Antioxidation Behavior and Effect of Al8B4C7 Added to Carbon-Containing Refractories.

Abstract

The behavior of Al8B4C7 in CO(g) and its effect as an antioxidant in both Al2O3-C and MgO-C have been investigated, and the corresponding mechanisms have been discussed. Al8B4C7 markedly inhibits the oxidation of the carbon-containing refractories. The added Al8B4C7 reacts with CO(g) quickly above 1400°C to give B2O3. The B2O3 further reacts with MgO or Al2O3 in the refractories to form Mg3B2O6 or Al18B4O33. Mg3B2O6 is stable till 1400°C in air, but Al18B4O33 begins to decompose above 1300°C. Al8B4C7 is more effective as an antioxidant in MgO-C refractories than in Al2O3-C refractories, due to the different stability characteristics of Mg3B2O6 and Al18B4O33.