Abstract
The relations among X-ray parameters, c0, Lc (002), Lc (004), La (110) and Lc (112), were investigated on a petroleum coke heat-treated in the flow of nitrogen and under reduced pressures of 0.1, 2 and 4Torr. at various temperatures and residence times. The strain along the c-axis, εc, was calculated from the slope of the plot of 1/Lc (00l) vs. l. From these experimental data, the graphitization process of the petroleum coke seemed to be divided into at least two stages. In the first stage, the mean lattice spacing c0, is larger than 6.85Å and the strain εc decreases remarkably with heat treatment. In the second stage, c0 is smaller than 6.85Å, the apparent crystallite size Lc (00l) increases and εc decreases gradually with heat treatment. The modulation of (hk) diffraction band, for example (11) band, begins to appear, i.e. the three-dimensional graphite structure begins to develope, from the beginning of the second stage. These two stages of graphitization process correspond well to those proposed by other authors. The difference in heat treatment has no detectable effect on the relations among X-ray parameters of the coke.
