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本文应用广角X射线散射径向分布函数(RDF)法对三种典型的不可石墨化碳的结构及其随温度的转化进行了研究。在使用“去负法”对RDF进行截尾效应校正时,对Kaplow等的方法作了修正,发展成为“小r区降零过正法”,由自编的计算程序得到了不可石墨化碳的RDF,结果较为满意。由RDF曲线取得的基本结构参数是表征不可石墨化碳结构带本质性的基本数据。研究表明,在被测定的三种不可石墨化碳中,除主要为sp~2杂化键的石墨层片结构外,还存在着显著含量的sp~3杂化轨道碳一碳键。这说明,具有四面体结构的碳一碳交联键将芳香结构的层片状分子彼此联接,以及这些碳原子以层片内部缺陷处的sp~3杂化的间隙原子形式,存在于这三种不可石墨化碳中。其中,聚丙烯腈(PAN)基碳纤维在原子空间排布上受到原丝纺丝过程中拉伸张力的影响,而碳黑则受缺陷原子及层面皱折的制约,玻璃碳则由于乱带型碳网骨架的存在,形成了多微孔、低密度的结构特征。
In this paper, the structure of three typical non-graphitizable carbons and their transformation with temperature were studied by using wide-angle X-ray scattering radial distribution function (RDF). When using the “to go negative method” to correct the censoring effect of RDF, the method of Kaplow et al was revised and developed into a “small r region drop zero overcorrection method”, and the non-graphitizable carbon RDF, the result is more satisfied. The basic structural parameters obtained from the RDF curve are the basic data for characterizing the essential non-graphitizable carbon structure. The results show that there are significant sp ~ 3 hybrid orbital carbon-carbon bonds in the three kinds of non-graphitizable carbons, except for the graphite layer structure of sp ~ 2 hybrid bond. This shows that carbon-carbon cross-linkages having a tetrahedral structure associate the lamellar molecules of the aromatic structure with each other and that these carbon atoms exist as sp ~ 3 hybrid interstitial atoms in the interior of the lamellae in these three Non-graphitizable carbon. Among them, the polyacrylonitrile (PAN) -based carbon fibers are affected by the tensile tension in the spinning process of the precursor in the atomic space arrangement, while the carbon black is restricted by the defect atoms and the layer wrinkles. The existence of carbon network skeleton, forming a multi-microporous, low-density structural features.