研究者データベース

上田 幹人(ウエダ ミキト)
工学研究院 材料科学部門 エコマテリアル分野
教授

基本情報

所属

  • 工学研究院 材料科学部門 エコマテリアル分野

職名

  • 教授

学位

  • 博士(工学)(北海道大学)

J-Global ID

研究キーワード

  • ナトリウム   機能性ガラス   イオン交換   イオン液体   溶融塩   化合物半導体   選択性電析   アルミニウムドロス   電解採取   Bi-Sb-Te   不働態皮膜   鉄   ルミネッセンス   チタン   耐食性   光励起   ステンレス鋼   薄膜   水素貯蔵   耐食皮膜   溶融塩電解   水素化リチウム   

研究分野

  • ナノテク・材料 / 金属生産、資源生産
  • ナノテク・材料 / 無機物質、無機材料化学
  • ナノテク・材料 / 材料加工、組織制御

所属学協会

  • アメリカ電気化学会   日本化学会   日本工学教育協会   日本鉄鋼協会   日本金属学会   腐食防食協会   表面技術協会   電気化学会   

研究活動情報

論文

  • Rei Esaki, Yohei Yasuda, Norito Kotani, Hisayoshi Matsushima, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 169 8 2022年08月 
    Polyethylene glycol (PEG) plays an important role as an inhibitor of the electrodeposition. In this study, we investigated the potential dependence of PEG (molecular weight: 3000) adsorption and desorption processes on the gold single crystal substrate. High speed atomic force microscope (HS-AFM) was applied for observing the dynamic behaviors of the nucleation and the growth of PEG adsorption. The in situ observation was conducted at the several potentials where the cyclic voltammogram measurement showed the broad peak of the reduction current. As the applied potential became more cathodic, the adsorption morphology changed from film-like, through the sphere, to the large irregular cluster. When the potential was switched to anodic potential, HS-AFM could show the dissolution process of PEG. Finally we demonstrated the effect of the tip force by modifying the feed-back circuit of AFM.
  • Mashu Mita, Hisayoshi Matsushima, Mikito Ueda, Hiroshi Ito
    Journal of Colloid and Interface Science 614 389 - 395 2022年05月15日 
    The nanobubbles (NB) formed on a solid surface has been reported, although the stability in a solution is still discussed. The atomic force microscopy (AFM) has shown the unique shape of the flatted NB, however the dynamic behavior has not investigated yet. Recently, the high scanning speed AFM (HS-AFM) has been developed and applied to the several interfaces. Here, we present in-situ HS-AFM observation during water electrolysis. The hydrogen and oxygen NB evolution on highly oriented pyrolytic graphite (HOPG) electrode are studied. Our video data is the first time to demonstrate the NB nucleation and the growth. The processes are different between both gases. The hydrogen NB grows with active coalescence, while the oxygen one is smaller and irregularly moves on HOPG surface. Using this technique, we will be able to study the NB stability influence by some factors, such as the surface potential and electric capillarity.
  • Haruka Sato, Hisayoshi Matsushima, Mikito Ueda, Hiroshi Ito
    International Journal of Hydrogen Energy 46 68 33689 - 33695 2021年10月01日 
    Water electrolysis (WE) is a key technology for a decarbonized society and is essential for hydrogen isotope separation for a future fusion reactor. In this study, deuterium (D) separation was performed by anion exchange membrane WE (AEMWE) and compared with our previous results from proton exchange membrane WE (PEMWE). WE allows D to become concentrated in solution and diluted in hydrogen gas compared with the D concentration in feed water. The separation effect increases with decreasing water stoichiometric ratio, λ, of the water feed to electrolysis volume. Owing to little water drainage from the cathode, AEMWE can be performed at λ ≈ 1.05, while λ ≈ 4.0 is the lowest for PEMWE. When the feed rate is reduced (λ < 2), D in the product water becomes more concentrated, which corresponds to a sharp rise in cell voltage owing to the water shortage at the cathode.
  • Tomoki Hirai, Hisayoshi Matsushima, Mikito Ueda
    Journal of the Electrochemical Society 168 8 2021年08月 
    To investigate co-electrodeposition of Al and Sc ions, voltammogram measurements were carried out in LiCl-KCl molten salt containing AlCl3 and ScCl3 at 723 K. In the voltammogram measurements, a cathodic current of Al ions and formation of Al-Sc alloys were observed from 0 V and -0.2 V vs Al/Al(III), respectively. Sponge-like electrodeposit formed on the Cu substrate cathode under the condition of a constant potential electrolysis at -0.4 V. The contents of Al and Sc in the electrodeposit were 73.6 and 8.8 at% by EDS analysis. The X-ray diffraction pattern of the electrodeposit fits the patterns of Al and Al3Sc.
  • Koichi Ui, Satoshi Kobayashi, Kuniaki Sasaki, Tatsuya Takeguchi, Tetsuya Tsuda, Mikito Ueda, Jyunji Nunomura, Yukio Honkawa, Yoichi Kojima
    Journal of The Electrochemical Society 2021年05月01日
  • Tetsuya TSUDA, Kei HOSOYA, Mikito UEDA, Koichi UI, Masao MIYAKE, Junji NUNOMURA, Yoshiyuki OYA, Yoichi KOJIMA
    Denki Kagaku 89 1 27 - 31 2021年03月05日
  • Go Kamesui, Kei Nishikawa, Hisayoshi Matsushima, Mikito Ueda
    Journal of The Electrochemical Society 168 3 031507 - 031507 2021年03月01日 [査読有り]
     
