Original scientific paper
X-ray diffraction study of the process of graphitization
S. Popović
; Institute "Ruđer Bošković", Zagreb
Abstract
A series of samples of various crystallinity are obtained by heating of petroleum coke powder from 1000° C up to 3000° C. The temperature changes of the microstructural parameters are determined and the discussion about the gradual modulation of the diffraction lines during the process of graphitization is presented. By increasing the temperature above 1200° C the initial interlayer spacing d002 (3.47 A) decreases to the value (3.44 A) known as the spacing of the non-graphitic carbons. Above 1600° C d001 decreases very slowly and up to 2150° C the samples possess the random-layer structure. Above 2200° C the pairs of the nearest neighbour layers begin to take on the graphite relation and doo2 abruptly decreases. The ordering produces modulations in the twodimensional (hk) bands with the appearance of (hkl) reflections. A part of the volume retains the random-layer structure above 2200° C, without change of d002 and its proportion decreases from 15°/o at -2230° C to 50/o at 3000° C. In the whole temperature range the dimensions of the parallel layer groups normal to the layers (Le) and parallel to the layers (La) increase. The increasing of Le and La is especially pronounced above 1900° C and 2200° C, respectively. The averaged lattice distortion decreases ,with the temperature increasing, and the decreasing is the most important from 1600° C to 2100° C. In the beginning, the ordering of nearest neighbour pairs depends on the other neighbouring layers. The distribution of oriented and disoriented layers in the crystallites of the graphitic component is random above 2200° C.
Keywords
Hrčak ID:
320115
URI
Publication date:
23.11.1969.
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