高导热中间相沥青基炭纤维的微观结构研究

Microstructure of high thermal conductivity mesophase pitch-based carbon fibers

摘要: 本文研究了高导热（500~1127 W·m⁻¹·K⁻¹）中间相沥青基炭纤维的微观结构特征，初步建立了微观结构特征与导热性能之间的影响关系。通过XRD、拉曼光谱、SEM和TEM对纤维的显微结构进行了系统表征，结果表明，辐射状的纤维结构热导率较高，并伴随着劈裂状结构特征。La对热导率的影响比Lc更加显著，纤维截面上的R值可作为评估热导率的重要参照指标。在本研究所涉及的纤维中，石墨微晶尺寸越大，微晶缺陷越少，石墨微晶片层沿纤维轴向取向度越好，则炭纤维的热导率越高。

Abstract: The microstructural characteristics of high thermal conductivity mesophase pitch-based carbon fibers were investigated by XRD, Raman spectroscopy, SEM and TEM. The relationship between microstructural characteristics and thermal conductivity is discussed. Results show that the radial structure is always accompanied by a splitting stucture. La has more significant impact on the thermal conductivity than Lc. The Raman spectroscopy I_D/I_G value of the cross section was used as an essential index to evaluate the thermal conductivity of the carbon fibers. The microstructural characteristics including large graphite crystallite size, high preferred orientation along the fiber axis, and few defects contribute to the high thermal conductivity of the carbon fibers.