THE ROLE OF CARBON IN REFRACTORIES

Some of the scientific principles underlying the role of carbon and graphite in graphitic refractories are considered, with emphasis on the graphite phase. The highly anisotropic nature ofgraphite is a key factor in its ability to modify the properties of oxide refractories, resulting in the potential for anisotropy in the subsequent graphitic composite, depending upon the fabrication conditions. The thermal and mechanical properties are considered for model alumina-graphitecomposites first with no anti-oxidant additives in the formulation to reveal the intrinsic effect ofthe graphite phase and then effects of silicon as a typical additive are examined. The behaviour is modified considerably when the extent of ceramic bonding in the materials is increased through the reactions of silicon with the gaseous atmosphere and with the constituents in the refractory. Finally, a brief consideration of the structure and properties of typical binder phases is presented.