Microscopy study of bonding in co-carbonizations between coke grist from coal-extract solution and coal-tar binder

Abstract

Optical microscopy and SEM examine coke composites from the co-carbonization at 673 K of coke grist (60%) from a coal-extract solution with Orgreave lean coal-tar pitch (40%) to study binding mechanisms. The coke grist was prepared at heating rates of 5–300 K h −1 to HTT of 800 K (one coke to 1200 K). It was found that the bonding was weak or non-existent using coke grist of heating rates 5 and 15 K h −1, but was significant using coke grist of heating rates 75, 150 and 300 K h −1 (except for coke of HTT 1200 K which showed poor bonding). These effects are discussed in terms of surface structure of the coke grist, possible influences of free-radicals (free-spins) and wettability associated with porosity.