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 sy nthesized by an iron-catalyzed pyrolysis of a coal tar pitch. The isot ropic pitch is removed to various extents by solvent extraction. The t hermoplasticity of the resulting raw mesophase powders is adjusted by treatment with oxygen with respect to optimum sintering properties. Af ter milling of these powders to a particle size d less than or equal t o 10 mu m they were compacted with various molding pressures, sintered and graphitization-treated with various heating programs. The individ ual process steps and intermediate products were analyzed. Carbons sin tered at 1300 degrees C show flexural strengths up to 225 MPa and stra ins-to-failure up to 1.25%. After graphitization treatment at 2400 deg rees C, carbons with a flexural strength of about 170 MPa and a strain -to-failure of about 1% were obtained. Copyright (C) 1996 Elsevier Sci ence Ltd