Enhancing Initial Wettability between Molten Iron and Graphite via Metallic Interlayers

Achieving carbon neutrality in steelmaking necessitates the transition to electric arc furnaces, where the efficient dissolution of carbon injection (C-inj) materials into molten steel is critical for maximizing carbon utilization efficiency. However, conventional carbon materials exhibit poor wettability with molten iron, limiting their dissolution efficiency during the extremely short residence time (1-3 seconds) in industrial C-inj processes. This study investigated the enhancement of the initial wettability between molten iron and graphite through metallic interlayers using high-speed imaging to quantify the wetting behavior at timescales shorter than 0.1 seconds. When platinum (Pt) thin films were deposited on graphite substrates, contact angles dramatically decreased from approximately 110° (untreated graphite) to 53° at 0.5 seconds, establishing a wetted state immediately after contact. This rapid enhancement occurs through nonreactive wetting that develops immediately after contact between Pt and molten iron, preceding slower carbon dissolution reactions. Scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) analysis confirmed that the Pt films retained structural continuity after exposure to 1773 K, in contrast to the titanium (Ti) films, which became discontinuous due to agglomeration. Increasing Pt film thickness from 0.5 to 2.0 μm improved high-temperature coverage (40-54%), showing a positive correlation with wettability for both carbon-saturated and carbon-unsaturated iron. Critically, substantial improvements were achieved even with partial coverage, demonstrating practical feasibility. The results establish that metallic interlayers can rapidly control wettability within subsecond timescales by optimizing the interfacial energy during the initial nonreactive phase, providing a promising interfacial design strategy for carbon-efficient steelmaking applications.