Sintering of powders of polyaromatic mesophase to high-strength isotropic carbons .3. Powders based on an iron-catalyzed mesophase synthesis

A spherulitic mesophase pitch with about 50 vol% mesophase has been synthesized by an iron-catalyzed pyrolysis of a coal tar pitch. The isotropic pitch is removed to various extents by solvent extraction. The thermoplasticity of the resulting raw mesophase powders is adjusted by treatment with oxygen with respect to optimum sintering properties. After milling of these powders to a particle size d less than or equal to 10 mu m they were compacted with various molding pressures, sintered and graphitization-treated with various heating programs. The individual process steps and intermediate products were analyzed. Carbons sintered at 1300 degrees C show flexural strengths up to 225 MPa and strains-to-failure up to 1.25%. After graphitization treatment at 2400 degrees C, carbons with a flexural strength of about 170 MPa and a strain-to-failure of about 1% were obtained. Copyright (C) 1996 Elsevier Science Ltd