Molten Salt Electrodeposition of Praseodymium-iron Alloy

The electrochemical behaviour of Pr(III) on iron electrode in molten PrCl3-KCl-NaCl was studied by means of cyclic voltammetry and potential-time curve method. The results show that the reduction of Pr(III) to Pr on the iron electrode proceeds reversibly in one step and forms Pr-Fe alloys. The Pr-Fe alloys are obtained by molten salt electrolysis with molten KCl-NaCl as electrolyte and PrCl3 as raw materials. The composition of electrolytic product is PrFe2 and Pr analysed by X-ray diffraction. Pr recovery efficiency is 90% and the current efficiency is 85%.

Non-contact gaseous microplasma electrode as anode for electrodeposition of metal and metal alloy in molten salt

Microplasma based on glow discharge could act as a non-contact gaseous electrode and has attracted much attention in both fundamental research and application. Herein, with microplasma as the anode,the electrodeposition process of a series of metal and metal alloys in molten salt has been systemically studied. Four metal cations with different valence states, silver(Ag~+), nickel(Ni^(2+)), copper(Cu^(2+)), and iron(Fe^(3+)), could all be reduced on the solid cathode with high current efficiency and the corresponding metal products were of high purity. The electrodeposition of aluminum-lanthanum(Al-Ln) alloy on the aluminum cathode was also successfully carried out with microplasma as the anode, and the same alloy was obtained by using the conventional anode electrode. These results indicated that microplasma anode based on non-contact direct-current(DC) glow discharge is a promising electrode to be applied in molten salt electrolysis.

Measurement on Physicochemical Properties ofNaCl-KCl-ScCl_3 System for Manufacture of Al-Sc Alloy by Molten Salt Electrolysis

The physicochemical properties of the system, such as density, surface tension, specific conductance and melting point were measured. The results were discussed.

CO-DEPOSITION OF Li(Ⅰ)WITH RE(Ⅲ)AND ITS APPLICATION IN THE PRODUCTION OF Al-Li-Cu-RE ALLOY BY MOLTEN SALT ELECTROLYSIS

The possibility of co-deposition of Li(Ⅰ)and RE(Ⅲ)has been estimated by both theoretical analysis and experimental study on the influences of temperature and concen- tration of chloride on the deposition potential.Both the electrochemical and electrolytic results clearly show that Li(Ⅰ)and RE(Ⅲ)can co-deposit on the Al-Cu electrode under selected conditions.

Preparation of Mg-Li-Sm alloys by electrocodeposition in molten salt

Electrocodeposition of Mg-Li-Sm alloys was investigated in molten KCl-LiCl-MgCl2-SmCl3-KF system.The effects of electrolytic temperature and cathodic current density on current efficiency were studied and optimal electrolysis parameters were obtained.The optimum electrolysis condition was a molten salt mixture of LiCl:KCl =50:50(wt.%),electrolytic temperature:660 oC,cathode current density:9.5 A/cm2 and electrolysis time of 40 min.The current efficiency reached 77.3%.X-ray diffraction(XRD) and scanning elec...

Electrical conductivity optimization of the Na3AlF6–Al2O3–Sm2O3 molten salts system for Al–Sm intermediate binary alloy production

Metal Sm has been widely used in making Al–Sm magnet alloy materials. Conventional distillation technology to produce Sm has the disadvantages of low productivity, high costs, and pollution generation. The objective of this study was to develop a molten salt electrolyte system to produce Al–Sm alloy directly, with focus on the electrical conductivity and optimal operating conditions to minimize the energy consumption. The continuously varying cell constant(CVCC) technique was used to measure the conductivity for the Na3AlF6–AlF3–LiF–MgF2–Al2O3–Sm2O3electrolysis medium in the temperature range from 905 to 1055°C. The temperature(t) and the addition of Al2O3(W(Al2O3)), Sm2O3(W(Sm2O3)), and a combination of Al2O3and Sm2O3into the basic fluoride system were examined with respect to their effects on the conductivity(κ) and activation energy. The experimental results showed that the molten electrolyte conductivity increases with increasing temperature(t) and decreases with the addition of Al2O3or Sm2O3or both. We concluded that the optimal operation conditions for Al–Sm intermediate alloy production in the Na3AlF6–AlF3–LiF–MgF2–Al2O3–Sm2O3system are W(Al2O3) + W(Sm2O3) = 3wt%, W(Al2O3):W(Sm2O3) = 7:3, and a temperature of 965 to 995°C, which results in satisfactory conductivity, low fluoride evaporation losses, and low energy consumption.

