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electrochemical formation of holmium-cobalt alloys

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Rare Metals 2003年第1期22卷 19-24页

作者： SUYuzhi YANGQiqin LIUGuankun DepartmentofChemistry SchoolofBiologicalandChemicalEngineeringGuangzhouUniversityGuangzhou510405China DepartmentofChemistry SchoolofChemistryandChemicalEngineeringZhongshanUniversityGuangzhou5102

The electrochemical formation processes of holmium-cobalt alloys on cobaltcathode in molten HoCl_3-KCl were investigated by cyclic voltammetry and open current potential-timecurve alter potentiostatic electrolysis. The structure of Ho-Co alloys' films deposited on cobaltelectrode by potentiostatic electrolysis was characterized by X-ray diffraction. The standard Gibbsfree energies of formation for the intermetallic compounds of Ho and Co were determined. Thediffusion coefficient and diffusion activation energy of Ho atom in the alloy phase were calculatedto be 10^(-10) -10^(-11) cm^2/s and 96.0 kJ/mol, respectively, from the current-time curve atpotential step.

关键词： rare earths holmium-cobalt alloy electrochemical formation moltenchloride Gibbs free energy of formation diffusion coefficient

A new electrochemical preparation method for formation Sm-Al alloys on inert Mo electrode from Sm_2O_3 in LiCl-KCl-MgCl_2 -KF molten salts

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Acta Metallurgica Sinica(English Letters) 2012年第2期25卷 102-110页

作者： Qiong CHEN Wei HAN Yusheng YANG Yanlu XU Key Laboratory of Superlight Materials and Surface Technology Ministry of Education College of Materials Science and Chemical Engineering Harbin Engineering University Harbin 150001 China China Nuclear Power Operation Technology Corporation LTD. Wuhan 430223 China

This work presents a new method for preparation of samarium alloy. Using A1 rod as anode, electrochemical formation of Sm-A1 alloy on Mo electrode from Sm203 in LiC1- KC1-MgC12-KF molten salts was investigated. Samarium mainly exists in the form of A12Sm in Li-Mg matrix, and the concentration of Sm in this alloy runs up to be as high as 34.7%. The reaction of samarium preparation appears like a replacement reaction. The new preparation method makes possible a high samarium content in electrochemical deposition of Sm-A1 alloy. Using A1 rod as anode consumedly decreased, the electrolytic cell voltage, and facilitated Sm deposition from Sm203. This preparation method uses 8m203 as raw materials to gain samarium alloy directly, which could revolutionize the industrial production of samarium alloys.

关键词： electrochemical formation Molten salt Sin-A1 alloy Inert electrode

Progress in preparation of rare earth metals and alloys by electrodeposition in molten salts

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Rare Metals 2016年第11期35卷 811-825页

作者： Wei Han Mei Li Mi-Lin Zhang Yong-De Yan Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering University

Rare earth（RE） metals and their alloys have attracted considerable practical interests due to their functional properties. Because of their negative deposition potentials, RE metals cannot be electrochemically deposited from aqueous media. Using molten salt as medium provides a unique opportunity for the electrowinning and electrorefining of high-purity RE metals, as well as for the electrochemical formation of their alloys and intermetallic compounds. Certainly, the electrochemical behaviors of RE metals and their alloys have been investigated in a number of different molten salts comprising all-fiuorides,all-chlorides and mixed chloride-fiuoride media. Based on the results, RE and their alloys were produced by molten salt electrolysis. In this paper, the developments of preparation of RE metals and their alloys by electrolysis in molten salts in recent years were systematically summarized on both the local and international levels. Attention was paid mainly to the electrodeposition of RE metals and their alloys, including RE-Mg, RE-Al, RE-Ni, RE-Co,RE-Cu, RE-Fe and RE-Zn alloys.

