Electrochemical method for controlling the interfacial oxygen in molten Fe with ZrO₂ based solid electrolyte

The control of the interfacial oxygen concentration in molten steel by an electrochemical method using ZrO₂ based solid electrolyte was suggested in this study. Oxygen ions were transferred through the solid electrolyte by varying the chemical potential difference and applying an external electric potential between the cathode and the anode. By applying an external electric potential, the oxygen concentration was controlled below 3 ppm at the molten Fe/ZrO₂ interface. The electrochemical reaction rate of oxygen removal was found to be faster than the estimated diffusion of oxygen through the boundary layer of molten steel. Thus, the slow diffusion of oxygen through the boundary layer creates a steady state oxygen concentration profile, where an oxygen depleted layer at the molten Fe/ZrO₂ interface is present. The oxygen concentration profile in the boundary layer was confirmed using the Glow Discharge Spectroscopy. In this study, the oxygen concentration at the interface could be controlled using an electrochemical method of ZrO ₂ based solid electrolyte and achieve a steady state at the interface within the liquid phase boundary layer.