Effects of additive NaI on electrodeposition of Al coatings in AlCl_(3)-NaCl-KCl molten salts

Effects of NaI as an additive on electrodeposition of Al coatings in AlCl_(3)-NaCl-KCl(80-10-10 wt-%)molten salts electrolyte at 150°C were investigated by means of cyclic voltammetry,chronopotentiometry,scanning electron microscopy and X-ray diffraction(XRD).Results reveal that addition of NaI in the electrolyte intensifies cathodic polarization,inhibits growth of Al deposits and increases number density of charged particles.The electrodeposition of Al coatings in the AlCl_(3)-NaCl-KCl molten salts electrolyte proceeds via three-dimensional instantaneous nucleation which however exhibits irrelevance with NaI.Galvanostatic deposition results indicate that NaI could facilitate the formation of uniform Al deposits.A compact coating consisting of Al deposits with an average particle size of 3μm was obtained at a current density of 50 mA∙cm^(−2) in AlCl_(3)-NaCl-KCl molten salts electrolyte with 10 wt-%NaI.XRD analysis confirmed that NaI could contribute to the formation of Al coating with a preferred crystallographic orientation along(220)plane.

Electrodeposition of magnesium-yttrium alloys by molten salt electrolysis

Electrodeposition of magnesium-yttrium alloys from molten salts was studied by electrochemical techniques.LiF-YF3 was electrolyte system with magnesium oxide and Yttrium oxide as raw materials.It was proved that Mg2+ and Y3+was deposited more prior than other ions during cyclic voltammetry and potential step measurement at 1050 °C.Voltammograms showed Mg2+ could be deposited at-0.5 V,and Y3+ could be deposited at-0.7 V on tungsten electrode compared with platinum electrode.The sedimentation of Mg2+ was more positive about 230 mV than that of other ions in electrolyte.The electrolytic codeposition of yttrium and magnesium was 0.58 V on condition that the weight ratio of Y2O3/MgO was 4:1.Chronopotentiogram indicated that the process of electrodeposition of magnesium-yttrium alloys on tungsten electrode was controlled by diffusion of ions from electrolyte to electrode interface.It was feasible to prepare Magnesium-Yttrium alloys by controlling content of ions in molten salt electrolyte.

Preparation and properties of Al-Mn alloy coatings in NaCl-KCl-AlCl_3-CeCl_3 molten salts

Al-Mn alloy coatings were electrodeposited on an iron substrate from AlCl3-NaCl-KCl molten salts with anhydrous MnCl2 enhanced by the addition of CeCl3. The microstructure and properties of the Al-Mn alloy coatings were investigated, and scanning electron microscopy, X-ray diffraction, and polarization curves were used to determine the composition, surface morphology, phase structure, and corrosion resistance of the obtained deposits. The results showed that the surface coatings were smooth, and that the crystallites were dense and uniform when 0.22 wt.% CeCl3 was added to the molten salt. An amorphous mixture of Al and Al6Mn was obtained. CeCl3 enhanced the corrosion resistance and increased the hardness of the single amorphous phase alloys. The pitting potential of the coating was approximately -1.1239 V, and its hardness was 390 kgf/mm2.

Cathodic reduction process of Al-Cu-Y alloy in fluoride-oxide eutectic system via molten salt electrolysis

Al-Cu-Y alloys were prepared by molten salt electrolysis in fluoride-oxide system composed of electrolyte（Na3 AlF6-AlF3-LiF-MgF2） and oxide（Al2 O3-CuO-Y2 O3）. Cathodic reduction process of Al2 O3,CuO and Y2 O3 were analyzed by cyclic voltammetry and chronoamperometry. Components and phase composition of alloy samples prepared by potentiostatic electrolysis were characterized by scanning electron microscopy and energy dispersive spectroscopy. The results show that the Al-Cu-Y alloy can be prepared in the AIF3-NaF-5 wt%LiF-5 wt%MgF2（NaF/AlF3 = 2.2, molecular ratio） eutectic system with mixed oxide（Al2 O3-CuO-Y2 O3） through 2 h at the conditions of a temperature of 1208 K, cell voltage3.0 V, cathode current density 0.7 A/cm^2. Al（Ⅲ） and Cu（Ⅱ） ions can be reduced to zero valence Al（0） and Cu（0） directly on carbonaceous electrode surface by instantaneous nucleation, respectively, the reduction process is controlled by diffusion. The reduction potential of Y（Ⅲ） ions is close to the active ions of fluoride melts, but strengthened phase AI3 Y can be formed through electrochemical reduction and alloyed process with active Al（Ⅲ） and Cu（Ⅱ） ions, meanwhile, the Al2 Cu and Al3 Y phases are distributed at the grain boundary of Al matrix.

