Study On The Process And Mechanism Of Cu-Zr Master Alloy Prepared By Molten Salt Electrolysis

Cu-Zr alloy in the aerospace,nuclear industry,electronic chip,transportation and other fields are widely used.At present,the distribution of copper-zirconium alloy of contents is uneven,and the operation of produce C u-Zr alloy is cumbersome and can not be continuously produced.In this paper,LiF-BaF₂-CaF₂-ZrO₂ was used as the molten salt system to prepare copper-zirconium alloy.The effect of different temperature and cathode current density on the cell voltage and current efficiency was studied.C u-Zr binary alloy was prepared.The Cu-Zr-Mg ternary alloy was prep ared by using LiF-BaF₂-CaF₂-ZrO₂-MgO as the molten salt system at 1233 K and pure copper rod as the consumable cathode.Electrochemical studies on the deposition mechanism of zirconium on the cathode: At the same time,the elec trode and the reference electrode were graphite and platinum wire under the conditions of electrochemical technology cyclic voltammetry,timing potential,time current method of molten salt system Zr4 + The electrochemical reduction mechanism of Zr4 + on the working electrode tungsten wire was studied under the condition that the electrode and the reference electrode were tungsten rod and platinum wire respectively.The copper and zirconium and zirconium magnesium alloys prepared in electrochemistry and process were analyzed by XRD and SEM.The composition and morphology of the alloys were obtained.The conclusions are as follows:The electrolyte system LiF-BaF₂-CaF₂ has good chemical thermal stability and fluidity at the temperature of 1373 K and 1233 K,and it retains good conductivity after adding zirconium oxide and magnesium oxide.At high temperature Molten salt density than the alloy density is small,the preparation of the alloy deposited in the bottom of the graphite crucible is covered with molte n salt is not easy to contact with air lead to burning.Liquid copper for the preparation of copper-zirconium alloy cathode process: 1373¹473K temperature electrolysis is feasible.The tank voltage decreases as the temperature in the furnace rises,and the tank voltage is proportional to the cathode current density.When the curre nt density is less than 1.29 A /cm2,the current efficiency increases from 62% to 66.5% with the increase of the current density at the current density of 1420 K and the current density is in the range of 1.0¹.5A /cm2.When the current density is greater than 1.29 A / cm2,the current efficiency decreases from 66.5% to 63% with increasing current density.At current density of 1.29 A /cm2,the current efficiency has a maximum value,a nd the current efficiency is the highest at 66.5%.At the temperature of 1233 K under the conditions of copper rod as the cathode,in the electrolyte LiF-BaF₂-CaF₂ by adding magnesium oxide and zirconium dioxide can be prepared copper zirconium and magnesium ternary alloy,the melting point of the alloy is lower than 1233 K,the alloy sinks in graphite the bottom of the crucible,the alloy in appearance and pure copper and no difference.The copper-zirconium-magnesium ternary alloy can be prepared by adding magnesium oxide and zirconium dioxide to the electrolyte LiF-BaF₂-CaF₂ with the copper rod as the consumable cathode at the temperature of 1233 K.In the 20% LiF-22% CaF₂-58% BaF₂ electrolyte system,ZrO₂ with a mass fraction of（0.5-0.9 %）was added to the electrode,and the zirconium ion was added to the tungsten electrode The process of reduction to metal zirconium is two-step reduction,that is,Zr⁴⁺ + 2e → Zr2+,Zr2+ + 2e → Zr,the reaction process is quasi-reversible reaction.At different scanning rates,the reduction peak current of zirconium ion and the square root of the scanning rate showed a good linear relationship,indicating that the reduction process of Zr⁴⁺ was controlled by the diffusion step.The precipitation potentials were-0.87 V and-1.07 V,respectively,and the zirconium ions were reduced to two-step reduction in the system.The reduction process of the zirconium ions on the tungsten electrode is calculated as two steps,and two electrons are respectively obtained.The ion diffusion coefficient was 6.7 × 10-6cm2/s by the Cottrell equation using the chronoamperometry.The nucleation mechanism of precipitation of zirconium on tungsten electrode is transient nucleation.The counter electrode of the three-electrode system is tungsten rod.In the 20% LiF-22% CaF₂-58% BaF₂-ZrO₂ electrolyte system,the reduction process of zirconium is a two-step reduction process.The reduction process takes two electrons at each step.