炭化过程中的磁场作用对针状焦结构及导电性能的影响

摘要

The influence of a magnetic field during thermal polycondensation and carbonization of intermediate coal tar pitch on the electrical conductivity of the resulting needle cokes was explored using a pressure vessel under an external magnetic field. The microstructure of the cokes was analyzed by X-ray diffraction and polarized light microscopy. The electrical conductivity was measured during the coke forming process. Results indicated that aromatic molecules were ordered under the magnetic field during carbonization, leading to an improvement in the microcrystailine structure and an increase in the electrical conductivity of the cokes. Resistance-temperature curves also indicated that the magnetic field can accelerate the polymerization rate and reduce the dependence of the polymerization on temperature, which can be explained by the Zeeman effect.%以中温煤沥青为原料,在载磁压力反应釜中进行热缩聚炭化合成针状焦;采用在线电阻测量法测定针状焦形成过程中磁场对电导的影响规律;通过偏光显微镜及X射线衍射仪对产物的形貌和组织结构进行表征.结果表明:外加磁场对于改善针状焦微结构具有显著的作用,并能有效提高针状焦的电导特性,减小制备过程对温度的依赖性;适宜的压力有利于热缩聚反应的进行,提高成焦的收率;磁场还可以通过塞曼效应对自由基产生影响,提高自由基有效利用率,加快聚合反应速率;在磁场与压力的协同作用下,针状焦的石墨化性能也获得大幅度提升.