Synthesis of monophase Al4O4C and the effect of Al4O4C addition to MgO-C refractory

Monophase Al4O4C ceramic powder was synthesized using a mixture of α-alumina, carbon black and aluminum powders as raw materials. The effects of different starting compositions and raw materials ratio on the phase transformation and micromorphology of Al4O4C were investigated. The results indicated that α-alumina, carbon black and aluminum powders was more appropriate as raw materials, and 20 mol% excess of aluminum resulted in single phase Al4O4C. Al2OC would occur if excessive carbon black was used. The Al content was found to have a significant effect on the microstructure of synthesized Al4O4C. Al4O4C added to the MgO-C refractory initially reacts with CO to form Al2O3 and C. After the reaction, the formed Al2O3 will further react with MgO to form MgAl2O4. The above reaction processes can form protective layers on the surfaces of the refractories, which inhibit the oxidation of the refractories.