Density of Na3AIF6-AIF3-LiF-MgF2-Al2O3-Sm2O3 molten salt melt for Al-Sm alloy

Samarium（Sm） has been widely used in making aluminum（Al）-Sm magnet alloy materials. The research team for this study developed a molten salt electrolyte system which directly produces AI-Sm alloy to replace the energy intensive conventional distillation technology. In this study, molten melt density was measured and operation conditions were optimized to separate AI-Sm alloy product from the fluoride molten melt electrolysis media based on density differences, Archimedes＇ principle was applied to measure density for the basic molten fluoride system（BMFS： Na_3 AlF_6-AlF_3-LiF-MgF_2）electrolysis media in the temperature range from 905 to 1055 ℃.The impact of temperature（t） and the Al_2O_3 and Sm_2O_3 addition ratio（w_（（Al2O3））,w_（（Sm2O3）） in the basic fluoride system on molten melt density was examined. The fluoride molten melt density relationship was determined to be：ρ=3.11701-0.00802 w_（（Al2O3））＋0.027825 w_（（Sm2O3））-0.00117 t. The test results showed that molten density decreases with increase in temperature and Al_2O_3 addition ratio, and increases with the addition of Sm_2O_3, and/or Al_2O_3＋Sm_2O_3. The separation of Al-Sm（density 2.3 g/cm^3） product melt from the BMFS melt is achieved by controlling the BMFS density to less than 2.0 g/cm3. It is concluded that the optimal operation conditions to control the BMFS molten salt density to less than 2.0 g/cm^3 are：maintain addition of Al_2O_3＋Sm_2 O_3（w_（（Al2O3））＋w_（（Sm2O3））〈9% of Na_3AlF_6,Al_2O_3/Sm_2O_3 ratio（w_（（Al2O3））：w_（（Sm2O3）））〉 7：3, and temperature between 965 and 995 ℃.

Preparing different phases of Mg-Li-Sm alloys by molten salt electrolysis in LiCl-KCl-MgCl_2-SmCl_3 melts

Different phases of Mg-Li-Sm alloys were prepared by galvanostatic electrolysis in LiCl-KCl-MgCl2-SmCl3 melts at 670 °C.The electrolysis process and phase control of Mg-Li-Sm alloys were studied.The microstructures of α,α+β,β phases of Mg-Li-Sm alloys were characterized by X-ray diffraction(XRD) and optical microscope(OM).Analysis of scanning electron microscopy(SEM) and EDS mapping analysis showed that Mg distributed homogeneously in Mg-Li-Sm alloys.EDS result showed that the distribution of Sm was more at...

PREPARATION OF Al-Sc ALLOY IN CHLORIDE SYSTEM WITH MOLTEN SALT ELECTROLYSIS

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New preparation of Mg-Li-Al alloys by electrolysis in molten salt

This work presents a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode （Mo electrode） in a molten KCl-LiCl-AlC13-MgCI2-KF system. It aims at preparation Mg-Li-Al metal alloy directly under an optimal electrolytic parameters. Main factors which affect current efficiency are investigated. We have discussed the co-electrodeposition conditions and the effect of technical parameters on these experiments, and gained a good electrolytic process. The result of calculation shows that co-electrodeposition Mg, Li and A1 occurs at the cathode current density higher than 9 A/cm^2 and electrolytic voltage between 6 to 9 V. And at the optimal parameters, 12-13 A/cm^2, 620-640 ℃, the highest current efficiency reaches as high as 86%. Lithium combined with magnesium forms Li0.92Mg4.0s and LiaMg7, and aluminum mainly exists in a form of Mg0.58Al0.42, distributing in the alpha phases and beta phases.

Study on electrochemical preparation of Al-Li-Y alloys from Y_2O_3 in LiCl-KCl-AlCl_3 molten salts

The electrochemical preparaton of Al-Li-Y alloys from LiCl-KCl-AlCl3-Y2O3 system was studied. The chlorination of Y2O3 by AlCl3 led to the formation of Y （III） ions in the molten salts. Cyclic voltammogram （CV） showed that the underpotential deposition （UPD） of yttrium on pre-deposited aluminum caused the formation of Al-Y alloy. Al-Li-Y alloys with different yttrium contents were obtained by galvanostatic electrolysis and analysed by SEM-EDS and ICP. The ICP results showed that the lithium and yttrium contents in Al-Li-Y alloys depended on the addition of AlCl3 into the melts.

