composites are 257MPa and 11.4MPa·m ^1/2, respectively.