Wetting and interfacial tension of molten CaO–Al2O3–MgO–FeO slag and BN substrate

Abstract

The interface characterization is one of the important properties of molten slag, which has a significant influence on the interface phenomenon of molten slag and the reaction between slag and metal. The wettability of molten CaO–Al2O3–MgO–FeO slag on BN substrate was investigated in a wide range of temperatures from 1673 to 1773K. The FeO content was varied from 0 to 15 wt%. The contact angle was measured by the sessile drop method, the surface tension and interfacial tension were calculated by Dorsey method and Young's equation, respectively. The effects of the FeO content and temperature on the contact angle, surface tension and interfacial tension were discussed. The results indicated that the initial contact angle decreases with the increase of temperature and FeO content. And the wetting reaction between BN substrate and the selected molten slag is non-reactive wetting. The surface tension of the selected molten slag is in the range of 586–616 mN/m, and the surface tension decrease with the increase of FeO content and temperature. The value of interfacial tension between the selected molten slag and BN substrate is close to that of the surface tension, and the interfacial tension is 211–375 mN/m. The trend that the interfacial tension changes with the FeO content and temperature was the same as the trend that surface tension changes with the FeO content and temperature. Changes in the interfacial tension were correlated with modifications in the slag structure when FeO is added. The interfacial tension linearly decreases with increasing the optical basicity, which can provide a global measure of the concentrations of free oxygen ion in molten slag.