Study On Separation Of Gd、Eu And Preparation Of Al-Gd-Sm、Mg-Li Based Alloys By Electrolysis In Molten Salt

The separation of the rare earth elements, especially similar rare earth element, is one ofthe most difficult problems in inorganic chemistry as the physical and chemical propertiesof rare earth elements are very similar. The existing basic methods of separation of rareearth elements contain solvent extraction, fractional crystallization, and ion exchangemethod etc. In this paper, the separation method of Gd, Eu directly by electrolyzingGd2O3-Eu2O3with molten salt electrolysis was investigated, and the influencing factors ofelectrochemical mechanism and the separation factor were studied.Al and Mg-Li based alloys are used widely in today’s light alloy, occupying a pivotalposition in many areas. The method of preparing doped lithium aluminum and magnesiumalloys in industry contains thermal reduction method and direct mixture method, In thispaper the molten salt electrolysis is used to prepare aluminum rare earth and magnesiumlithium-based alloys directly. And the electrochemical mechanism, alloy microstructure andthe electrolysis process were studied.There are four sections in this paper.1、The mechanism of the separation of Gd, Eu Directly from Gd2O3and Eu2O3wasinvestigated in the LiCl–KCl molten salt. The electrochemical codeposition of Gd, Eu wasstudied by solubility, cyclic voltammetry, and open circuit potential. The Gd and Eu wasseparated and prepared intermetallic compound by the method of molten salt electrolysis.In this paper, relationship of the electrolytic temperature, electrolysis time, current densitywith separation factor was investigated separately.2、The electrochemical behaviour of Sm (Ⅲ), Al (Ⅲ) and Gd (Ⅲ) ions wasinvestigated on tungsten in the NaCl–KCl molten salt in the temperature range720℃. Thediffusion coefficient of Sm (Ⅲ), Al (Ⅲ) and Gd (Ⅲ) ions in the melts was also determined.The mechanism of electrochamical co-deposition of Sm (Ⅲ), Al (Ⅲ) and Gd (Ⅲ) ions wasinvestigated, and Al-Gd-Sm alloys were prepared via galvanostatic electrolysis.3、Al-Gd-Sm alloys were prepared by electrochemical codeposition on a Mo electrodein the NaCl–KCl melts. In this paper, relationship of the material content, current densityand temperature with current efficiency was investigated separately.The electrolysis processparameters under galvanostatic electrolysis were investigated. The microstructure of alloysample was characterized by scanning electron microscopy (SEM). The effect of Gd, Sm on the microstructure and hardness of the alloys is also studied.4、The electrochemical behaviour of Gd (Ⅲ) on the copper, nickel and aluminumelectrodes respectively was studied in LiCl-KCl-GdCl3(1.5wt.%) molten salts at600℃.The results indicated the deposition potential value on activity electrodes was morepositive than the potential on inert electrodes. Gd (Ⅲ) appear underpotential deposition(referred to as UPD) behavior. The reduction of Zn (II) on the molybdenum electrode iscontrolled by diffusion of the electrode process, And Zn (II) diffusion coefficient is obtainedin molten salt, The condition of co–electrodeposition of Mg、Li、Zn、Gd was furtherinvestigated and the Mg-Li-Zn-Gd alloy was prepared by co-deposition.