A Study on the Electrochemical Deoxidation Using ZrO₂ Based Solid Electrolyte and a Periodic DC Voltage

Abstract

An electrochemical deoxidation using a ZrO2 based solid electrolyte was investigated to control the interfacial oxygen concentration between the molten steel and ZrO2. The electrochemical deoxidation cell consisted of an MgO stabilized ZrO2 and an external power supply. In a previous study with constant external DC voltage, the oxygen concentration at the interface between the solid electrolyte and the molten steel was decreased to 2.2 ppm, which was the limit caused by the cathodic over‐potential when a constant external DC voltage was applied. In the present study, a novel process of using a periodic or cyclic voltage for the electrochemical deoxidation cell was developed, to surpass this limitation caused by the over‐optential of the electrochemical cell and thus decreasing the oxygen concentration to sub‐ppm levels at the interface between the molten Fe and the solid electrolyte.

Effect of Applied Voltage on Electroreduction with Controlled Oxygen Flow of Molten Slag Containing FeO at 1723 K

“…In other applications, a dynamic mode of operation is employed and the close circuit current or voltage is measured as a function of time. Cells operating in this manner have been used in such applications as diffusion coefficient measurements [29][30][31][32][33] and electrolysis with COF which includes electrolytic refining of molten metal [34][35][36][37][38][39][40][41][42][43] and the above mentioned extraction of metal from molten salt systems. [9][10][11][12][13][14]44,45) However, little work has been done on extraction of metal from high-temperature molten oxide systems.…”

Influence of Basicity on Anodic Reaction in CaO-SiO2-Al2O3Melts

“…Electrochemical research on the anodic reaction of free oxygen ions has been continuously pursued to determine the potential of molten oxides as electrolytes in various electrochemical applications, namely, molten oxide electrolysis (MOE), [2][3][4][5][6][7][8][9][10][11][12] direct current electro-slag remelting (DC-ESR), 13 and electrorefining. [14][15][16][17] Since basicity as a measure of oxygen ions in molten oxides is a fundamental index for defining the equilibrium state of chemical reactions in molten oxides, extensive research has been carried out using basicity measurements to define the chemical potential of oxygen ions in molten oxides qualitatively. However, it is difficult to directly evaluate the activity of free oxygen ions because it is impossible to experimentally measure the chemical potential of ionic species in solution due to the constrain of electro-neutrality.…”

A New Design of Oxygen Sensor for Electromotive Force Measurement and Electrochemical Deoxidation by Using Oxygen Pump

“…Several researchers attempted to develop this technology by using similar apparatus mentioned above, i.e., an oxygen sensor with different metallic lead wire, such as chromel (Ni-Cr alloy), Mo, Pt and so on. [10][11][12][13][14][15][16][17] Nevertheless, there is no evidence on which we can avoid the oxidation of metallic lead wire at high temperature. The result of low oxygen concentration in molten metals might be caused by both electrochemical and chemical deoxidation in the previous works.…”