    It is important to understand and control corrosion in very small parts. For this purpose, in situ observation of corrosion reactions is necessary. Magnetic fields offer a new way of influencing corrosion reactions. We have investigated the dissolution of a Cu anode in a magnetic field using a holographic laser interferometric microscope. The microscope enables us to quantify the growth of the diffusion layer and the variation in Cu2+ concentration in the vicinity of the electrode. By sandwiching the anode between two doughnut-shaped neodymium magnets, the increase in the surface concentration caused by dissolution is remarkably suppressed, whereas the thickness of the diffusion layer is barely affected. The present results support the hypothesis that mass transport in enhanced in the magnetic field.
  • Risako Tanii, Ryota Ogawa, Hisayoshi Matsushima, Mikito Ueda, Richard Dawson
    International Journal of Hydrogen Energy 46 9 6745 - 6750 2021年02月03日 
    Fuel cells (FC) have been developed for automobiles and stationary power units. In addition to a power generator function, we propose a new application of hydrogen isotope separation. In this paper, deuterium (D) separation is investigated by two types of AFCs with platinum (Pt) or ruthenium (Ru) anode catalysts. The characteristics of the AFCs are evaluated by pure protium (H) or deuterium gas separately. In the case of Pt catalyst, the cell current/voltage curves show similar results for both gases. But a remarkable decrease in the voltage value is observed probably due to the mass transportation (diffusion) limitation at Ru catalyst. The limitation effect was larger for D2 than H2 gas. The AC impedance measurements supports the slow reaction rate of D2 gas on Ru catalyst. The separation experiments are verified with hydrogen gas mixed with 1 at% D. The D is diluted in the unreacted gas discharged from AFC with Pt catalyst, but it is concentrated with Ru one. The inverse response may be attributed to the elementary process of the hydrogen oxidation reaction and the difference in the adsorption energy of gas and water molecules on the catalyst surface.
  • Effects of water transport on deuterium isotope separation during polymer electrolyte membrane water electrolysis
    Kenji Harada, Risako Tanii, Hisayoshi Matsushima, Mikito Ueda, Koki Sato, Takahide Haneda
    International Journal of Hydrogen Energy 45 31389 - 31395 2020年11月 [査読有り]
  • Effect of high magnetic field on aluminum electrodeposition using an ionic liquid
    Hisayoshi Matsushima, Hitomi Takahashi, Tatsuki Suzuki, Mikito Ueda, Iwao Mogi
    Electrochemistry Communications 115 106733  2020年10月 [査読有り][通常論文]
  • Koichi Ui, Satoshi Kobayashi, Tatsuya Takeguchi, Tetsuya Tsuda, Mikito Ueda, Jyunji Nunomura, Yukio Honkawa, Yoichi Kojima
    ECS Transactions 2020年09月23日 [査読有り][通常論文]
  • Corrosion behavior of SUS304L Steel in pH 13 NaOH Solution
    T. Nakagawa, H. Matsushima, M. Ueda, H. Ito
    Electrochemistry 88 468 - 474 2020年08月 [査読有り][通常論文]
  • In Situ Measurement of Al3+ concentration Profile during Al Anodization using Degital Holographic Interferometic Microscope
    Akinori Miki, Kei Nishikawa, Takahiro Ozawa, Hisayoshi Matsushima, Mikito Ueda
    J. Electrochem. Soc. 167 062501  2020年05月 [査読有り][通常論文]
  • Aluminium-Poly(3,4-ethylenedioxythiophene) Rechargeable Battery with Ionic Liquid Electrolyte
    T. Shoetz, Ben Craig, Carlos Ponce de Leon, Andreas. Bund, Mikito. Ueda, Chee Tong John Low
    Journal of Energy Strage 28 101176  2020年03月 [査読有り][通常論文]
  • 補助電極を用いたEmImCl-AlCl3イオン液体からの光沢アルミニウム電解めっき膜とそのアルマイト処理
    平井友樹, 松島永佳, 上田幹人
    表面技術 71 1 32 - 36 2020年01月 [査読無し][通常論文]
  • Daiki Nakajima, Tatsuya Kikuchi, Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda, Ryosuke O. Suzuki, Shungo Natsui
    Materials 12 3497  2019年11月 [査読有り][通常論文]
  • Hisayoshi Matsushima, Ryota Ogawa, Mikito Ueda
    International Journal of Hydrogen Energy 44 29 15436 - 15440 2019年06月07日 
    © 2019 Hydrogen Energy Publications LLC The separation of hydrogen isotopes has important applications for fundamental science and nuclear engineering. This study investigates isotope separation by stacked polymer electrolyte fuel cells that form part of a combined electrolysis and fuel cell (CEFC) system. Fuel gas containing deuterium (D) was generated by water electrolysis and passed through three fuel cells (FCs) connected in series. Increasing the number of operating FCs in the series greatly improved D separation, but had only a modest impact on power consumption. When all three FCs were individually controlled, the separation efficiency depended on the power condition in each FC. At high current the separation factor of the CEFC system reached over 100 owing to the relationship between fuel gas utilization and separation efficiency.
  • Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda
    Electrochimica Acta 302 422 - 427 2019年04月 
    © 2019 Elsevier Ltd We studied the early stages of Cu electro-deposition and -dissolution on Au(111) over a wide overpotential regime by using high speed atomic force microscopy (HS-AFM) with a high temporal resolution. The HS-AFM images revealed an instantaneous nucleation mechanism where epitaxial nuclei were created at a low cathode overpotential. Nuclei with straight edges were caused by the influence of the Au(111) lattice, whereas arched and uneven edges were associated with rapid structural fluctuations of Cu adatoms. For deposits formed at a high overpotential, many fine column-like deposits covered the whole surface plane and the number of Cu nuclei increased with the cathode overpotential. These features were related to the masstransportation. Furthermore, we observed small clusters, a few nm in size, which remained on the substrate after the rapid dissolution process.
  • Takahiro Matsuzaki, Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi, Mikito Ueda
    Materials Transactions 60 3 386 - 390 2019年03月 [査読有り][通常論文]
  • Takahiro Matsuzaki, Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi, Mikito Ueda
    Materials Transactions 60 3 411 - 415 2019年03月 [査読有り][通常論文]
  • Kei Nishikawa, Takaki Saito, Hisayoshi Matsushima, Mikito Ueda
    Electrochimica Acta 297 1104 - 1108 2019年02月20日 
    © 2018 Elsevier Ltd We measured the concentration boundary layer during copper electrodeposition in a copper sulfate solution under an applied magnetic field. Using a holographic laser interference microscope, we demonstrated the formation of the diffusion layer near the cathode. In the initial stage of electrodeposition, the diffusion layer was distorted in a magnetic field. An analysis of the electrode surface concentration supported the following assertions: without a magnetic field, dendrites formed when the surface concentration of Cu2+ was depleted; with a magnetic field, the unique convection phenomena of the field gradient force and localized Lorentz force promoted Cu2+ mass transport in the diffusion layer, producing large crystal grains.
  • Risako Tanii, Ryota Ogawa, Hisayoshi Matsushima, Mikito Ueda
    International Journal of Hydrogen Energy 44 3 1851 - 1856 2019年01月15日 
    © 2018 Hydrogen Energy Publications LLC Processes for separating hydrogen isotopes are important for future energy applications. Several separation methods are based on electrolytic process; however, electrolysis consumes large amounts of electric energy. In this study, we demonstrate deuterium isotope separation from a mixture of H 2 and D 2 gases using a polymer electrolyte fuel cell stack. To identify the most efficient process, we investigated two flow patterns for the fuel gas, namely, parallel and serial flow. The electrical power of the stacks depended on the flow pattern when a high current was generated. We attribute this dependence on membrane dehydration and water droplet formation in the serial flow, which passed through the single cells in a straight path. However, the stack with the serial path showed a high separation factor (α = 6.6) indicating enrichment of deuterium water during the operation. The long reaction path of the fuel gas contributed to effective separation. The fuel utilization in individual cells suggested the potential for even more effective separation processes by a serial flow path.
  • Hisayoshi Matsushima, Hanako Sato, Mikito Ueda, Hiroshi Ito
    Journal of the Electrochemical Society 166 10 F566 - F568 2019年 
    © 2019 The Electrochemical Society. Electrolytic deuterium (D) separation from protium-containing solution has been investigated. Proton (PEM) and anion exchange membrane (AEM) electrolysis were performed at constant current. The mass analysis of hydrogen gas and water vapor was carried out. For both PEM and AEM electrolysis, the D concentration in the evolved hydrogen gas was lower than that of the initial electrolytic solution. The D concentration in the water vapor was unchanged by PEM electrolysis, but was increased by AEM. The separation factor of PEM was smaller than that of AEM, which was attributed to the humidification state on platinum catalyst.
  • Shota Kaneko, Hisayoshi Matsushima, Mikito Ueda
    Keikinzoku/Journal of Japan Institute of Light Metals 69 1 42 - 45 2019年 
    © 2019 The Japan Institute of Light Metals. To form Al-Mn-Zn ternary alloy film, electroplating experiments were carried out in low temperature AlCl 3 - NaCl-KCl molten salt at 423 K. In voltammogram measurement, Mn ions were reduced with Al ions at lower than -0.08 V vs. Al/Al(III) in AlCl 3 -NaCl-KCl melt containing MnCl 2 . Zn ions reduction started at 0.2 V in the melt containing ZnCl 2 and the reduction current increased with increasing ZnCl 2 concentration. Compositions of Al-Mn-Zn alloy were changed by ZnCl 2 concentration and electrolysis potential. A relatevely glossy surface was formed in 91at%Al-8at%Mn-1at%Zn alloy and a dull surface was formed in 90at%Al-8at%Mn-2at%Zn alloy. In XRD measurement, intensity of amorphous phase decreased with increasing Zn concentration in the alloys.
  • 兒島 洋一, 津田 哲哉, 宇井 幸一, 上田 幹人, 三宅 正男
    軽金属 69 1 15 - 21 2019年01月 [査読有り][招待有り]
  • Interaction of Localized Surface Plasmons of a Silver Nanosphere Dimer Embedded in a Uniform Medium: STEM-EELS and DDA Simulation
    N. Sakaguchi, S. Matsumoto, Y. Kunisada, M. Ueda
    The Journal of Physical Chemistry C 123 6735 - 6744 2019年 [査読有り][通常論文]
  • Ryota Ogawa, Risako Tanii, Richard Dawson, Hisayoshi Matsushima, Mikito Ueda
    Energy 149 98 - 104 2018年04月15日 [査読有り][通常論文]
     
    The framework about combined electrolysis fuel cell (CEFC) was reported previously [H. Matsushima et al., Energy, 2005 30 2413]. The purpose of the present study focused on measuring the separation factor and the energy reduction by assembling CEFC system. The separation of deuterium was studied with a 1-M KOH electrolyte containing 10 at% deuterium. Polarization plots of alkaline water electrolysis (AWE) revealed relationships between the catalytic activity of the hydrogen evolution reaction and the deuterium separation factor. The power loss was mainly attributed to gas bubble evolution. For polymer electrolyte fuel cells (PEFCs) with a Pt catalyst, approximately 21% of the electrical energy could be recovered by reusing hydrogen gas produced by the AWE. Furthermore, the PEFC could efficiently dilute protium in the gas phase, resulting in a high separation factor of 30.2 for the CEFC.
  • T. Schoetz, C. Ponce de Leon, A. Bund, M. Ueda
    Electrochemistry Communications 89 52 - 56 2018年04月01日 [査読有り][通常論文]
     
