Xindong Wang, Shuzhen Duan, E. Christensen, N. J. Bjerrum, and Y. Ito, Electrochemical Reaction Processes of Niobium Ions in FLINAK melt, J. Univ. Sci. Technol. Beijing, 6(1999), No. 2, pp. 83-89.
Cite this article as:
Xindong Wang, Shuzhen Duan, E. Christensen, N. J. Bjerrum, and Y. Ito, Electrochemical Reaction Processes of Niobium Ions in FLINAK melt, J. Univ. Sci. Technol. Beijing, 6(1999), No. 2, pp. 83-89.
Xindong Wang, Shuzhen Duan, E. Christensen, N. J. Bjerrum, and Y. Ito, Electrochemical Reaction Processes of Niobium Ions in FLINAK melt, J. Univ. Sci. Technol. Beijing, 6(1999), No. 2, pp. 83-89.
Citation:
Xindong Wang, Shuzhen Duan, E. Christensen, N. J. Bjerrum, and Y. Ito, Electrochemical Reaction Processes of Niobium Ions in FLINAK melt, J. Univ. Sci. Technol. Beijing, 6(1999), No. 2, pp. 83-89.
Metallurgy School, University of Science and Technology Beijing, Beijing 100083, China
Materials Science Group, Chemistry Department A, The Technical University of Denmark, DK-2800 Lyngby, Denmark
Department of Energy Science and Engineering, Kyoto University, Kyoto 606, Japan
中文摘要
To investigate the mechanism and influence of oxide and niobium metal on the electrodeposition of niobium, the electrochemical reaction mechanisms of niobium ions in LiF-NaF-KF eutectic (FLINAK) melt at 973 K was studied by chronopotentiometry, chronoamperometry and cyclic voltammetry. The electrochemical reduction process of Nb(V) (K2NbF7) in FLINAK melt relates to the complex anions. A two-step electrochemical reduction with disproportionate and catalytic reactions is proposed. The metallic niobium in K2NbF7-FLINAK melt can reduce the catalytic reaction. The influence of oxide (Na2O) on the electrochemical processes of Nb(V) in K2NbF7-FLINAK-O2- melts without and with niobium metal present was also studied. When oxide present in K2NbF7-FLINAK melt, a much stable oxyfluorocomplex ion is formed. Cyclic voltammetry showed that the reduction potential of oxyfluoro-complex ion is more negative than that of fluorocomplex ion (NbF62-). The electrochemical stability of NbOF63- is higher than those of NbF72- and NbF62-. An optimum composition for a coherent niobium metal coating on low-carbon steel is found to be 2.7%K2NbF7-0.5～2.0%Na2O-FLINAK in molar fraction. The cathodic current density is about 90 mA/cm2.
To investigate the mechanism and influence of oxide and niobium metal on the electrodeposition of niobium, the electrochemical reaction mechanisms of niobium ions in LiF-NaF-KF eutectic (FLINAK) melt at 973 K was studied by chronopotentiometry, chronoamperometry and cyclic voltammetry. The electrochemical reduction process of Nb(V) (K2NbF7) in FLINAK melt relates to the complex anions. A two-step electrochemical reduction with disproportionate and catalytic reactions is proposed. The metallic niobium in K2NbF7-FLINAK melt can reduce the catalytic reaction. The influence of oxide (Na2O) on the electrochemical processes of Nb(V) in K2NbF7-FLINAK-O2- melts without and with niobium metal present was also studied. When oxide present in K2NbF7-FLINAK melt, a much stable oxyfluorocomplex ion is formed. Cyclic voltammetry showed that the reduction potential of oxyfluoro-complex ion is more negative than that of fluorocomplex ion (NbF62-). The electrochemical stability of NbOF63- is higher than those of NbF72- and NbF62-. An optimum composition for a coherent niobium metal coating on low-carbon steel is found to be 2.7%K2NbF7-0.5～2.0%Na2O-FLINAK in molar fraction. The cathodic current density is about 90 mA/cm2.
下载: