Study On The Equilibrium Potential Law Of Co-Deposition Of Aluminum And Lanthanide、Alkaline Earth And Transition Elements In Molten Salt System

Aluminum alloy materials are widely used in aerospace,packaging production,automobile and shipbuilding and other fields due to their excellent performance.In this paper,aluminum alloy was prepared by molten salt electrolysis method.The electrochemical behavior of co-deposition of aluminium with lanthanide ions,alkaline earth and transition ions was studied.The equilibrium potential of aluminum-rich alloy was determined by open-circuit chronopotentiometry,and some regular results were found.In the 873K LiCl–KCl–LnCl₃（2 wt.%）–AlCl₃（2 wt.%）molten salt system,molybdenum wire is used as the working electrode,since Al³⁺will deposit elemental aluminum on the molybdenum wire first,which is equivalent to forming an"aluminium electrode".The electrochemical reduction mechanism of fourteen lanthanide elements（except promethium）was studied by cyclic voltammetry,square wave voltammetry and open circuit chronopotentiometry.The process of electrochemical reduction and its reversibility were summarized.It is concluded that the equilibrium potential of the Al-Lns alloy formed by lanthanide ions on the Al cathode shows a"Bimodel Effect".At the same time,the intrinsic reason of the“Bimodel Effect”of the equilibrium potential of the Al-Lns alloy is explained.The relationship between the equilibrium potential and the atomic radius of the lanthanide element is summarized and the mathematical equation is established.Cyclic voltammetry,square wave voltammetry,open circuit chronopotentiometry,chronopotentiometry and chronoamperometry were used to investigate and analyze the electrochemical behavior of Co²⁺,Ni²⁺and Mg²⁺and co-deposition with Al³⁺to form alloys.The relevant electrochemical parameters were calculated.Taking the analysis process of Al-Co,Al-Ni and Al-Mg alloys as typical examples,the electrochemical behavior of co-deposition of other typical transition and earth elements(Cu²⁺,Ti⁴⁺,Zr⁴⁺,Fe³⁺,Sr²⁺,Ba²⁺,Ca²⁺)and Al³⁺in LiCl-KCl molten salt system was analyzed to determine the equilibrium potential of their Al-rich alloys.XRD was used to analyze the phase of the above-mentioned Al transition alloy and alumina-alkaline earth alloy,and the morphology and composition of the alloys were determined by SEM and EDS.The equilibrium potential of the alloy formed by the transition element,alkaline earth metal and aluminum is found to be inversely proportional to the radius of the metal,that is,the larger the radius,the more negative the equilibrium potential,indicating the higher energy required to form the alloy for the larger metal atomic radius.According to this law,we derive the mathematical equation of equilibrium potential and metal atom radius.