Effects of interfacial properties between molten iron and alumina on neck growth of alumina balls at sintering in molten iron

Abstract

The effects of interfacial properties such as interfacial tension and wettability on the adhesion, agglomeration, and coalescence of inclusions on the immersion nozzle in a continuous casting process have not yet been evaluated quantitatively. In the present work, we focused on the neck growth of alumina balls at sintering because the adhesion, agglomeration, and coalescence of inclusions are regarded as being the consequence of sintering of oxides. We compared the neck growth of alumina balls at sintering in molten iron with that under an Ar gas atmosphere in order to clarify the effects of interfacial properties between alumina balls and molten iron on the sintering of alumina balls in molten iron. We found that neck growth in molten iron proceeds much faster than that under an Ar gas atmosphere. In addition, an equation for the neck growth of alumina balls in molten iron was formulated by evaluating the interfacial properties, i.e., the interfacial tension and wettability, between alumina balls and molten iron. The calculated results derived by considering the capillary phenomena of molten iron at the gap between alumina balls as the effect of wettability were in reasonable agreement with the experimental results in molten iron. These findings show that the non-wetting by molten iron of alumina balls promotes neck growth of alumina balls at sintering in molten iron. © 2014 ISIJ.