Texture and graphitization behaviour of fluid coke

The texture, its changes with heat-treatments and with oxidation, and the graphitization behaviour of the fluid coke were investigated using polarized light microscopes, scanning electron microscopes and X-ray diffraction. The fluid coke as received had the homogeneous particle size of 0·1–0·2 mm. It consisted of two kinds of particles in almost equal amounts: one type with relatively smooth surfaces and showing crossed extinction contours for cross cuts, and the second type with very rough surfaces and radial extinction contours. In the former ones, the graphite-like layers seem to align approximately concentrically like that of onions. In the latter ones, regions with large graphite-like layers are highly oriented but those with small layers orient randomly being arranged like in a chrysanthemum flower. Formation of cracks in the particles heat-treated under normal pressure was observed and is explained as due to the texture. The graphitizability of the coke is very poor, c₀-spacing decreasing only to 6·78 Å after 2780°C-treatment under normal pressure and only to 6·82–6·84 Å after 2000°C-treatment under 5 kbar. The characteristic textures of the particles, onion- and chrysanthemum-like are still retained after heat-treatment under 5 kbar.