高定向炭纤维及其高导热炭/炭复合材料的控制制备与导热机理研究

In this project, the controlling preparation of highly oriented ribbon-shaped and round-shaped carbon fibers and the thermal conduction mechanism of high thermal conductivity carbon/carbon composites will be investigated.The controlling preparation of ribbon-shaped and round-shaped pitch fibers with liquid crystalline orientation along fiber longitudinal direction will be explored by a melt-spinning method from a liquid crystalline mesophase pitch by adjusting and controlling the preparation parameters. Through oxidation stabilization as well as further carbonization and graphitization treatment, millimeter-wide carbon fiber tapes with carbon layers oriented perpendicular or parallel to the main plane of fiber tapes, and carbon fibers with carbon layers along fiber longitudinal direction can be prepared. Using the ribbon-shaped or round-shaped carbon fibers as a reinforcement and different types of pitches as binder, the carbon/carbon composites with thermal conductivity over 800 W/m K or 700 W/m K in the direction parallel to fiber longitudinal direction will be prepared by hot-pressing, carbonization and graphitization processes. In order to clarify the thermal conduction mechanism of of carbon fibers and their composites, the effects of the crystalline orientation, microstructure and texture of carbon fibers with round section and rectangle section on the thermal conductivity of carbon fibers and their composites will be investigated systematically. The relationship between the thermal-electrical transport properties of carbon fibers and the thermal and mechanical properties of their composites will be disscused to achieve the optimization of preparation process. Based on the above investigations, a set of manufacturing process and control technique for carbon fibers and carbon/carbon composites with high thermal conductivity will be suggested, which will lay the theoretical and technical groundwork for their industrial manufacture and application.

本项目围绕高定向带状和圆形炭纤维及其高导热炭/炭复合材料的控制制备与导热机理展开研究。以液晶中间相沥青为原料，通过沥青熔融纺丝制备带状和圆形截面沥青基纤维；随后对沥青纤维进行预氧化、炭化和石墨化处理制备出碳层片取向垂直或平行于纤维带主平面的毫米级炭纤维带和沿纤维长度方向的炭纤维；并将纤维带或纤维与不同沥青粘结剂进行复合，再经炭化和石墨化热处理得到单向热导率分别大于800W/m.K或700W/m.K的高导热炭/炭复合材料。为阐明炭/石墨纤维及其复合材料内部的传热机理，系统研究制备工艺对圆形截面和矩形截面炭纤维晶体取向和微观结构的影响，并与纤维的导电和导热性能以及炭/炭复合材料的导热性能和力学性能相互关联实现制备工艺优化。形成一套完整的从纤维带/纤维纺丝、预氧化和炭化/石墨化、纤维带复合以及高导热炭/炭复合材料的制备和调控技术，为高导热炭/炭复合材料的工业化制备和应用奠定理论和技术基础。

随着科学技术的飞速发展，高效导热和散热成为热管理领域的关键问题。对热管理材料来说，最重要的性能要求是材料具有较高的比热导率，炭（石墨）材料的特殊结构和性能可以满足要求。通过控制炭材料（如炭纤维）内部的石墨微晶尺寸及其连续择优取向，就能提高炭材料沿此方向的热导率，从而满足热管理领域的迫切需求。.本项目围绕高定向带状和圆形炭纤维及其高导热炭/炭复合材料的控制制备与导热机理展开研究。以萘系液晶中间相沥青为原料，通过沥青熔融纺丝制备带状和圆形截面沥青基纤维；随后对沥青纤维进行预氧化、炭化和石墨化处理制备出碳层片取向垂直或平行于纤维带主平面的毫米级炭纤维带和沿纤维长度方向的炭纤维；并将纤维带或纤维与不同沥青粘结剂进行复合，再经炭化和石墨化热处理得到单向热导率分别大于800W/m.K或700W/m.K的高导热炭/炭复合材料。为阐明炭/石墨纤维及其复合材料内部的传热机理，系统研究制备工艺对圆形截面和矩形截面炭纤维晶体取向和微观结构的影响，并与纤维的导电和导热性能以及炭/炭复合材料的导热性能和力学性能相互关联实现制备工艺优化。.本项目形成一套完整的从纤维带/纤维纺丝、预氧化和炭化/石墨化、纤维带复合以及高导热炭/炭复合材料的制备和调控技术，为高导热炭/炭复合材料的工业化制备和应用奠定理论和技术基础。作为本项目研究的延伸和扩展，项目组还对中间相沥青基炭纤维的化学反应性及其电化学性能进行了研究，以期拓展其应用领域。