DEMONSTRATION OF SPONTANEOUS LIQUID-PHASE SINTERING OF MESOPHASE POWDERS

Pellets of a commercially available mesophase powder suitable for the production of fine-grained carbons were shock-heated at 2 and 5 MPa inert gas pressure up to temperatures between 300 and 500-degrees-C. After treatment times between 10 and 60 s, the material was rapidly cooled down. For these treatments the Curie point technique was used. The formation of sintering bridges as a consequence of the treatment was studied with scanning electron microscopy. Liquid-phase sintering occurred at 400-degrees-C and 60 s (2 MPa) and at 300-degrees-C and 30 s (5 MPa). From these results it was concluded that liquid-phase sintering by viscous flow can be a spontaneous process, provided that the conditions are adequate to retain the flow properties to permit sintering before hardening stops the process.