含有大量液晶分子的中间相沥青是制备轴向高导热炭/炭复合材料的重要原料,以中间相沥青基炭纤维为增强体与中间相沥青基体经液相浸渍法制备高导热炭/炭复合材料.中间相沥青基体随着热处理温度不断升高逐渐转化为包含诸多缺陷的石墨晶体,这些缺陷对复合材料的热传导有较大影响.利用透射电子显微镜研究中间相沥青基石墨晶体中的缺陷结构,尤其是不完整石墨晶体[11-20]晶带轴衍射谱中(10)列衍射斑点拉线的成因.结果表明,中间相沥青基体经3 000 ℃热处理后主要形成六角石墨,但六角石墨主体中夹杂数层菱形石墨,进一步发现,够成(10)列衍射拉线的缺陷主要包括两类:层错(基面间不同程度位移形成的位移缺陷)和晶界(相邻晶粒间相互旋转形成的旋转缺陷以及非共格晶界).
A C/C composite as a thermal conducting material was prepared by the impregnation of unidirectional mesophase pitch-based carbon fibers with mesophase pitch and graphitization at 3 000 ℃.It was thinned to around 10 nm in the direction parallel to the fiber axis by cutting, grinding and ion beam bombardment.Results indicate that mesophase pitch is transformed into hexagonal graphite (HG).However, there is rhombohedral graphite (RG) tens of nanometer thick mingled with the HG.Defects include the glide and rotation structures and grain boundaries.
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