    This work shows the electro-polymerisation of thin film poly(3,4-ethylenedioxythiophene) on three-dimensional reticulated vitreous carbon substrates by cyclic voltammetry and pulsed polymerisation methods from a Lewis neutral chloroaluminate ionic liquid containing 3,4-ethylenedioxythiophene monomer. The polymer composite is attractive as an energy storage electrode for sustainable and high-performance technologies due to its unique properties of battery and capacitor in one system, i.e., the redox reaction occurring simultaneously with the anion doping/de-doping of the conductive polymer with AlCl4 − ionic species contained in the ionic liquid. The structure of the polymer films, their doping/de-doping mechanism and the stability in the ionic liquid were characterised by scanning electron microscopy and cyclic voltammetry and compared with films electro-polymerised on planar vitreous carbon. The typical granular and nano/micro-porous polymer structure observed on planar vitreous carbon was successfully replicated on the macro-porous reticulated vitreous carbon surface. The polymer films show approximately 45% higher capacity than films on planar substrates and similar efficient redox behaviour, proving that the material has hybrid battery-capacitor properties enhanced by the higher area per unit volume of reticulated vitreous carbon.
  • T. Schoetz, C. Ponce de Leon, A. Bund, M. Ueda
    Electrochimica Acta 263 176 - 183 2018年02月10日 [査読有り][通常論文]
     
    This work studied the electro-polymerisation of 3,4-ethylenedioxythiophene (EDOT) and its electrochemical behavior in Lewis acidic, neutral and basic chloroaluminate ionic liquid 1-ethyl-3-methylimidazolium chloride aluminum chloride (EMImCl-AlCl3) by cyclic voltammetry. It was found that the electro-polymerisation on vitreous carbon only occurs in Lewis neutral EMImCl-AlCl3 as a dark blue-violet film whereas the electro-polymerisation in a Lewis acidic or basic compositions is not possible due to the interactions between the conductive polymer and the ionic liquid as well as the potential stability limits of the electrolyte. PEDOT films synthesised in Lewis neutral ionic liquid were tested in monomer-free Lewis acidic, basic and neutral EMImCl-AlCl3 and show different doping and de-doping behavior for chloride ionic species. The PEDOT films in a Lewis neutral composition showed higher doping levels due to the higher potential stability window, up to 2.6 V vs. Al|Al(III) than in a Lewis acidic and basic solutions. Furthermore, it was shown that the doping and de-doping levels are predefined during the electro-polymerisation of PEDOT. The anion doping and de-doping reaction reached 97% reversibility in the neutral composition, which suggests that PEDOT is a suitable electrode material to store charged species in this media and could be used in rechargeable energy storage devices.
  • Removal of Ca and K from Metallic Na in TFSI Ionic Liquids Using an Exchange Reaction
    水上俊太, 松島永佳, 上田幹人
    J. Electrochem. Soc. 165 D94 - D97 2018年02月 [査読有り][通常論文]
  • 上田幹人
    Electrochemistry Communications 92 29 - 32 2018年 [査読有り][通常論文]
     
    © 2018 Elsevier B.V. The initial stages of Cu electrodeposition and dissolution on an Au(100) electrode in sulfuric acid solution were studied by high-speed atomic force microscopy. Dynamic observations revealed that Cu islands formed on the Au terraces within a few seconds. The islands grew to approximately 100 nm as two thick layers overlapped. The AFM height profile results indicated that each layer consisted of 3–8 atomic layers. Dissolution occurred when an anodic potential was applied, with the bottom layer dissolved preferentially. Correlation of these observations with electrochemical data from cyclic voltammetry indicated differences in the rates of deposition and dissolution.
  • Understanding the charge storage mechanism of conductive polymers as hybrid battery-capacitor materials in ionic liquids by in-situ atomic force microscopy and electrochemical quartz crystal microbalance studies
    上田幹人
    Journal of Materials Chemistry A6 17787 - 17799 2018年 [査読有り][通常論文]
  • Mikito Ueda, Shiori Honda, Hisayoshi Matsushima
    Electrochemistry 86 2 69 - 71 2018年 [査読有り][通常論文]
     
    To enhance three phase interfaces on graphite cathodes in an Al-Cl2 cell, graphite cathodes with different densities (1.27, 1.32, 1.40, 1.57, and 2.00gcm-3) were evaluated in an 1-ethyl-3-methylimidazolium chloride -AlCl3 mixture ionic liquid electrolyte at 313 K. The relation between current and cell voltage or power and current of the 1.27gcm-3 graphite cathode showed the best performance among the graphite materials with 5 graphite densities in the cathodes investigated here. Surface profiles of the graphite by mercury intrusion porosimetry suggested that there are effective pore diameters for penetration of the electrolyte, lower density graphite has more pores on the surface than graphite with higher densities.
  • Masato Onishi, Hisayoshi Matsushima, Mikito Ueda, Kota Washio, Akira Kato
    Electrochemistry 86 2 66 - 68 2018年 [査読有り][通常論文]
     
    To clarify the relationship between adhesive strength of Al electroplating film and Mg alloy substrate, the amounts of γ-phase (Mg17Al12) and α-phase (Mg solid solution phase) in Mg alloy surface was investigated. Al electroplating film on Mg alloy was formed by current pulse electrolysis in AlCl3-1-ethyle-3-methyl-imidazolium chloride mixture ionic liquid at 283 K. It was found that the adhesive strength was affected by the ratio of γ-phase in the Mg alloys and it increased with increasing ratios of γ-phase on the Mg alloy surface. The results suggest that the adhesive strength of the electrodeposits on the γ-phase is stronger than that of the α-phase due to little oxide formation on the γ-phase.
  • T. Schoetz, M. Ueda, A. Bund, C. Ponce de Leon
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 21 11 3237 - 3246 2017年11月 [査読有り][通常論文]
     
    This paper presents a feasibility study of a non-aqueous rechargeable battery based on aluminum and poly-(3,4-ethylenedioxythiophene) conductive polymer in a chloroaluminate ionic liquid. The polymer was electrodeposited on a vitreous carbon working electrode in a chloride aqueous solution and the structure was analyzed by scanning electron microscopy. The doping/de-doping mechanism of chloride ions into the polymer structure was studied using a quartz crystal microbalance and cyclic voltammetry. The deposition/dissolution of the aluminum negative electrode were investigated by electrochemical and microscopic methods. Performance data were obtained with a laboratory-scale aluminum-conductive polymer battery at constant current showing an average cell discharge voltage of 1 V and specific energies of at least 84 Wh kg(-1) referred to the mass of the polymer and aluminum. The system is novel and the paper outlines further research to improve the cell performance.
  • Hisayoshi Matsushima, Ryota Ogawa, Shota Shibuya, Mikito Ueda
    MATERIALS 10 3 303  2017年03月 [査読有り][通常論文]
     
    The use of a polymer electrolyte fuel cell (PEFC) with a Nafion membrane for isotopic separation of deuterium (D) was investigated. Mass analysis at the cathode side indicated that D diffused through the membrane and participated in an isotope exchange reaction. The exchange of D with protium (H) in H2O was facilitated by a Pt catalyst. The anodic data showed that the separation efficiency was dependent on the D concentration in the source gas, whereby the water produced during the operation of the PEFC was more enriched in D as the D concentration of the source gas was increased.
  • Mikito Ueda
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 21 3 641 - 647 2017年03月 [査読有り][招待有り]
     
    Studies using low-temperature chloroaluminate molten salts are introduced. The physical and chemical properties have been elucidated from around the 1930s, and electrodeposition of Al alloys was reported more recently. Electrodeposition of Bi, Sb, and Te using an AlCl3-NaCl-KCl molten salt is also introduced as an application of molten salts.
  • T. Schoetz, C. Ponce De Leon, M. Ueda, A. Bund
    Journal of the Electrochemical Society 164 14 A3499 - A3502 2017年 [査読有り][通常論文]
     
    The main challenges to implement sustainable energy storage technologies are the utilization of earth-abundant recyclable materials, low costs, safe cell reactions and high performance, all in a single system. Aluminum batteries seem to cover these requirements. However, their practical performance is still not comparable with the state of the art high performance batteries. A key aspect to further development could be the combination of aluminum with charge storage materials like conductive polymers in non-aqueous electrolytes taking advantage of the properties of each material. This reviewpresents the approaches and perspectives for rechargeable aluminum-based batteries as sustainable high-performance energy storage devices.
  • 高橋久智美, 行方千賀, 菊地竜也, 松島永佳, 上田幹人
    表面技術 68 4 208 - 212 表面技術協会 2017年 [査読有り][通常論文]
  • Hitomi Takahashi, Hisayoshi Matsushima, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 164 8 H5165 - H5168 2017年 [査読有り][通常論文]
     
