Modification of the sintering behaviour of mesophase powder from a petroleum residue

The effect of preparation conditions on the sintering behaviour of different binderless polyaromatic mesophase (BPAM) powders, obtained by extraction with different solvents of four petroleum semicokes of increasing carbonisation degree, is described. The analyses of the powders indicate that large differences in composition and structure are obtained when changing the semicoke. Increasing carbonisation degree of the semicoke produces a decrease in the amount of β-resins, increase in mesophase content, C/H ratio and aromaticity, but decreases the thermofusibility of BPAM. Increasing extraction strength of the solvent reduces the amount of light material, and thermofusibility of BPAM, being more evident with low carbonised semicokes. Selection of carbonisation conditions and solvent permits to adjust fusibility of the powders and to improve sintering. Graphitised compacts exhibited the best properties when they are produced from low carbonisation degree semicokes. In this case solvents of low extraction strength provide large thermofusibility to the material, and compacts may swell. When using semicokes of higher carbonisation degree there is a reduction of the sintering abilities of the powders, this being more evident as the strength of the solvent increases.