Electrochemical mechanism of electrolysis codeposition of Mg-Sr alloy in mol ten salt
(National Engineering Research Center for Integrated Utilization of Salt Lake Resources,
Key Laboratory of Safety Science of Pressurized System, Ministry of Education,
East China Uni versity of Science and Technology, Shanghai 200237, China)
Key Laboratory of Safety Science of Pressurized System, Ministry of Education,
East China Uni versity of Science and Technology, Shanghai 200237, China)
Abstract: The electrochemical process of Mg-Sr codeposition was studied in MgCl2-SrCl2-KCl melts containing different MgCl2 concentrations at 700 °C by cyclic voltammetry, chronopotentiometry and chronoamperometry. The results show that the actual precipitation potential of Sr reduces by nearly 0.5 V because of the depolarization effects of Sr activity reduced by forming Mg-Sr alloy. The codeposition potential condition of Mg and Sr to form Mg-Sr alloy is as follows: When electrode potential is more negative than -1.5 V, the magnesium will precipitate; when elec trode potential is more negative than -2.0 V, the magnesium and strontium will both deposit. The con trol step of codeposition process of Mg and Sr is not diffusion control step. The codeposition cur rent condition of Mg and Sr to form Mg-Sr alloy by chronoptentiometry is as follows: cathode current densities are higher than 0.71, 1.57 and 2.83 A/cm2 in MgCl2-SrCl2-KCl melts with MgCl2 concentrations of 2%, 5% and 10% (mass fraction), respectively.
Key words: molten salt electrolysis; Mg-Sr alloy; electrochemical reduction