    The surface structure of Al films electrodeposited in a magnetic field was studied in a AlCl3-1ethyl-3methylimidazolium chloride (EMIC) mixture ionic liquid, focusing on the surface morphology and crystal orientation. Current-dependent measurements reveal two preferential orientations. First, at small current densities (i < 10 mA cm(-2)), a (111) plane is preferentially oriented parallel to the surface where no magnetic field is detected. Second, at high current densities (i > 10 mA cm(-2)), a (200) plane is selectively grown, where the mass transportation of Al(III) is promoted by magneto-hydrodynamic (MHD) convection. Correlations of these data with scanning electron microscope observations showing tabular-facet formation in the magnetic field suggest that these structural variations are induced by microscopic MHD, demonstrating the difference between this process and that existing in an aqueous system. (C) The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.
  • Ellipso-Microscopic Observation of Titanium Surface under UV-Light Irradiation
    K. Fushimi, K. Kurauchi, T. Nakanishi, Y. Hasegawa, M. Ueda, T. Ohtsuka
    Corrosion Science and Technology 16 2 265 - 270 2017年 [査読有り][通常論文]
  • Kazuki Sato, Hisayoshi Matsushima, Mikito Ueda
    APPLIED SURFACE SCIENCE 388 B 794 - 798 2016年12月 [査読有り][通常論文]
     
    To form Al-Ta alloys for high temperature oxidation resistance components, molten salt electrolysis was carried out in an AlCl3-NaCl-KClmelt containing TaCl5 at 423 K. The voltammogram showed two cathodic waves at 0.45 V and 0.7 V vs. Al/Al(III), which may correspond to reduction from Ta(V) to Ta(III) and from Ta(III) to tantalum metal, respectively. Electrodeposits of Al and Ta were obtained in the range from 0.05 to 0.3 V and the highest concentration of Ta in the electrodeposit was 72 at% at 0.3 V. With increasing Ta content in the alloy, the morphology of the electrodeposits became powdery and the particle size smaller. (C) 2016 Elsevier B.V. All rights reserved.
  • Ryota Ogawa, Hisayoshi Matsushima, Mikito Ueda
    ELECTROCHEMISTRY COMMUNICATIONS 70 5 - 7 2016年09月 [査読有り][通常論文]
     
    The separation of deuterium from a hydrogen-deuterium mixture was carried out using an alkaline membrane fuel cell (AMFC) with a Pt catalyst. This novel use of an AMFC to separate deuterium from a mixture of H-2 and D-2 was demonstrated by the production of deuterium-enriched water during power generation by the AMFC. The deuterium separation factor increased with output current (i) to a maximum value of 1.64 attained at i = 30 mA cm(-2). (C) 2016 Elsevier B.V. All rights reserved.
  • Kazuki Sato, Hisayoshi Matsushima, Mikito Ueda
    MOLTEN SALTS AND IONIC LIQUIDS 20 75 15 305 - 312 2016年 [査読有り][通常論文]
     
    To form Al-W alloys for high temperature oxidation resistance components, molten salt electrolysis was carried out in an AlCl3-NaCl-KCl melt containing WCl4 at 423 K. The voltammogram showed two cathodic waves at 1.1 V and 0.5 V vs. Al/Al(III), which may correspond to the reduction from W(IV) to W(III) and from W(III) to tungsten metal, respectively. Electrodeposits of Al and W were obtained in the range from -0.05 to 0.4 V and the highest concentration of W in the electrodeposit was 95 at% at 0.4 V. With increasing W content in the alloy, the morphology of the electrodeposits became more powdery and the particle size smaller.
  • Masato Onishi, Hisayoshi Matsushima, Mikito Ueda, Hiroki Habazaki, Kota Washio, Akira Kato
    ECS Transactions 75 15 297 - 304 2016年 [査読有り][通常論文]
     
    To investigate the relationship between adhesion strength of Al electroplated film and Al concentration in Mg alloy substrates and the grain size of the Mg alloy, Al electroplating was carried out with AZ31, AZ61, AZ91, and of AZ31 with different grain sizes in an ionic liquid of a mixture of aluminum chloride and 1-ethyle-3-methyl-imidazolium chloride at 283 K. Dense Al electrodeposits were formed on all the substrates. The adhesion strength increased with increases in the Al content of the Mg alloys. Increasing the average grain size also resulted in increases in the adhesive strength.
  • 高橋久智美, 行方千賀, 菊地竜也, 松島永佳, 上田幹人
    表面技術 68 208 - 212 2016年 [査読有り][通常論文]
  • 金属・合金電析用の電解質としてのイオン液体の活用
    上田幹人
    表面技術 67 6 - 9 2016年 [査読有り][招待有り]
  • Toshiaki Ohtsuka, Mikito Ueda, Masatoshi Abe
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 163 8 C459 - C469 2016年 [査読有り][通常論文]
     
    The passive oxide film on SUS 304 stainless steel (SS) was studied in a 0.1 mol dm(-3) sulfuric acid solution as a function of passivation time. The passive oxide films were measured by ellipsometry and X-ray photoelectron spectroscopy (XPS). A Mott-Schottky plot of the film capacitance was employed to determine the donor density in the n-type semiconducting oxide film, and current measurements of the Fe3+/Fe2+ redox couple were employed to investigate the electronic transfer process on the passive oxide film. The passive oxide consists of Cr-Fe-Ni oxides in which enrichment of Cr to 57 mol% occurs as the potential increases. During the aging of the passive oxide at 0.6 V vs. Ag/AgCl/saturated KCl (SSC) for 43 ks, the current decreased from 30 mu A cm(-2) at 10 s to 0.025 mu A cm(-2) at 43 ks, and the Cr ratio in the oxide increased from 49 to 57 mol% with an increase in the O2- ratio. Notably, the film thickness remained nearly constant at 1.3 nm during the aging process. Enrichment of the Cr content resulted in a decrease in the donor density of the n-type semiconducting passive oxide and the inhibition of electronic charge transfer from/to the Fe3+/Fe2+ redox couple in the electrolyte. (C) The Author(s) 2016. Published by ECS.
  • Shota Shibuya, Hisayoshi Matsushima, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 163 7 F704 - F707 2016年 [査読有り][通常論文]
     
    Hydrogen evolution and oxidation reactions were studied on a polycrystalline platinum electrode in 0.05 M D2SO4 solution at 298 K by using a rotating disk electrode, focusing on the kinetic isotope effect on reactivity. The polarization measurements in the evolution reaction regime, on the one hand, revealed two Tafel regions: at low overpotentials close to the equilibrium potential, the Tafel slope was 0.039 V dec(-1), suggesting a Volmer-Tafel mechanism; and at potentials around 0.05 V or lower, a slope of 0.168 V dec(-1) indicated that a transition to a Heyrovsky-Tafel mechanism occurred. In the oxidation reaction regime, on the other hand, a single Tafel slope of 0.055 V dec(-1) was observed at potentials of 0.08 V or lower. Comparing between the deuterium and protium data for the kinetic factors supported the presence of an isotope effect, whereby the deuterium was more easily dissociated on the platinum electrode. The present kinetic result supported the deuterium separation of polymer electrolyte fuel cell (PEFC) in which the mixture gases of H-2 and D-2 were purged. The deuterium separation factor increased with increasing in the hydrogen utilization. This suggests a new isotope separation technique and also provides useful data for fuel cells. (C) 2016 The Electrochemical Society. All rights reserved.
  • K. Fushimi, K. Kurauchi, H. Ikeyama, Y. Kitagawa, T. Nakanishi, Y. Hasegawa, M. Ueda, T. Ohtsuka
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 19 12 3579 - 3587 2015年12月 [査読有り][通常論文]
     
    Photo-corrosion of an anodized titanium surface in 0.05 mol dm(-3) sulfuric acid solution was investigated by using an in situ electrochemical ellipso-microscope. Irradiation of ultra-violet (UV) light on an anodized surface, which showed a patch-like bright image on an ellipso-microscopic view due to non-uniform growth of the oxide film, under potentiostatic polarization allowed the flow of a photo-induced anodic current and changed the brightness and patch pattern in the image. This indicates that the irradiation promotes photo-electrochemical reaction, resulting in a change in the thickness and/or structure of the oxide film on the surface. The film change was dependent not only on power density of the irradiation light but also on applied potential during the irradiation and crystallographic orientation of the substrate. Pitting initiation during potentiodynamic polarization in the acid with bromide ions was also monitored using the ellipso-microscope. The irradiation resulted in pitting initiation at lower potentials than those in a non-irradiated condition.
  • Mikito Ueda, Tsubasa Teshima, Hisayoshi Matsushima, Toshiaki Ohtsuka
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 19 12 3485 - 3489 2015年12月 [査読有り][通常論文]
     
