Reaction of sintered spinel and corundum refractories with some compounds

Conclusions We investigated the reaction of sintered spinel, spinel-corundum, and corundum refractories with certain oxides at 1500–1750°C. We established conditions in which refractories are stable in respect to the action of individual oxides. We also investigated the mineral compositions of the reaction zones.The least reaction with all the oxides investigated occurs in the spinel refractory, and the greatest in the corundum; that is, there is an increase with rise in alumina content. Magnesia spinel hardly reacts with iron oxides in the test conditions.Magnesia spinel is very resistant to sodium adipates which extensively damage sintered corundum.Carbonates of alkali and alkaline-earth elements, and also fused alkalis at temperatures exceeding their melting points by 200°C seriously damage spinel-corundum refractories, but do not react with sintered corundum or spinel.Metallic fluorides damage corundum but do not react with spinel and spinel-corundum sintered refractories.Thus, spinel sintered refractory should find extensive use in conditions of corrosive action, in particular, alkalis and oxides of iron.Translated from Ogneupory, No. 1, pp. 37–42, January, 1968.     

Properties of refractories with ZrO2 and SIO2 added in different concentrations and by different means

Conclusions It has been established that the addition to corundum of 15–20% of a stoichiometric mixture of baddeleyite and quartz sand in both an unmilled and milled form increases by almost 1.5-fold (in relation to number of heat changes) the thermal-shock resistance of the refractory by comparison with a refractory containing 7.5–20% zircon.The addition of Novoselitsk kaolin is not effective. It has a bad effect on the characteristics of the corundum-zircon refractories.Translated from Ogneupory, No. 5, pp. 40–43, May, 1981.