以中间相沥青为粘结剂的低密度高导热炭纤维网络体的研究

以中间相沥青为粘结剂, 采用500 ℃低温炭化炭纤维, 经低压模压成型、炭化和石墨化后得到低密度高导热炭纤维网络体。与以1300 ℃炭化炭纤维为原料和以酚醛为粘结剂制备的炭纤维网络体进行了比较。对粘结剂炭收率(热重分析)、样品微观形貌(扫描电子显微分析)、石墨化度及微晶尺寸(X射线衍射分析)等进行了表征。研究结果表明: 由于高炭收率和高片层取向度的中间相沥青与500 ℃低温炭化处理炭纤维共同经历后续热处理时呈现出相近的热收缩率, 因而具备良好的相互粘结性和石墨片层铆接效应, 其制备的炭纤维网络体经石墨化后密度为0.317 g?cm ^-3, 由此制备的相变复合材料的面内热导率为19.30 W·m ^-1·K ^-1, 较纯相变材料(石蜡)提升了80倍, 明显高于以1300 ℃炭化炭纤维为原料, 以中间相沥青和酚醛分别为粘结剂制备样品的面内热导率(17.03和14.47 W·m ^-1·K ^-1)。

Evaluation of Low Density and Highly Thermal Conductive Carbon Bonded Carbon Fiber Network with Mesophase Pitch as Binder

The carbon bonded carbon fiber network was prepared by using carbon fibers carbonized at 500 ℃ with mesophase pitch as binder. The sample was compared with the one prepared by using carbon fibers carbonized at 1300 ℃and the one prepared by using phenolic resin as the binder. The carbon yields of binders, microstructure, graphitization degree and crystallite size of samples were characterized and thermal conductivity was obtained for the samples soaked into phase change materials (PCM) to form PCM composites. Results showed that a good “in-plane” bonding effect was formed between the highly aligned graphene layers of binders and graphite fibers. The density of the carbon fiber network after graphitization is 0.317 g?cm ^-3, and the in-plane thermal conductivity of its PCM composite is 19.30 W?m ^-1?K ^-1, increased by 80-folds as hhat of pure PCMs.