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Valence states, impurities and electrocrystallization behaviors during molten salt electrorefining for preparation of high-purity titanium powder from sponge titanium

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Transactions of Nonferrous Metals Society of China 2014年第2期24卷 553-560页

作者：翁启刚李瑞迪袁铁锤李健贺跃辉中南大学粉末冶金国家重点实验室长沙410083

High-purity titanium powder was prepared by molten salt electrorefining from sponge titanium in NaCl-KCl-TiClx salts. The titanium valence, purity and electrocrystallization during electrolysis process were studied. The XPS analysis showed that the titanium valences are mainly ＋4, ＋3 and ＋2 at the earlier, medium and later stages of electrolysis, respectively. During the electrolysis process, the contents of impurities Si, Cr, Mn, Al vary little, and the contents of impurities Fe, Cu, Ni decrease markedly, while the contents of impurities O, N, H increase obviously. The residual impurities are usually distributed in small tunnel of dendritic crystals. Enhancing the electrolysis temperature and prolonging the electrolysis time can increase the titanium particle size. The TEM analysis showed that the electrodeposited titanium is not a single crystal, but contains many nanostructured grains and subgrains, with grain size of 100-500 nm. The electrolysis mechanisms were also discussed.

关键词： molten salt electrolysis high-purity titanium powder valence electrocrystallization

electrocrystallization of Monodisperse Nanocrystals Copper on Highly Oriented Pyrolytic Graphite Electrode

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Electrocrystallization of Monodisperse Nanocrystals Copper o...

Novel Nanostructured MnO_2 Prepared by Pulse Electrodeposition:Characterization and Electrokinetics

2004年全国电子电镀学术研讨会

作者： Huang Ling Yang Fang Zu Zheng Xue Qing Zhong Xiao Hui Xu Shu Kai Zhou Shao Min (Department of Chemistry,Xiamen University,Xiamen,Fujian 361005,China)

Mechanism of copper electrocrystallization on HOPG electrode from a solution of 1 mM CuSO and 1.0 M HSO has been studied using cyclic voltammogram and *** results show that in copper electro-deposition the charge-transfer step is fast and the rate of growth is controlled by the rate of mass transfer of copper ions to the growing *** of Cu(Ⅱ) ions did not undergo underpotential *** initial deposition kinetics of Cu electrocrystallization corresponds to a model including progressive niicleation and diffusion controlled *** nanocrystals with size of 75.6 nm and *** 9%can be obtained by modulation potential electro-deposition.

关键词： electrocrystallization electrodeposition nucleation and growth nanocrystal copper

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Journal of Materials Science & Technology 2008年第6期24卷 857-862页

作者： H.Adelkhani M.Ghaemi S.M.Jafari Department of Chemistry School of SciencesTarbiat Modares UniversityP.O.Box 14115-175TehranIran Department of Chemistry Science FacultyGolestan UniversityP.O.Box 49138-15739GorganIran Department of Mathematics Science FacultyGolestan UniversityGorganIran

Pulse current technique was applied for the preparation of novel electroactive manganese dioxide and possible influences of different electrokinetic phenomena on material characteristics were discussed. The characterizations of pulse deposited sample （pcMD） were carried out by different techniques： Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM）, X-ray diffraction （XRD）, Brunauer-Emmett-Teller （BET） method, Raman spectroscopy, and atomic force microscopy （AFM）. SEM image revealed that pulse current could improve the current distribution. This was confirmed by AFM images showing a decrease in surface roughness of pcMDs in comparison to amorphous samples, which were deposited by direct current （dcMD）. Higher distortion of MnO6 octahedral environment of dcMD was detected by FTJR and Raman spectroscopy. Cyclic voltammetric （CV） measurements showed a generally higher energy level drained from the second electron discharge of pcMD. This is mainly attributed to a higher surface area and a lower diffusion pass of electrons and protons arisen via a rather unique nanostructural arrangement of pcMD grains. Results indicate a higher surface area available for the non homogenous second electron discharge of pcMD grains.

