Studies on phase formation in high alumina cement by varying manufacturing parameter and effect of those phases in refractory castable

Abstract

Unshaped refractories are superior over shaped refractories with respect of ease installation, durability, safety, cheaper, joint less or minimum joint structure and so on. In unshaped refractories, High- alumina cements (HACs) are the main binder and are currently most in demand. In the first generation of unshaped refractory the HACs were the one and only binding agent used. The good corrosion resistance and refractory properties of HAC account for its wide use in refractory concretes. The major mineral phases present in HACs are Monocalcium aluminate (CA), Monocalcium dialuminate (CA2), Dodecacalcium heptaaluminate (C12A7) and á-Al2O3. Depending on the prescribed setting times and mechanical properties of unshaped refractories in accordance with their application area, the quality or desired characteristics of HACs changes. All the properties of HACs depend only on its mineralogical phase composition. Just as CA phase is responsible for development of highest strength among all other Calcium Aluminate phases and relatively reduces the time during hydration. So for the achievement of desired characteristics or properties of the refractory or HACs the major concern must be taken in its phase composition. So in the present work attempt has been made to prepare HACs by varying operating parameter such as starting composition, raw materials and sintering temperature (during manufacturing) and study the effect of mineralogical composition of those cements on the properties of final product (refractory castable). In the preparation of HACs, alumina content and alumina sources (partially) were varied and sintering was done at two different temperatures 1430oC and 1470oC. Prepared HACs were characterized chemically & mineralogically (Phase Analysis). Castables were made by using those HACs and were characterized chemically and mechanically.