The role of graphite and B_4C on the technological properties and oxidation resistance of AMC and MAC refractories

摘要

Two series represent AMC (Alumina-Magnesia-Carbon) and MAC (Magnesia-Alumina-Carbon) denoted as Mix1 and Mix2 were dry mixed with different proportions of graphite up to 20 wt. percent and fired at 1580 deg C for 4 hours in reducing atmosphere. The effect of graphite addition on their physical properties as B.D., A.P. and linear change as well as technological properties as refractory (TSR, RUL) and mechanical (CCS) was also studied. Two selected batches for each series were mixed with 1-2 wt. percent B_4C and also fired up to 1580 deg C then subjected to further study by measuring the technological properties as BD, AP, CCS and refractory properties. Also, oxidation resistance, phase composition in addition to microstructure and microchemistry were investigated. It is observed that the addition of 5 wt. percent graphite and 1-2 wt. percent B_4C on the two series enhanced the physico-mechanical properties as well as the oxidation resistance of both AMC and MAC refractories due to the formation of low melting borate phases.