    To improve the corrosion resistance of Al in chloride solutions, electrodeposition of Al-Zr alloys of various compositions was carried out at 448 K by constant potential control in AlCl3-NaCl-KCl molten salt containing ZrCl4. Cathodic reduction of the Zr ions starts at a potential of 0.4 V vs. Al/Al(III) in the molten salt. The electrodeposition of Al and Zr occurred at potentials more negative than -0.02 V. The concentration of Zr in the electrodeposit increased to 23 at.% at -0.02 V. In the XRD analysis, the electrodeposits formed at -0.05 to -0.15 V had good crystallinity, the electrodeposits containing higher concentrations of Zr formed at -0.02 or -0.04 V show an amorphous or fine crystal structure. The pitting potentials of Al-Zr alloys containing 5-23 at.% Zr in 0.1 M NaCl solution shifted from +0.1 to +0.3 V compared with those of pure Al.
  • Yu Hang, Hiroki Murakoshi, Mikito Ueda, Kazuhisa Azumi
    Surface & Coatings Technology 270 164 - 169 2015年05月 [査読有り][通常論文]
     
    An intermediate protective layer of Zn was formed on the AZ91D surface to prevent dissolution of the substrate surface and to obtain a uniform deposition layer of Al in an electroplating process from a molten salt bath. Simple zincate treatment did not result in the formation of a Zn layer with sufficient thickness and coverage for substrate protection. Electrodeposition of Zn was thus conducted after the zincating process to thicken the Zn layer. A Zn layer of a few pm irtthickness sufficiently protected the AZ91D substrate. A uniform Al layer was then electrode-posited on Zn-protected AZ91D without degradation of the substrate. Since the Mg alloy surface and Zn surface were not sufficiently active for Zn deposition and Al deposition, respectively, Cu-nanoparticle predeposition was applied to each surface before the electrodeposition processes. (C) 2015 Elsevier B.V. All rights reserved.
  • Tatsuya Kikuchi, Ryoma Ishida, Shungo Natsui, Takehiko Kumagai, Isao Ogino, Norihito Sakaguchi, Mikito Ueda, Ryosuke O. Suzuki
    ECS SOLID STATE LETTERS 4 9 M19 - M22 2015年 [査読有り][通常論文]
     
    The novel fabrication of multi-walled carbon nanotube (MWCNT)/cementite (Fe3C) nanocomposites was demonstrated via the calciothermic reduction of carbon dioxide (CO2) through electrolysis in molten CaCl2/CaO with iron additives at 1173 K. In this technique, CO2 generated from a graphite anode is reduced to carbon with a metallic calcium reductant formed on a graphite cathode via electrolysis in molten salt. Calciothermic reduction without iron additives resulted in the formation of onion-like carbons (OLCs) with spherical graphite layers and thin graphite sheets. In contrast, MWCNT/Fe3C nanocomposites and OLCs were successfully fabricated via calciothermic reduction with iron additives through their catalytic activities. (C) The Author(s) 2015. Published by ECS. All rights reserved.
  • Mikito Ueda, Ryuichi Inaba, Hisayoshi Matsushima, Toshiaki Ohtsuka
    ECS ELECTROCHEMISTRY LETTERS 4 2 E1 - E3 2015年 [査読有り][通常論文]
     
    To develop an electrorefining process for sodium to enable recycling of used sodium-sulfur batteries, a non-aqueous electrolyte with low melting point was investigated. A mixed ionic liquid of NaTFSI (sodium bis(trifluoromethane) sulfonylimide) - TBATFSI (tetrabutylammonium bis(trifluoromethane) sulfonylimide) was selected for the electrolyte. From AC impedance measurements, a maximum ionic conductivity of 16 mS cm(-1) was established of 20 mol% NaTFSI-TBATFSI concentration at 433 K. Electrorefining for 20 hours was carried out with a stable voltage under constant current electrolysis. Liquid pure sodium was electrodeposited by the constant current electrolysis. The calcium content in the sodium cathode was decreased from 250 to 52 ppm by the electrorefining. (C) 2014 The Electrochemical Society. All rights reserved.
  • Hisayoshi Matsushima, Wataru Majima, Yasuhiro Fukunaka, Mikito Ueda
    ECS ELECTROCHEMISTRY LETTERS 4 7 F43 - F45 2015年 [査読有り][通常論文]
     
    Controlling the wetting properties at the three-phase interface is important for improving the performance of alkaline fuel cells. The meniscus of a potassium hydroxide droplet was formed on a nickel electrode, and the interference fringe during the oxygen reduction reaction was observed by confocal laser microscopy. The high spatial resolution of the microscope revealed thin film formation at the meniscus front interface. The thickness decreased with increasing cathodic potential. The generation of microscopic convection by interfacial surface tension may affect mass transfer in the thin film. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.
  • Nan Sheng, Yanhua Lei, Atsushi Hyonoo, Mikito Ueda, Toshiaki Ohtsuka
    PROGRESS IN ORGANIC COATINGS 77 11 1724 - 1734 2014年11月 [査読有り][通常論文]
     
    To improve the protection against the corrosion of AZ91D magnesium alloy provided by conducting polypyrrole (PPy) films, optimization of the electrochemical synthesis of the PPy film was investigated. The bi-layered PPy film was prepared under constant current control, first in a sodium tartrate solution containing molybdate and second in a sodium dodecylsulfate (DS) solution (after the AZ91D alloy was covered by zinc electroplating). Corrosion testing of the zinc-coated AZ91D alloy covered with the PPy film was performed in 3.5% NaCl solution. The more protective PPy film doped with tartrate ions (PPy-Tart film) was formed by the lower current density (CD). Doping of molybdate ions (MoO42-) into the PPy-Tart film significantly improved its corrosion protection properties. When the PPy-Tart-MoO4 layer was covered by an outer PPy layer doped with DS ions, the corrosion protection was further improved. The imposition of ultrasonic waves during the electropolymerization of the inner PPy-Tart-MoO4 layer was effective in the improvement of corrosion protection. The bi-layered PPy-Tart-MoO4/PPy-DS film prepared under ultrasonic irradiation maintained the zinc-coated AZ91D alloy in the passive state during the corrosion test in NaCl solution for 221 h, during which no corrosion products appeared. (C) 2014 Elsevier B.V. All rights reserved.
  • Junji Nunomura, Mikito Ueda, Toshiaki Ohtsuka
    ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS 228 6-7 685 - 689 2014年07月 [査読有り][通常論文]
     
    To improve the reduction efficiency of chlorine electrodes in aluminum-chlorine cells, this reports a circular cone type graphite cathode, with an electrochemical cell consisting of an aluminum anode and the graphite cathode evaluated in EMIC-AlCl3 ionic liquid. The current density in the circular cone type cathodes with different cone angles exhibited a maximum value at 40, and the current density at cell voltage of 0.5 V was about 25 mA cm(-2). This value is about 80% larger than that of a cylindrical type graphite cathode. In a circular cone type cathode with a 40 angle, the maximum power density recorded was 15.3 mW cm(-2).
  • YanHua Lei, Nan Sheng, Atsushi Hyono, Mikito Ueda, Toshiaki Ohtsuka
    PROGRESS IN ORGANIC COATINGS 77 4 774 - 784 2014年04月 [査読有り][通常論文]
     
    Polypyrrole (PPy) films were deposited on copper from "green" inhibitor of phytic acid solution for corrosion protection of copper. The corrosion protection property of the PPy layer was studied by an immersion test in a NaCl aqueous solution. The polymerization process of PPy on copper changed with the pH values of phytic acid solution and current density applied. When one oxidized bare copper in phytic acid solution at various pHs containing pyrrole monomer, a thin layer consisting of complex compound of Cu-phytate was firstly formed, followed by the formation of the PPy layer doped with phytate anion on the complex compound layer. The complex compound layer passivated the copper surface and its thickness increased with the lower pH value of the solution and the lower current density applied. It was found that the PPy coating prepared in the phytic acid solution at pH 4 exhibit the most protective property against copper corrosion. (C) 2014 Elsevier B.V. All rights reserved.
  • Y. H. Lei, N. Sheng, A. Hyono, M. Ueda, T. Ohtsuka
    PROGRESS IN ORGANIC COATINGS 77 2 339 - 346 2014年02月 [査読有り][通常論文]
     