关键词： electrochemical formation Molten salts Electrolysis Rare earth Alloys

electrochemical behavior of Y(Ⅲ) and preparation of Y-Ni intermetallic compounds in molten LiCl-KCl salts

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Journal of Rare Earths 2017年第1期35卷 90-97页

作者： HAN Wei ZHAO Qiang WANG Ji LI Mei LIU Wenlai ZHANG Milin YANG Xiaoguang SUN Yang Key Laboratory of Superlight Materials and Surfbce Technology Ministry of Education College of Materials Science and Chemical Engineering Harbin Engi- neering University Harbin 150001 China

The work concerned the electrochemical behaviors of Y（Ⅲ） on W and Ni electrodes in molten LiCl-KCl salts by a series of electrochemical techniques. The electrochemical reaction of Y（Ⅲ） to Y（0） proceeded in a one-step reduction process with the exchange of three electrons, Y（Ⅲ）＋3e^–→Y（0）. Compared with the cyclic voltammogram and square wave voltammogram obtained on W electrode, the reduction potential of Y（Ⅲ） on Ni electrode was observed at less negative potential than the one of Y（Ⅲ） to give pure Y metal on W electrode, which revealed the occurrence of underpotential deposition of Y（Ⅲ） on Ni electrode. Electromotive force（emf） measurements were performed to calculate the relative partial molar Gibbs energies and activities of Y in Y-Ni alloys. The standard Gibbs energies of formation for different Y-Ni intermetallic compounds were also estimated. The different Y-Ni alloys were formed by potentiostatic electrolysis at different potentials and characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, and energy dispersive spectrometry（EDS）. It was found that four intermetallic compounds, YNi5, Y2Ni7, YNi3 and YNi2, were selectively produced by controlling applied potential.

关键词： electrochemical formation Y-Ni intermetallic compounds Ni electrode potentiostatic electrolysis thermodynamic properties rare earths

electrochemical co-reduction of holmium and magnesium ions in eutectic LiCl-KCl salts

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Rare Metals 2022年第4期41卷 1394-1402页

作者： Ji Wang Mei Li Wei Han Zhi-Yixiong Liu Xiao-Guang Yang Yang Sun Mi-Lin Zhang Key Laboratory of Superlight Materials and Surface Technology College of Material Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China Institute of Nuclear Energy and Safety Harbin Engineering UniversityHarbin 150001China

The electrochemical co-reduction of Ho(Ⅲ)and Mg(Ⅱ)ions was investigated on Mo electrode in eutectic LiCl–KCl salts at temperature of 773 K using various electrochemical *** voltammogram(CV)and square wave voltammogram exhibit three reduction peaks corresponding to the reduction of Ho(Ⅲ)on pre-deposited Mg electrode,whose potentials are more positive than that of Ho on Mo electrode because of the formation of Mg-Ho intermetallic compounds by co-reduction of Ho(Ⅲ)and Mg(Ⅱ)***,chronopotentiometry and open-circuit chronopotentiometry were used to explore the electrochemical formation of Mg–Ho ***–Ho alloys were produced by galvanostatic electrolysis at the current of 1.5 A for different electrolysis ***_(5)Mg_(24),HoMg_(2) and HoMg intermetallic compounds were acquired and characterized by X-ray diffraction(XRD)and scanning electron microscopy(SEM)coupled with energy-dispersive spectroscopy(EDS).The results indicate that Mg–Ho intermetallic compounds,Ho_(5)Mg_(24),HoMg_(2) and HoMg,could be prepared by molten salts electrolysis.

关键词： electrochemical formation Co-reduction MgHo alloys Galvanostatic electrolysis

electrochemical behavior of Dy(Ⅲ) on bismuth film electrode in eutectic LiCl-KCl melts

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Journal of Rare Earths 2018年第9期36卷 1007-1014页

作者： Shanshan Wang Baicong Wei Mei Li Wei Han Milin Zhang Xiaoguang Yang Yang Sun Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Material Science and Chemical EngineeringHarbin Engineering University

