Mesophase microspheres from distillation and thermal treatment of coal tar
We have investigated the formation of mesophase carbon microbeads in tar pitch generated by the coal coking in a steelmaking plant. Pitches were obtained at different distillation temperatures (643, 673 and 723 K). The distilled samples were then thermally treated in nitrogen atmosphere either at 723 K for 8 h (T1) for at 703 K for 4 h (T2). A new phase appears, seen in optical microscopy with a polarizing filter. Samples subjected to the T1 thermal treatment were found to form a discontinuous fluid phase distinct from the main phase.