SINTERING OF POWDERS OF POLYAROMATIC MESOPHASE TO HIGH-STRENGTH ISOTROPIC CARBONS .1. INFLUENCE OF THE RAW-MATERIAL AND SINTERING CONDITIONS ON THE PROPERTIES OF THE CARBON MATERIALS

The sintering of compacted mesophase powders of varying nature and par ticle size was studied. The sintered carbons were stepwise heat-treate d to 2600-degrees-C, and their properties were determined after each s tep. The sintering process is composed of a transient liquid-phase sin tering step and a subsequent reaction sintering step in the solid stat e. The investigation of both process steps and the properties of the h eat-treated carbons indicate that the initial transient liquid-phase s intering is the decisive step, and thus predetermines the properties o f the heat-treated carbons. After graphitization treatment of sintered carbons at 2400-degrees-C, flexural strength values up to 160 MPa wer e obtained. Criteria for the selection of the mesophase, the particle size, and the sintering conditions are discussed.