Effect of iron oxides on mullite-corundum refractories under the conditions of oxidizing and reducing media

The interaction of mullite-corundum refractories with iron oxides in an oxidizing medium results in the formation of solid solutions in mullite and corundum. When fired in a reducing medium the solid solutions decompose with disruption of the structure and loosening of the refractory. Repeated heat cycles in different gaseous media lead to a periodic change in the phase composition of the refractory and worsen its quality and hence its stability in service.Translated from Ogneupory, No. 5, pp. 22 – 24, May, 1995.