Study On Preparation Of Al-Li Alloy By Electro-deoxidation From Molten Salts

The traditional industry producing of Al-Li alloy is ingot metallurgy which is often complicated by problems of demanding expensive equipments and high purity metals due to inhomogeneous composition,and expensive cost.Recently,the electro-deoxidation has received much attention due to their cheaper price,easier operation,and more friendly environment.It is a process that oxides are directly divided into metals and oxygen.All these advantages have allowed the electro-deoxidation to be an ideal method for Al-Li production.In this paper,the mechanism of electro-deoxidation process was investigated in different electrolytes.The Al-Li alloy can't be obtained from CaC12-LiCl molten salts.That's because the Li2O will react with CaC12 producing LiCl and CaO.Then the CaO will further react with aluminum ions and oxygen ions forming the Ca12A114O33 phase,which hinders the deoxidization reaction.Therefore,the CaC12 molten salt isn't suitable for producing Al-Li alloy by the electro-deoxidation process.The Al-Li alloy was successfully produced from LiF-LiCl molten salts containing Li2O with aluminum as the cathode.The Li content in the Al-Li alloy can be reached to 2wt.%and the yield of alloy is about 30%.The Li content in the Al-Li alloy will increase with increasing electrolysis time.The lithium element exists in the alloy exists in the form of Al7CuLi4,and Al2CuLi.The SEM images show that the alloy deposits are uniform with network-like structure.However,the results show that the pulverization of precursor is harmful for improving the Li content in the Al-Li alloy.The Al-Li alloy also can be produced from KCl-LiCl molten salts.The cyclic voltammetry experiments show that the reduction onset potential of Al-Li alloy which was produced from Li2O,Al,and Cu by electro-deoxidation process is-1.OV(vs.Ag/AgCl).It is more positive than the reduction onset potential(about-2.2V(vs.Ag/AgCl))of Li+.The electrolysis experiment results show that the content of Li in alloy and the yield of alloy increase' with increasing electrolysisi time,applied potential,appropriate temperature and Cu powers.The maximum Li content in the Al-Li alloy and the yield can reach as high as 8.97%and 76%,respectively.The XRD analyses confirm that the lithium element presents as A12CuLi,Al5.1CuLi3,A16CuLi3,and LiAl phase in the obtained alloy.The SEM analyses reveal that the alloy phases prepared by the electro-deoxidation process distribute uniformly.Among the three candidate molten salts,the KCl-LiCl molten salts are the most suitable electrolyte for producing Al-Li alloy by using electro-deoxidation process.