Texture and Graphitizability of Gilsonite Coke

Abstract

The texture of gilsonite coke and its change with heat treatment were investigated with scanning electron and polarized light microscopy. The graphitizability of the coke was examined after heat treatments under normal pressure and high pressure of 5 kbar.Gilsonite coke consisted of spherical particles of less than 1 mm in diameter, in which graphite-like carbon layers roughly aligned concentrically and a number of concentric thin cracks and large pores around the center of the particles were observed. After 2800°C-treatment under normal pressure, concentric cracks were difficult to be found and the matrix seemed to be densified. The texture of gilsonite coke was found to remain even after heat treatment under high pressure. Under high pressure, the coke was only partly graphitized, although non-graphitizing phenol resin char was perfectly graphitized under the same condition. The present result shows the importance of the texture in raw carbon materials for the graphitization under pressure.