An electrochemical study of dysprosium（III） on Bi film electrode was carried out in eutectic LiCl-KCI melts by transient and steady state electrochemical *** results of transient electrochemical techniques showed that the reduction of Dy（III） appears at a more positive value than the one detected on W electrode owing to the formation of Bi-Dy intermetallic compounds through electrochemical deposition of Dy on bismuth film *** thermodynamic properties of the formation for Dy-Bi intermetallics were estimated by a steady state electrochemical method in a temperature range of 713-803 ***,the electrochemical preparation of Bi-Dy alloys was conducted by galvanostatic electrolysis at different current *** Bi-Dy alloys,characterized by scanning electron microscopy equipped with energy dispersive spectrometry and X-ray diffraction,are comprised of DyBi3/5 and DyBi phases

关键词： electrochemical behavior Bi film electrode Bi-Dy alloy Molten chlorides electrochemical formation Rare earths

Fluorination reaction of UO_(3)and electrochemical preparation of UO_(2)

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Chinese Chemical Letters 2022年第7期33卷 3435-3438页

作者： Rugeng Liu Yangyang Meng Wenjing Ji Wei Han Mei Li Yang Sun Key Laboratory of Superlight Materials and Surface Technology Ministry of EducationCollege of Material Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China

In this work,a technique was proposed to prepare UO_(2)from UO_(3)by the two processes of fluorination reaction of UO_(3)with NH_(4)HF_(2)and electrochemical reduction of UO_(2)^(2+)for the recycle *** feasibility of fluorination reaction was firstly confirmed using thermodynamic calculation;then,the products were analyzed using XRD,Raman and fluorescence to be UO_(2)F_(2).The fluorination mechanism was inferred to be UO_(3)(s)+NH_(4)HF_(2)→(NH_(4))_(3)UO_(2)F_(5)→NH_(4)(UO_(2))_(2)F_(5)→UO_(2)F_(2).The redox behavior of UO_(2)^(2+)on W electrode was investigated by cyclic voltammetry and square wave voltammetry,which indicated that UO_(2)^(2+) was reduced to UO_(2)via a two-step single electron transfer with *** diffusion coefficient of UO_(2)^(2+) was calculated to be 6.22×10^(-5)cm/*** disproportionation reaction of UO_(2)^(+) was observed,and the relationship between the disproportionation reaction and scan rate was ***,the electrochemical fabrication of UO_(2) was conducted by electrolysis at-0.8 V,and the product was analyzed by XRD,SEM and EDS to be UO_(2).ICP-AES results showed that the extraction efficiency of UO_(2) could reach 98.53%.

关键词： UO_(3) Fluorination reaction NH_(4)HF_(2) electrochemical formation UO_(2)

electrochemical Behaviour of Magnesium（Ⅱ） on Ni Electrode in LiCl-KCl Eutectic

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Chemical Research in Chinese Universities 2018年第1期34卷 107-112页

作者： WANG Shanshan HAN Wei ZHANG Milin LI Mei YANG Xiaoguang SUN Yang Key Laboratory of Superlight Materials and Surface Technology Ministry of Education College of Material Science and Chemical Engineering Harbin Engineering University Harbin 150001 P. R. China

The electrochemical behaviour of magnesium（Ⅱ） and the formation mechanism of Mg-Ni alloys on Ni electrode were studied in LiCl-KCl eutectic using various electrochemical techniques. Cyclic voltammogram and square-wave voltammogram revealed that under-potential deposition of magnesium occurred on Ni electrode because Mg-Ni alloy compounds were formed. The thermodynamic properties of the Mg-Ni intermetaUics, Mg2Ni and MgNi2, were determined using open circuit chronopotentiometry in the temperature range of 8186893 K. Moreover, the Mg-Ni alloys were produced by potentiostatic and galvanostatic electrolysis under different conditions and characterized by means of scanning electron microscopy（SEM） equipped with energy dispersive spectrometry（EDS） and X-ray diffraction（XRD）. The experimental results indicate that Mg-Ni intermetaUic compounds can be selectively produced by potentiostatic electrolysis.

关键词： electrochemical behaviottr Mg-Ni alloy electrochemical formation Ni electrode Molten chloride