Study on the mechanism of external current inhibiting the adsorption of rare earth inclusions in molten steel by aluminum and magnesium refractory

This study aims to reveal the intrinsic mechanism by which external positive charge inhibits the adsorption of rare earth Y-based inclusions (Y, Y₂O₃, Y₂O₂S) on MgO and Al₂O₃ refractory surfaces, thereby providing a theoretical foundation for the active control of nozzle clogging during the continuous casting of rare earth steels. To this end, first-principles calculations based on density functional theory were employed, integrated with partial density of states analysis, charge density difference visualization, and high-temperature thermodynamic evaluations. The adsorption behaviors under neutral and positively charged states (+ 2, + 4) were systematically compared. The results demonstrate that external positive charge suppresses interfacial adsorption through a triple mechanism. Electronically, it disrupts the energy alignment and orbital hybridization between O-p and Y-d states, leading to significant attenuation of interfacial covalent bonding. Electrostatically, the net positive background reverses the local interfacial environment from electrostatic affinity to repulsion, establishing a physical barrier that hinders adsorbate approach. Thermodynamically, the Gibbs free energy change ΔG increases markedly under charged conditions, reflecting a quantifiable and universal reduction in adsorption spontaneity across all adsorbates and substrates. These findings clarify the mechanism of external charge inhibiting the adsorption of rare earth inclusions in molten steel by refractory.