Electrochemical Characterization of Cu-Induced Interfacial Behavior between a Molten Fe-Cu Alloy and Molten Oxide

The physical separation of miscible solute metals, such as Cu from molten iron, remains a formidable issue in steelmaking. In this work, we focus on a new strategy based on the electrocapillarity phenomenon to achieve selective removal of Cu from Fe-Cu melts. Electrochemical impedance spectroscopy (EIS) was conducted at 1873 K under an Ar atmosphere to investigate the interfacial behavior between Cu-containing molten iron and molten oxide. Increasing the Cu content increased the electric double layer capacitance, indicating greater interfacial charge accumulation. Electrocapillary analysis further showed a marked decrease in the interfacial tension under anodic polarization, especially at higher Cu concentrations, suggesting enhanced ion adsorption dynamics influenced by Cu. These experimental observations were supported by molecular dynamics simulations, which demonstrated that the aggregation of Cu atoms at the interface was driven by charge compensation. Although the charge transfer resistance was only slightly affected by the Cu content, the interfacial structure and electrochemical properties significantly changed. Overall, this combined experimental and computational approach provides new insights into the electrochemical tuning of molten metal-slag interfaces. These findings offer a promising basis for the development of next-generation Cu removal techniques that would contribute to more sustainable and efficient refining processes in scrap-based steelmaking.