Phase formation in Al2O3-C refractories with Al addition

Depending on the recipe and the firing conditions, several non-oxides can be formed in Al2O3-C refractories. In this paper, the effect of the purity of the recipe components on the phase formation in Al2O3-C refractories with Al addition was investigated. Two test series were sintered from 800 degrees C to 1600 degrees C under air embedded in coke breeze. One test series was with brown fused alumina, and the other was with tabular alumina. At temperatures of up to 1200 degrees C the phase formation was the same for both recipes. For temperatures greater than 1400 degrees C, the impurities of brown fused alumina enhanced the formation of a polytype, while Al4O4C and Al28O21O6N6 were formed in the other series. The findings explain the occurrence of several non-oxides in disequilibrium at the chosen temperatures. The occurrence of AI(4)C(3) was of particular interest due to its low hydration resistance. It was formed at 1200 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.