    Benzotriazole (BTA) was added in a conducting Polypyrrole (PPy) film prepared on copper in oxalic acid aqueous solution containing pyrrole monomer to improve corrosion protection by the PPy film and reduce copper corrosion. When BTA was added in the preparation solution, the copper surface was covered by a BTA-Cu complex layer before the anodic polymerization of PPy was started. On the copper surface with the BTA layer, the initial dissolution of copper was inhibited and the PPy polymerization-deposition was started immediately after the anodic current was imposed. The PPy film thus formed was doped with oxalic ions and ionized BTA and was homogeneous in thickness and strongly adhesive. The PPy film containing BTA protected the copper from corrosion in 3.5 wt.% NaCl solution. In 400 h of immersion, copper dissolution was inhibited with 80% protection efficiency relative to that of bare copper. (C) 2013 Elsevier B.V. All rights reserved.
  • Mikito Ueda
    MOLTEN SALTS AND IONIC LIQUIDS 19 64 4 243 - 248 2014年 [査読有り][通常論文]
     
    Electrochemical reactions of metallic sodium were investigated in NaTFSI-TEATFSI ionic liquids and NaTFSI-TBATFSI ionic liquids at 160 degrees C. The melting point of the ionic liquids was 36 degrees C with lowest value in 20 mol% NaTFSI-TEATFSI. The maximum value of electrical conductivity was 36 mScm(-1) at 20 mol% NaTFSI-TEATFSI from the impedance measurement. In the anodic polarization curves, a diffusion limit current was observed at -1.8 V vs. Pt(Q.R.E) at the ionic liquid. The electrorefining experiments for 30 h were carried out at 160 degrees C. After the electrorefining, metallic sodium of 99.99 % purity was obtained by the electrorefining.
  • Wataru Majima, Hisayoshi Matsushima, Yasuhiro Fukunaka, Mikito Ueda
    JOURNAL OF THE ELECTROCHEMICAL SOCIETY 161 10 F1002 - F1005 2014年 [査読有り][通常論文]
     
    The dynamic behavior of the meniscus of a potassium hydroxide and sulfuric acid droplet on a platinum electrode was studied using a charge-coupled device (CCD) camera and confocal laser microscopy. The three-phase interface was investigated during the hydrogen oxidation reaction (HOR) and the hydrogen evolution reaction (HER). Contact angle measurements revealed a spreading interface during the HER whereas the droplet shape remained unchanged during the HOR for both droplets. The overhead view revealed the formation of many fine droplets near the meniscus boundary during the HOR in the alkaline electrolyte, which agrees with previous results for the oxygen reduction reaction (ORR). The correlation of these observations with electrochemical data and differences in the results between the HOR and the HER suggest that the motion of the meniscus was induced by local pH and temperature gradients, presumably caused by a non-uniform reaction because of the limitations of the dissolved gas. (c) 2014 The Electrochemical Society. All rights reserved.
  • YanHua Lei, Nan Sheng, Atsushi Hyono, Mikito Ueda, Toshiaki Ohtsuka
    Corrosion Science 76 302 - 309 2013年11月 [査読有り][通常論文]
     
    Phytic acid (C6H18O24P6), the principal phosphorous storage form in many plant tissues, is a green material. A polypyrrole (PPy) doped with phytic acid (IP6) was electrosynthesised on copper from an aqueous phytic acid solution. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and SEM were used to characterise the polymer. The polymer-covered copper was subjected to a corrosion test in NaCl solution. The dissolution of copper covered with PPy-IP6 was found to be greatly inhibited in NaCl solution. The inhibition indicated protection of the PPy-IP6 layer against copper corrosion. © 2013 Elsevier Ltd.
  • Takahiro Mineta, Seiji Miura, Toshiji Mukai, Mikito Ueda, Tetsuo Mohri
    JOURNAL OF THE JAPAN INSTITUTE OF METALS AND MATERIALS 77 10 466 - 472 2013年10月 [査読有り][通常論文]
     
    In Mg alloys, the most favorable deformation mechanism is the basal slip, and extension twinning also contributes to plastic deformation. Other mechanisms such as prismatic slips, pyramidal slips and twinning except for extension twinning scarcely occur. However, these slip systems also contribute to the plastic deformation of poly crystal Mg alloys, so the determination of CRSS of such non-basal slip systems are inevitable as a basis for the prediction of the deformation behavior of poly-crystal Mg alloys. Because of the difficulty of the evaluation of CRSS for non-basal slip by conventional compression test, newly designed "Pure shear test" is applied to evaluate the CRSS of the prismatic slip Mg alloy single crystals containing Y. Also a modification of Bridgman method using LiF + LiCl is attempted to obtain a pure-Mg single crystal.
  • Mikito Ueda, Hajime Matsunaga, Toshiaki Ohtsuka
    ZEITSCHRIFT FUR PHYSIKALISCHE CHEMIE-INTERNATIONAL JOURNAL OF RESEARCH IN PHYSICAL CHEMISTRY & CHEMICAL PHYSICS 227 8 1097 - 1103 2013年09月 [査読有り][通常論文]
     
    To develop an aluminum-chlorine cell, an electrochemical cell consisting of an aluminum anode and a graphite cathode was developed and evaluated in EMIC-AlCl3 ionic liquid. The open circuit voltage of the aluminum-chlorine cell was about 1.8-1.9 V after introduction of chlorine gas to 66.7 mol % EMIC-AlCl3 at 303 K. The relationship between current density and cell voltage in the cell showed an almost linear relation. The major factor in the voltage drop of the output voltage was considered to be due to resistance of electrolytic melt. The output characteristics of the cell depend on the configuration of the graphite cathode, the current density with a step type cathode at 0.5 V was about 20% better than that of a cylindrical type graphite cathode.
  • Mikito Ueda, Ryuichi Inaba, Toshiaki Ohtsuka
    Electrochimica Acta 100 281 - 284 2013年06月30日 [査読有り][通常論文]
     
    To form Al-Sn alloys for bearing materials, molten salt electrolysis was performed in an AlCl3-NaCl-KCl molten salt containing SnCl 2 at 423 K. The voltammogram showed that the cathodic reduction of the Sn ions started at a potential of 0.5 V vs. Al/Al(III) in the molten salt showing that deposition of pure Sn was possible at 0.5 V. Co-deposition of Al and Sn occurred at potentials more negative than 0.1 V. The co-deposit was composed a solid solution of Al and Sn. The ratio of the Sn in the electrodeposits decreased with the potential from 100 at.% at 0.2 V to 19 at.% at -0.3 V. In the structural observations, electrodeposits with an alternate stacked structure of Al and Sn is obtained at -0.075 V. © 2012 Elsevier Ltd.
  • Mikito Ueda, Kazuya Honda, Toshiaki Ohtsuka
    ELECTROCHIMICA ACTA 100 265 - 268 2013年06月 [査読有り][通常論文]
     
    To develop a electrorefining process of sodium for the recycling of used sodium-sulfur secondary battery, a non-aqueous electrolytic melt was investigated as a candidate for the process. A mixed ionic liquid of NaTFSI (sodium-bis(trifluoremethylsulfonyl)imide)-TEATFSI (tetraethylammonium-bis(trifluoremethylsulfonyl)imide) was selected for the electrolyte, since it has a wide potential window and a weak reactivity with metallic sodium. From AC impedance measurements, the maximum electric conductivity of 36 mS cm(-1) was found for a concentration of 20 mol% NaTFSI-TEATFSI at 433 K. The cathodic deposition of liquid sodium, 99.99% pure, was obtained on a glassy carbon electrode by constant current electrolysis. The calcium concentration in the sodium was decreased from 500 to 12 ppm by the electrorefining. A cathodic current efficiency at 88% was achieved in these electrorefining experiments. (C) 2012 Elsevier Ltd. All rights reserved.
  • Nan Sheng, Mikito Ueda, Toshiaki Ohtsuka
    Progress in Organic Coatings 76 2-3 328 - 334 2013年02月 [査読有り][通常論文]
     
