Abstract The catalytic graphitization process of coke carbon with iron was investigated in the temperature range of 1100 °C–1500 °C using X-ray diffraction, scanning electron microcopy, high-resolution transmission electron microscopy (HRTEM). The evolution of micro-crystal graphite lattice fringes was carefully analyzed by image processing of the HRTEM micrographs. A strong catalytic effect of iron on graphitization was observed at temperature above 1200 °C with an obvious increase of carbon structural orders. Iron was found to promote the decrease of d0 0 2 value and increase of Lc values of the turbostratic carbon, while the d0 0 2 value of the newly formed graphitic carbon is quite below that of the commercial graphite when it just forms at 1200 °C. The melting point of iron particles were decreased due to the significant carbon dissolution into iron, leading to the melting and aggregation of iron. The lattice fringe length and the stacking number of micro-crystal graphite were found to increase obviously, while no clear change of crystal orientation was observed. This indicates that the growth of micro-crystal graphite was along its original orientation. The carbon dissolution – graphite precipitation mechanism can be used to explain the catalytic graphitization process very well.

中文翻译：

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铁催化焦炭碳石墨化：了解碳结构、形态和晶格条纹的演变

摘要 使用 X 射线衍射、扫描电子显微镜、高分辨透射电子显微镜 (HRTEM) 研究了焦炭与铁在 1100 °C–1500 °C 温度范围内的催化石墨化过程。通过 HRTEM 显微照片的图像处理仔细分析了微晶石墨晶格条纹的演变。在1200℃以上的温度下观察到铁对石墨化的强烈催化作用，碳结构顺序明显增加。发现铁促进了乱层碳的 d0 0 2 值的降低和 Lc 值的增加，而新形成的石墨碳的 d0 0 2 值远低于商业石墨在 1200 °C 下刚形成时的值. 由于大量的碳溶解到铁中，导致铁的熔化和聚集，铁颗粒的熔点降低。发现晶格条纹长度和微晶石墨的堆积数明显增加，而没有观察到明显的晶体取向变化。这表明微晶石墨的生长是沿着它原来的方向生长的。碳溶解-石墨沉淀机理可以很好地解释催化石墨化过程。