Mechanism Study Of Preparing SmFe Alloy By Molten Salt Electrolysis

The electrochemical behavior of Sm(III) on inner Mo electrode and active Fe Electrode in LiF-CaF2-SmF3molten salts system was studied by electrochemical testing methods, the feasibility of SmFe alloy preparation by molten salts electrolysis was judged according to the cathodic process of Sm(III) on Fe electrode. The dissolution behavior of Sm in LiF-CaF2-SmF3system was investigated, clearing about the loss of metal Sm in fluoride system. The influence of temperature, current density and concentration of SmF3on electrolysis technology indexes such as current efficiency, Sm content and alloy generation rate were inspected, and SmFe alloys were preparedby electrolysis.The first part of this paper was the reduction process of Sm(â…¢) ions in fluoride molten salts. Sm(â…¢) can only be reduced to Sm(â…¡)via single electron transfer process in LiF-CaF2-SmF3system, and the course of Sm(â…¡) reduction to Sm(0) has not been observed. The reduction potential of Sm(III) to Sm(â…¡) was about-1.58V (vs. Pt) in the fluoride melts on Mo electrode at1173K, from the testing of cyclic voltammetry(CV) method. While the potential measured by square wave voltammetry (SWV)(about-1.51V) was close to this value. The reversibility of Sm(â…¢)/Sm(â…¡) was also studied via CV test in LiF-CaF2-SmF3system on Mo electrode at1173K, which indicating that the Sm(â…¢)/Sm(â…¡) was reversible under the scan rate of0.25V·s-1. Using the square wave voltammogram gave a total number of electrons involved in the electrochemical system equals to1.0, which indicates that the reduction of Sm(â…¢)/Sm(â…¡) is one electron transfer process. The diffusion coefficient (Dsm(â…¢)) of Sm(â…¢) in the condition mentioned above was calculated to be2.71×10-5cm2·s-1.The second part of this paper was the investigation of the electrochemical behavior of Sm(â…¢) on active Fe electrode by CV, SWV, and open-circuit chronopotentiometry (OCP) methods. The results showed that the signal of SmFe alloy formation could be observed. That was due to the intermetallic conpound could be formed by the under potential deposition (UPD) of Sm(â…¢) on Fe active electrode, which judged the feasibility of preparing SmFe alloy by electrolysis.The dissolution behavior of metal Sm in fluoride melts was also studied. The disproportionated reaction of Sm+2Sm(â…¢)â†'3Sm(â…¡) was identified from the dissolution of metal Sm in LiF-CaF2-SmF3system.From the experimental observation, the influence of temperature, current density and concentration of SmF3on electrolysis technology indexes such as current efficiency, Sm content and alloy generation rate were inspected at the last of this paper.The mechanism of SmFe alloy formation and influences of electrolysis effect on factors in electrolysis process had been further explored in this paper, providing reliable theoretical clues and technology method.