关键词： Manganese dioxide Pulse electrodeposition Nano-structures electrocrystallization

Controllable phase transformation and improved thermal stability of nickel on tungsten substrate by electrodeposition

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Journal of Materials Science & Technology 2019年第5期35卷 727-732页

作者： Minjie Xu Chao Hu Haiyan Xiang Haozi Lu Travis Shihao Hu Bonian Hu Song Liu Gang Yu Institute of Chemical Biology and Nanomedicine (ICBN) State Key Laboratory of Chemical/Biosensing and Chemometrics College of Chemistry and Chemical Engineering Hunan UniversityChangsha410082China Department of Mechanical Engineering California State University Los AngelesCA90032USA Department of Materials and Chemical Engineering Hunan Institute of Technology Hunan Hengyang 421002 China

Present study reports a controllable phase transformation of nickel(Ni) from amorphous to cubic crystal structures on tungsten(W) substrate by electrodeposition. X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy were used to characterize the microstructure, micro-constituents and surface morphology of as-prepared Ni. The microstructure of Ni was strongly affected by the applied overpotential and deposition time. It is demonstrated that by controlling these two parameters either amorphous or cubic crystal structure of Ni on the W substrate could be obtained. The crystallization mechanism is discussed based on Gibbs crystal growth theory and Ostwald’s rule. It is concluded that W substrate, acting as a heat sink, can effectively promote the thermal stability of amorphous Ni, based on the data from differential scanning calorimetry and Kissinger’s model. This work contributes to the elucidation of the crystallization mechanism of Ni on W powder substrates, and proves that, better than alloying with other elements, incorporating powder substrates will significantly improve the crystallization temperature, hence the thermostability of amorphous Ni.

关键词： Phase transformation Amorphous Ni Electrodeposition electrocrystallization Thermal stability

Effect of 2-butyne-1, 4-diol on silver electrodeposition from 5, 5-dimethyl hydantoin solutions

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Rare Metals 2006年第z2期25卷 255-259页

作者： LU Junfeng AN Maozhong ZHENG Huanyu Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China Department of Applied Chemistry Harbin Institute of Technology Harbin 150001 China

The effect of 2-butyne-1, 4-diol on silver electrodeposition process from 5, 5-dimethyl hydantoin solutions was investigated by means of cyclic voltammetric measurement, scanning electron microscopy (SEM) and X-ray diffraction (XRD). Cyclic voltammetric studies indicate that the reduction process of silver electrodeposition is influenced by adding 2-butyne-1, 4-diol. Owing to its adsorption on the electrode surface, 2-butyne-1, 4-diol moderately hinders the mass transfer of the silver complexed ions from the bulk solution to the outer limit of the electrode double layer and affects the electrocrystallization step. Scanning electron microscopy analysis reveals that the presence of 2-butyne-1, 4-diol in the electrolyte is beneficial and the silver deposits obtained are smoother, more compact and more leveled. X-ray diffraction analysis of the silver deposits obtained at 0.5 g·L-1 2-butyne-1, 4-diol indicated that the (110) plane is the most preferred plane and is not affected by the presence of 2-butyne-1, 4-diol in the electrolyte.

关键词： silver electrodeposition 5, 5-dimethyl hydantoin solutions 2-butyne-1, 4-diol electrocrystallization

Potentiostatic deposition of differently shaped Pt and PtBi nanoparticles

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Rare Metals 2013年第4期32卷 375-379页

作者： Min-Li Yang School of Materials Science and Engineering Shijiazhuang Tiedao University

This article presents a comparative study of the deposition behaviors of Pt and PtBi nanoparticles on glassy carbon. Sea-urchin-like Pt nanoparticles and spherical PtBi nanoparticles were produced by potentiostatic deposition. Chronoamperometric characterizations show that the Pt electrodeposition corresponds to the mechanism for 3D progressive nucleation and growth. The sea-urchin-like morphology can be attributed to the effect of applied potential and the electroadsorption of hydrogen and trace Cl^-. The PtBi electrodeposition fits well to the mechanism for 2D progressive nucleation at t/tmax 〈 1.5, and there is a transition from 2D adlayer to 3D clusters at t/tmax 〉 1.5. The spherical PtBi nanoparticles result from the three effects caused by bismuth co-electrodeposition： higher overpoten-tial, strengthened affinity to Cl^-, and improved hydrogen evolution. These results suggest that the adsorption of solution anions and cations on the deposit surface can be used to change the morphologies of the deposits.