Al-Mn合金镀层的研究

在 2 0 0℃共融的氯化物熔盐中 ,以MnCl2 作为添加剂 ,电沉积出Mn含量为 1 8%～ 40 %的Al Mn合金镀层 .结果表明 ,当合金镀层中Mn含量超过 31 %时 ,具有单一的非晶态镀层 ,单相非晶态镀层的耐蚀性、硬度等性能均优于双相镀层 .Ti和Ce的加入 ,促进了Al Mn金属玻璃的形成 ,使Mn含量较低的单相非晶体Al Mn合金电沉积成为可能 ,提高了Al Mn合金镀层的耐蚀性和硬度 ,使其点蚀电位提高了 2 0 0mV ,镀层硬度提高到 80 0Hv .

Al-Mn-Ce(Ti)合金镀层的研究

在酸性氯化物熔盐体系中，应用循环伏安法研究了 Ｔｉ， Ｃｅ 对 Ａｌ Ｍｎ 合金镀层沉积过程的影响，使铝的沉积电位向正方向移动·运用 Ｘ 射线衍射、电化学测试仪和显微硬度计等实验手段，测试了 Ｔｉ 和 Ｃｅ 对 Ａｌ Ｍｎ 合金镀层结构、耐蚀性和硬度的影响·结果表明， Ｔｉ 和 Ｃｅ 的加入，促进了 Ａｌ Ｍｎ 金属玻璃的形成，使含 Ｍｎ 量较低的单相非晶体 Ａｌ Ｍｎ 合金电沉积成为可能·提高了 Ａｌ Ｍｎ 镀层的耐蚀性和硬度，使其点蚀电位提高了１００ ～２００ ｍ ｖ ，镀层硬度提高到８００ Ｈｖ·

Al-Mn合金镀层的微观结构及耐蚀性

在AlCl3-NaCl-KCl低温共融盐中，添加无水MnCl2，接通直流电在铁片上获得Al—Mn合金镀层。用扫描电镜、能量色散谱、X射线衍射和极化曲线对分别对该合金镀层的形貌、组成、相结构及耐腐蚀性能进行测试。结果表明：纯铝镀层表面呈针状，锰质量分数9．20％的镀层表面呈花状，锰质量分数25．43％的镀层表面有无规则瘤节状凸起物且晶界模糊，而锰质量分数达到34．42％时，晶粒细化，晶界清晰；合金镀层中锰质量分数与熔盐中无水MnCl2的质量分数呈线性关系；锰质量分数为20．84％～29．74％的镀层为单一的非晶态结构，锰质量分数高于29．74％的镀层为Al8Mn5晶体与非晶态的双相结构；合金镀层的点蚀电压比纯铝镀层高180～360mV，单相非晶态合金镀层的耐蚀性优于双相镀层。

双脉冲镀对低温熔融盐镀Al-Mn合金层的影响

以铁片为基体,分别采用直流和双脉冲电源,在AlCl3-NaCl-KCl-MnCl2低温熔融盐中获得了Al-Mn合金镀层.用SEM、金相、EDS和XRD研究了Al-Mn合金镀层表面形貌、沉积速度、组成结构及耐腐蚀性能.结果表明,双脉冲镀层更致密,表面更平整,但沉积比直流镀慢;在MnCl2含量相同的条件下,双脉冲镀层中Mn含量更高;合金镀层结构随镀层中Mn含量的增加,经铝固熔体与非晶相混合、单一非晶态、非晶相与晶态Al8Mn5混合三个阶段;单一非晶态镀层耐蚀性比双相镀层好,Mn含量相当的双脉冲镀层耐蚀性比直流镀层好.

Al-Mn非晶合金镀层

研究了在普通钢板上熔盐电解沉积ＡｌＭｎ非晶合金，通过实验确定了电解ＡｌＭｎ非晶合金的熔盐电解液，讨论了电流密度、电镀温度等参数对电流效率及ＡｌＭｎ非晶合金镀层的成分、结构、耐蚀性的影响。结果表明，当电流密度为２０～２５ｍＡ／ｃｍ２、镀液的ＭｎＣｌ２量在１．５％～３．５％、电解温度为１８０～２５０℃时。