Interfacial tension between molten iron and CaO-SiO2-MgO-Al2O3-FeO slag system

Abstract

The interfacial tension of the CaO-Al2O3-SiO2-MgO-FeO slags with liquid iron at 1550 degrees C was investigated using a synchrotron X-ray beam source. The interfacial tensions of molten slag with liquid iron increased continuously with increasing CaO/SiO2 ratio for both CaO SiO2-MgO and CaO-SiO2-Al2O3-MgO slag systems. However, the contents of MgO and Al2O3 exceeded the saturation limit and the apparent interfacial tension decreased markedly. This decrease was attributed to formation of a solid phase at or near the interface: MgO particles for MgO saturation and MgAl2O4 particles for Al2O3 saturation. It was found to be oxygen in iron that exerts a dominating influence on the interfacial tension. Its influence was so dominant that all other compositional effects were insignificant. The effect of oxygen was quantitatively determined by employing the Gibbs adsorption and Langmuir isotherms.