Influence of Slag Composition on Slag–Iron Interfacial Tension

Abstract

Interfacial tensions between liquid iron and slag were examined for CaO–SiO₂ binary and CaO–SiO₂–Al₂O₃ ternary slag systems. The influences of FeO, MgO, B₂O₃, TiO₂, BaO and ZrO₂ in slag on the interfacial tension were also investigated by varying these oxides from 1–30 wt% in the CaO–SiO₂ binary or CaO–SiO₂–Al₂O₃ ternary slag systems.
The interfacial tensions were determined by the sessile drop technique under argon atmosphere at 1 853 K. An X-Ray radiographic technique was employed to image the profile of molten iron drop in a slag bath and the interfacial tensions between slag and iron were obtained from the drop shape analysis.
In examining the effect of slag composition on the interfacial tension, the oxygen in liquid iron and its impact on the interfacial tension was taken into consideration. The interfacial tension was found slightly increased with increasing CaO/SiO₂ ratio in CaO–SiO₂ slag, and with increasing MgO content in the slag. A decrease of interfacial tension was found with increasing FeO in slag. Only minor changes in the interfacial tension were observed with varying the slag composition in the CaO–SiO₂–Al₂O₃ ternary slag system and the influences of B₂O₃, TiO₂, BaO, and ZrO₂ in slag on the interfacial tension were found insignificant.