    The electropolymerization of conducting polypyrrole (PPy) film on zinc-coated AZ91D magnesium alloy under constant current control in aqueous sodium tartrate containing pyrrole monomer was investigated using Raman spectroscopy and surface observation. Zinc oxide and zinc hydroxide are initially formed, which are then replaced by a zinc tartrate salt layer. The PPy nucleation is initiated on the zinc layer covered by zinc tartrate, followed by three-dimensional growth of the PPy layer. © 2012 Elsevier B.V.
  • Mikito Ueda, Shizuka Hariyama, Toshiaki Ohtsuka
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 16 11 3423 - 3427 2012年11月 [査読有り][通常論文]
     
    To improve the corrosion resistance of Mg alloys, an Al layer was electrodeposited on the Mg surface from an ionic liquid of 1-ethyl-3-methylimidazolium chloride (EMIC) and aluminum chloride (AlCl3) at 283 K. A smooth surfaced Al electrodeposit can be electroplated in the AlCl3-EMIC ionic liquid by pulse electrolysis at 6.7 Hz and a duty ratio of 0.67. A denser and flatter Al layer was successfully electroplated on AZ121 substrate at the lower temperature of 283 K in an AlCl3-EMIC ionic liquid with 0.1 M ethylene glycol added.
  • Mikito Ueda, Hajime Matsunaga, Toshiaki Ohtsuka, Toshiharu Yamashita
    MATERIALS TRANSACTIONS 53 3 575 - 577 2012年03月 [査読有り][通常論文]
     
    To investigate the diffusion behavior of Tl ions, glass was immersed in TINO3-KNO3 molten salt at 753 K for various lengths of time. The Tl ions embedded in the glass were then reduced to metallic Tl nano-particles by hydrogen at 803 K for 1 h. The depth of the ion exchange layer down to about 140 mu m in the glass was found to be proportional to a square root of the length of immersion time. It was suggested that the ion exchange process is controlled by the diffusion of Tl ions from the surface to the inside. Reduction of Tl ions to metallic Tl with the hydrogen gas occurred only at the surface down to 4 mu m. The concentration profile of the metallic Tl is discussed by nucleation-nucleus growth and the diffusion of Tl ions from deeper areas. [doi:10.2320/matertrans.M2011343]
  • Electrodeposition of Al alloys as a lubricating material in molten salt
    Mikito Ueda
    4th Asian conference on Molten salt chemistry and technology 18 - 23 2012年 [査読無し][招待有り]
  • Electrowinning of Li from LiOH by BDD anode and tungsten cathode
    Knichiro Yoshida, Mikito Ueda, Toshiaki Ohtsuka
    4th Asian conference on Molten salt chemistry and technology 394 - 395 2012年 [査読無し][通常論文]
  • Formation of Ag alloy particles in the glass by ion exchange treatment in molten salt
    Yuko Sakai, Mikito Ueda, Toshiaki Ohtsuka
    4th Asian conference on Molten salt chemistry and technology 364 - 365 2012年 [査読無し][通常論文]
  • 上田幹人, 林英樹, 大塚俊明
    Surface and coatings Technology 205 19 4401 - 4403 2011年06月 [査読有り][通常論文]
     
    To form Al-Pt alloys for high temperature coatings, molten salt electrolysis was attempted with an AlCl3NaCl-KCl molten salt containing PtCl2 at 448 K. The voltammogram showed cathodic reduction of Pt ions to start at a potential of 1.4 vs. Al/Al(III) in the molten salt. Deposition of pure Pt was possible at 1.2 V and there was co-deposition of Al and Pt at potentials more negative than 1.0 V. The co-deposit was a mixture of intermetallic compounds of AlPt2 or AlPt3. The ratio of the Pt in the electrodeposits decreased with increasingly negative potentials from 100 at.% at 1.2 V to 25 at.% at 0.0 V. (C) 2011 Elsevier B.V. All rights reserved.
  • Evaluation of NaTFSI -TEATFSI ionic liquid as an electrolytic melt for Na electrorefining
    Mikito Ueda, Kazuya Honda, Toshiaki Ohtsuka
    Proc. Electrochemical Society, Molten Salt 2534  2011年 [査読無し][通常論文]
  • Electrodeposition of Al-Sn alloys in AlCl3-NaCl-KCl molten salt containing SnCl2
    Mikito Ueda, Ryuichi, Toshiaki Ohtsuka
    International Symposium on Renewable Energy and Materials Tailoring 19  2011年 [査読無し][通常論文]
  • Electrorefining reaction of Na in TEATFSA-NaTFSA ionic liquid
    Mikito Ueda, Kazuya Honda, Toshiaki Ohtsuka
    International Symposium on Renewable Energy and Materials Tailoring 2011年 [査読無し][通常論文]
  • Development of Al-Cl2 battery in EMIC-AlCl3 ionic liquid
    Hajime Matsunaga, Mikito Ueda, Toshiaki Ohtsuka
    62nd Annual Meeting of International Society of Electrochemistry 2011年 [査読無し][通常論文]
  • Electroplating temperature for Al plating on Mg alloy in AlCl3-EMIC ionic liquid
    Shizuka Hariyama, Mikito Ueda, Toshiaki Ohtsuka
    62nd Annual Meeting of International Society of Electrochemistry 2011年 [査読無し][通常論文]
  • Oxygen reduction of Pd electrodes covered by platinum monolayers
    Toshiaki Ohtsuka, Yoshikazu Sugawara, Mikito Ueda
    62nd Annual Meeting of International Society of Electrochemistry 2011年 [査読無し][通常論文]
  • In situ observation of heterogeneity on thin titanium passive oxide film by micro-ellipsometry
    Atsushi Hyono, Kenji Yamanaka, Mikito Ueda
    62nd Annual Meeting of International Society of Electrochemistry 2011年 [査読無し][通常論文]
  • Diffusion of Tl ion into the glass by ion exchange treatment
    Mikito Ueda, H Matsunaga, Toshiaki Ohtsuka
    9th International symposium on Molten salt 101 - 106 2011年 [査読無し][通常論文]
  • Electroplating of aluminum alloys for improving oxidation resistance of TiAl intermetallics
    Mikito Ueda
    Proceedings of International conference on functional nanocoatings 27 - 28 2010年 [査読無し][通常論文]
  • Mikito Ueda, Yasushi Tabei, Toshiaki Ohtsuka
    MOLTEN SALTS AND IONIC LIQUIDS 17 33 7 563 - 570 2010年 [査読無し][通常論文]
     
    In order to improve the corrosion resistance of Mg and its alloys, Al layer was electrodeposited on their surface from aluminum chloride-1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3-EMIC). Mirror-like Al surface can be electroplated in AlCl3-EMIC ionic liquid by pulse electrolysis at 323 K, though Al layer was not dense and homogeneous. A dense and flat Al layer was successfully electroplated on Mg alloys in the AlCl3-EMIC ionic liquid at lower temperature of 283 K.
  • Formation of Nano-Particle in a Glass by Ion-Exchange Treatment
    Mikito Ueda, Yasushi Tabei, Toshiaki Ohtsuka, Toshiharu Yamashita
    The 12th International Symposium on Biomimetic Materials Processing 62  2010年 [査読無し][通常論文]
  • Mikito Ueda, Yasushi Tabei, Toshiaki Ohtsuka
    MOLTEN SALTS AND IONIC LIQUIDS 17 33 7 563 - 570 2010年 [査読無し][通常論文]
     
    In order to improve the corrosion resistance of Mg and its alloys, Al layer was electrodeposited on their surface from aluminum chloride-1-ethyl-3-methylimidazolium chloride ionic liquid (AlCl3-EMIC). Mirror-like Al surface can be electroplated in AlCl3-EMIC ionic liquid by pulse electrolysis at 323 K, though Al layer was not dense and homogeneous. A dense and flat Al layer was successfully electroplated on Mg alloys in the AlCl3-EMIC ionic liquid at lower temperature of 283 K.
  • 菊地竜也, 島口寛子, 上田幹人他
    表面技術 61 9 652 - 657 表面技術協会 2010年 [査読無し][通常論文]
     
    A printing plate for gravure printing consisting of five layers of aluminum alloy / anodic oxide film / nickel / polypyrrole / copper was fabricated by anodizing, electro-less plating, electroplating, and electro-polymerization. Nickel layers were first deposited on anodic oxide film-covered aluminum alloy by electro-less plating and electroplating. The polypyrrole layer was then deposited on the nickel layer by anodic polarization in a pyrrole monomer solution. Many copper fine particles were deposited on the polypyrrole-deposited specimen at the initial stage of electroplating in the CuSO4 / H2SO4 solution; then a continuous copper layer was obtained through longer cathodic polarization. The copper layer with polypyrrole was removed easily from the nickel layer by pulling with adhesive tape, which suggests that the structure is useful as a reusable aluminum printing plate by copper electroplating and electro-polymerization.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    JOURNAL OF MATERIALS CHEMISTRY 20 36 7630 - 7633 2010年 [査読有り][通常論文]
     
