关键词: 熔盐, 镁, 阴极放电, 钝化

Abstract: The discharge process and passivation behaviors of Mg(Ⅱ) on cathode(Mo、W) in MgCl2-KCl-NaCl-CaCl2 molten salt system had been investigated by means of cyclic voltammetry and chronoamperometry.The composition of molten salt was MgCl(10%)+CaCl(20%)+NaCl(60%)+KCl(10%)(by mass) and the temperature of electrolysis was 725 ℃.The deposition potential of Mo was 37 mV more negative than that of W,while the peak current was sharper than Mo according to the voltammograms at 0.05 V/s,indicating that the passivation on Mo cathode is easier than W.The formation of MgO impurities during the electrolysis could cause the cathode passiration.However,the reversibility on the discharge reaction of W cathode was better than Mo electrode,and the reduction peak potential of W electrode almost unchanged with the scan rate.The I～t-1/2 curves demonstrated a positive linear relationship on W electrode,but deviated from the linear characteristics on Mo electrode due to the passivation.

Key words: molten salt, magnesium, cathode discharge, passivation