【摘要】 以大直径(40~50μm)中间相沥青基炭纤维为导热相,以掺杂一定量不同粒径天然鳞片石墨的中间相沥青为黏结剂,经500℃热压成型、高温炭化及石墨化处理制备出单向高导热炭/炭(C/C)复合材料。采用偏光显微镜和扫描电子显微镜对复合材料石墨化样品的形貌和微观结构进行表征,并探讨鳞片石墨掺杂对复合材料不同方向导热性能的影响。结果表明,掺杂鳞片石墨对复合材料的体积密度影响较小,但对复合材料不同方向的导热性能有显著影响,复合材料沿纤维长度方向的室温热扩散系数随鳞片石墨体积分数和粒径的增加而减小,而垂直纤维长度方向的室温热扩散系数呈现上升趋势;添加16 vol.%粒径约为60μm的鳞片石墨所制复合材料沿纤维长度方向热扩散系数由掺杂前的650.5 mm~2/s降至510.9 mm~2/s,下降了21%,而垂直纤维长度方向的室温热扩散系数由22.4 mm~2/s提高到48.9 mm~2/s,增加了118%。掺杂鳞片石墨明显提高了复合材料垂直纤维长度方向的导电性能和抗弯性能。更多还原

【Abstract】 Unidirectional carbon/carbon composites were prepared by hot-pressing mesophase pitch-based carbon fibers as the conductive filler phase and mesophase pitch containing natural flake graphite as the binder/matrix at 500 ℃ followed by carbonization at 1000 ℃ for 1 h and graphitization at 2900 ℃ for 1 h. The morphology and microstructure of cross-sections of the samples were characterized by polarized-light microscopy and scanning electron microscopy. The effect of adding natural flake graphite to the mesophase pitch on the thermal conductivity of the composites was investigated. Results showthat the graphite addition has little effect on the bulk densities of the composites,but has a significant impact on the thermal conductivities in different directions. With increasing the graphite content and particle size,the thermal diffusivity of the composites in the longitudinal direction of the fibers decreases while that in the perpendicular direction increases. With a graphite addition of 16 vol% and an average graphite particle size of 60 μm,the longitudinal thermal diffusivity of the composite decreases from 650. 5 to 510. 9 mm~2/s while the perpendicular thermal diffusivity increases from 22. 4 to 48. 9 mm~2/s. The flexural strength of the composites perpendicular to the fibers is also increased by 29% by adding graphite.更多还原