关键词： Platinum Bismuth electrocrystallization Nanoparticles Adsorption

Controlled Growth Morphology of Porous Nanocrystal Iron Oxide by Electrodeposition

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Chemical Research in Chinese Universities 2009年第5期25卷 595-599页

作者： LI Li SHI Ke-ying Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education Laboratory of Physical Chemistry School of Chemistry and Materials Science Heilongjiang University Harbin 150080 P. R. China

Fe（Ⅱ） was deposited into the bottom of the mesopores of highly ordered large caged cubic mesoporous silica by electrodeposition. And the deposited Fe mesoporous silica thin film was treated by 1%---4% HF to remove the SiO2 template and then calcined. It was found that nanowire bundles, dendritic plates of porous iron oxide, dense parallel backbones of porous iron oxide were obtained at -1.4-- -1.6 V and 0.08--0.1 mol/L electrolyte concentration after calcinations; the dendritic pattern of porous iron oxide film templated by the SBA-16 film was obtained in macrostructure at a higher absolute value of cathode potential（-1.7-- -1.8 V） and a lower electrolyte concentration（0.02-0.05 mol/L）, the dendritic pattern of porous iron oxide film could copy the microstructure of SBA-16 film; Fe（II） nanowires grew and formed in one dimension（1D） and two-dimension（2D） electrocrystallization at a potential of-l.6-- -1.7 V and an electrolyte concentration of 0.05 mol/L, and the shape of the ID or 2D crystalline iron oxide nanowires calcined was similar to the original shape of the SBA-16 channels. The desired morphology and size of porous nanocrystal iron oxide can be obtained by adjusting the applied potential value and electrolyte concentration, and all kinds of morphologies of porous nanostructure crystal iron oxide can be prepared.

关键词： electrocrystallization Deposition Porous iron oxide Morohology

STUDY THE INFLUENCE OF H_(3)BO_(3)ON THE ZINC ELECTROPLATING USING ELECTROCHEMICAL NOISE TECHNIQUE

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Acta Metallurgica Sinica(English Letters) 2004年第5期17卷 661-666页

作者： Z.Zhang C.S.Wu Q.Y.Cai Y.L.Cheng F.H.Cao J.Q.Zhang C.N.Cao DepartmentofChemistry ZhejiangUniversityHangzhou310027China StateKeyLaboratoryforCorrosionandProtection InstituteofMetalResearchTheChineseAcademyofSciencesShenyang110016China

The influence of H3BO3 on the zinc electroplating was studied using electrochemical noise technique, cyclic voltammetry and steady-state polarization method. The results showed that, under the experimental conditions, the deposition of zinc followed the mechanism of two-dimensional nucleation and subsequent grain growth. The addition of H3BO3 into the electroplating solution prominently changes the nucleation and growth kinetics of zinc deposits, which is directly related to the features of electrocrystallization noise and the corresponding structure of the electrodeposits. The results also shown that the electrochemical noise (EN) technique can give more information about the electrodeposits structure and electroplating mechanism than other normal electrochemical measurements can give, such as steady-state polarization method and cyclic voltammetry technique.

关键词： zinc electroplating electrochemical noise electrocrystallization

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某些添加剂对镍在玻璃碳上电结晶的影响

厦门大学学报(自然科学版) 1987年第6期 705-711页

作者：许书楷周绍民厦门大学物理化学研究所厦门大学化学系

用阶跃电位法研究了光亮镍Watts镀液中添加剂:糖精、丁炔二醇和香豆素,对镍在玻璃碳上沉积初始阶段的影响.结果表明,在不含添加剂的该电解液,镍电结晶的初始阶段按连续成核的三维生长机理进行;分别或同时含有糖精和丁炔二醇时,则按瞬时... 详细信息

用阶跃电位法研究了光亮镍Watts镀液中添加剂:糖精、丁炔二醇和香豆素,对镍在玻璃碳上沉积初始阶段的影响.结果表明,在不含添加剂的该电解液,镍电结晶的初始阶段按连续成核的三维生长机理进行;分别或同时含有糖精和丁炔二醇时,则按瞬时成核的三维生长机理进行.糖精或丁炔二醇促进成核过程而阻化晶核的生长,这两种添加剂同时存在时则对成核和三维生长都起促进作用;添加香豆素或者同时添加三种添加剂不改变成核和生长的方式,但香豆素对成核过程和晶核生长都起着促进作用,而三种添加剂混用则对成核和生长过程起着阻化作用.本文采用Fleischmann等人郝二建模型.

关键词： Electrodeposition electrocrystallization Additive Nickel Electrochemical nucleation