氯化物熔体中铈离子在铁阴极上的电还原

ELECTROCHEMICAL REDUCTION OF Ce(Ⅲ) ON Fe ELECTRODE IN MOLTEN CHLORIDES

用循环伏安法、充电曲线和衰减曲线研究了在700～850°CNaCl-KCl-CeCl_3熔体中铈离子在铁电极上的还原过程。Ce(Ⅲ)还原时,首先形成金属间化合物,然后析出纯金属铈。用铁阴极电解制取了含83wt％Ce的Ce-Fe合金,其物相为CeFe_2和Ce。

The RE-Fe-B system has received much attention because the Nd-Fe-B permanent magnet is shown to possess the highest known energy product. Cerium or lanthanum are cheaper than neodymium. It is interested to use Ce or La instead of Nd. We have investigated the electrodeposition of Ce-Fe alloy in order to supply the raw material for the preparation of Ce-Fe-B magnet.The cyclic voltammetry, charge curve and decay curve were used to study the electrode process of Ce(Ⅲ) reduced on iron electrode in molten NaCl-KCl-CeCl_3 from 700℃ to 850℃. The first reduction peak and the second wave start at -2.75V and -3.02V (700℃) respectively. The plateaus potentials on the charge curve are in concordance with the corresponding starting wave potentials of the voltammogram. The plot of E versus log((I_p-I)/I) is linear. Then value of three was calculated from the slope. The Ce-Fe alloy rich in Ce can be obtained by electrolysis with iron electrode in molten NaCl-KCl-CeCl_3. The Ce-Fe alloy is composed of CeFe_2 and Ce determined by X-ray diffraction. Based on the results, we can consider that the metallic compound CeFe_2 is formed first, and then the metallic Ce deposits when Ce(Ⅲ) is reduced on iron electrode.