Wetting and spreading behavior of molten iron in contact with graphite substrate: Interfacial effects

Abstract

The dissolution of carbon from coke into molten iron is a critical factor influencing melting efficiency and lining erosion of blast furnaces. To gain an in-depth understanding of this process, the wetting and spreading behaviors of molten iron in contact with a graphite substrate were studied using high-temperature vacuum wettability test equipment and a microstructural analysis method. The results show that the initial contact angles of molten iron on a graphite substrate (105.8°, 116.7°, 122.0°) and the equilibrium contact angles (60.6°, 65.4°, 70.7°) increase with increasing initial carbon content (Fe-3.8%C, Fe-4.3%C, Fe-4.8%C), showing a certain dependence on the carbon content in the molten iron. The initial stage of interaction between the molten iron and graphite substrate is a non-wetting state, which transitions to a wetting state during the spreading stage at high temperatures. A spherical cap structure is formed because of interfacial effects. The results show that the penetration of carbon into the molten iron decreases with increasing initial carbon content. Finally, the wetting and spreading mechanisms are illustrated on the basis of interfacial energy analysis. It is mainly controlled by dissolution in the initial stage of wetting and spreading, then transfers to reaction-driven control.