    The present work demonstrates a new approach to self-healing polymers that have the ability to repair artificial defects and restore the passive state of an underlying metal substrate. An intrinsically conducting polymer (ICP) with a well designed function of doped ions possesses specific permselective properties, restricting incorporation of aggressive chlorides from corrosive electrolyte. The cation permselective membrane controls the release of healing ions to the defect zone when artificial defects are formed, efficiently inhibiting corrosion of the underlying metal substrate.
  • 上田 幹人, 田 恵太, 大塚 俊明, 高橋 英徳
    日本金屬學會誌 73 10 773 - 777 日本金属学会 2009年10月 [査読無し][通常論文]
     
    To reduce Mg content in Al-Mg alloy for aluminum recycling, calcined powder made from used dry-cell battery was reacted with the liquid aluminum alloy. The powder was found to consist of ZnMn2O4, MnO, ZnO, and carbon by XRD analysis. After the reaction between pellets of the powder and the alloy in liquid at 973 K or 1073 K for 3.6 x 10(3) s, Mg content in the alloy decreased from 4.0 to 2.3 mass%. And at the same time, contents of Mn and Zn in the alloy increased from 0 to about 0.2 and 0.1 mass%, respectively. During the reaction, metallic Mg in the liquid Al-Mg alloy was found to move in to the pellets to form MgO. It may be assumed that an exchange reaction between Zn2+ at ZnO in the pellets and Mg2+ from the liquid alloy takes place.
  • 上田 幹人, 林 英樹, 大塚 俊明
    日本金屬學會誌 73 9 691 - 694 日本金属学会 2009年09月 [査読無し][通常論文]
     
    To develop a sodium electrorefining process for the recycling of used sodium-sulfur secondary battery, a non-aqueous electrolytic melt was investigated to pursue an efficient solvent and electrolyte for the process. Propylene carbonate containing NaPF6 was selected, since it has a wide potential window for electrochemical stability and a weak reactivity with metallic sodium. From the impedance measurement of propylene carbonate containing NaPF6, the maximum electric conductivity of 75 mS cm(-1) was found at concentration of 1 M NaPF6 at 338 K. The cathodic deposition of metallic sodium on a glassy carbon electrode and the anodic dissolution of metallic sodium occurred in the electrolytic melt. Sodium and a small amount of phosphorus were detected in the electrodeposit by ICP-AES analysis.
  • Yasushi Tabei, Mikito Ueda, Toshiaki Ohtsuka, Toshiharu Yamashita
    ELECTROCHEMISTRY 77 8 709 - 712 2009年08月 [査読無し][通常論文]
     
    To make functional glasses, ion-exchange treatment of the glass surface was carried out in TlNO3-NaNO3 molten salt at 673 K and 723 K for various time periods, and then the Tl ions embedded in the glass were reduced to metallic Tl nanoparticles by hydrogen gas. The color of the glass containing metallic Tl nanoparticles changed to brown or black. The Tl nanoparticles were detected by a qualitative TEM analysis. The optical absorption spectra of these treated glasses showed a peak at about 370 nm. With increases in the temperature of the molten salt, the band intensity of the absorption is enhanced. The absorption increase may correspond to larger particle sizes and densities with the increase in temperature. The Tl nanoparticles with 10-150 run diameter were observed at neighboring parts of the glass surface by TEM and FE-SEM.
  • Mikito Ueda, Shoh Tsuchiya, Toshiaki Ohtsuka
    ELECTROCHEMISTRY 77 8 659 - 662 2009年08月 [査読無し][通常論文]
     
    The electrodeposition of Sb-Bi-Te alloy in AlCl3-NaCl-KCl molten salt containing SbCl3, BiCl3, and TeCl4, at 423 K was carried out under constant potential control and potential pulse control in the melt. The electrodeposition results show that the SbCl3 concentration is effective to control the composition of Bi-Sb-Te ternary alloy. The electrodeposited Bi0.5Sb1.5Te3 by pulse electrolysis with frequency = 100 Hz and D. R. (Duty Ratio)= 75%, had good crystallinity and the preferential orientation of the electrodeposit was the (110) plane in this electrodeposition experiments. The electrodeposit had homogeneous disk-like granules. The power factor of the electrodeposit was calculated as 3 x 10(-5) Wm(-1) K-2 from the Seebeck coefficient and the electrical conductivity.
  • 上田 幹人, 宇井 幸一
    表面技術 = The journal of the Surface Finishing Society of Japan 60 8 491 - 496 一般社団法人 表面技術協会 2009年08月 [査読無し][招待有り]
  • Yuichi Tamura, Kento Taneda, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 51 7 1560 - 1564 2009年07月 [査読無し][通常論文]
     
    Effect of surface oxide on Pt-Co alloy electrodes on the oxygen reduction reaction (ORR) was investigated in 0.5 M sulfuric acid Solution by electrochemistry, ellipsometry. laser Raman scattering spectroscopy, and XPS. The oxide as thick as 1-2 nm increases the overpotential of ORR and falls down efficiency of PEFC. The thickness of the oxide films is precisely determined by ellipsometry. The oxide film 1.9 nm thick was formed on Pt-50 mol% Co electrode by constant potential oxidation at 1.20 V and the film 1.5 nm thick remains on the electrode at 0.6 V at which ORR already starts. The remaining oxide decreases the current density of ORR and increases the overpotential. On pure Pt electrode, the similar influence of the oxide filrn was observed. (C) 2008 Elsevier Ltd. All rights reserved.
  • Yusuke Mito, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 51 7 1540 - 1544 2009年07月 [査読無し][通常論文]
     
    Photo-luminescence emission was measured from the thin passive oxide him on nickel and chromium under the in-situ condition in 0.1 kmol m(-3) (M) sulfuric acid solution at pH 0.9 and neutral buffer solution of borate-boric acid mixture at pH 8.4 in order to obtain the insight of the electronic properties in the passive oxide film as thin as a few nm. The photo-luminescence induced by UV laser beam at 325 nm wavelength from nickel oxidized in both pH 0.9 sulfuric acid and pH 8.4 borate buffer solutions exhibited a broad spectrum feature with a peak at 400-420 nm. The energy of the peak wavelength from 400 to 420 nm is 2.95-3.10 eV which may correspond to the band-gap energy of the semiconduncting NiO. The photo-luminescence spectra from chromium oxidized in the sulfuric acid and neutral borate solutions had a peak at 400 nm and about 440 nm, respectively. These photo-emission from nickel and chromium oxidized is assumed to correspond to luminescence accompanied by recombination between excess electrons produced by UV light illumination in the conduction band and positive holes in the valence band. The broad tailing of the luminescence at longer wavelength side may represent high density of localized states originated in an amorphous nature of the passive oxides. (C) 2008 Elsevier Ltd. All rights reserved.
  • 菊地 竜也, 上田 晋吾, 上田 幹人, 坂入 正敏, 高橋 英明
    表面技術 = The journal of the Surface Finishing Society of Japan 60 5 335 - 341 表面技術協会 2009年05月01日 [査読無し][通常論文]
     
    Three-dimensional micro-actuators, consisting of a polypyrrole (PPy)/Au bi-layer, were fabricated by Al anodizing, laser irradiation, and electrochemical techniques. Aluminum specimens covered with porous type oxide films were irradiated with a pulsed Nd-YAG laser to locally remove the oxide films, and then an Au layer and a PPy layer were deposited at the area where the film had been removed. Finally, the specimens were immersed in a NaOH solution after connecting with/without a Pt plate to separate PPy/Au actuators from the Al substrate and anodic oxide film. The PPy layer didn’t lose its...
  • Na electrodeposition in propylene carbonate containing NaPF6, Proc. Electrochemical Society
    Mikito Ueda, Hideki Hayashi, Toshiaki Ohtsuka
    Organic electrochemistry 09 - 10 2009年 [査読無し][通常論文]
  • Mikito Ueda, Yusuke Mito, Toshiaki Ohtsuka
    MATERIALS TRANSACTIONS 49 8 1720 - 1722 2008年08月 [査読無し][通常論文]
     
    The Electrodeposition of Sb-Te alloy was carried Out in AlCl3-NaCl-KCl molten salt containing SbCl3 and TeCl4 at 423 K by constant potential electrolysis. The voltammogram on a glassy carbon (GC) electrode in a melt containing 1.0 X 10(-2) kmol m(-3) SbCl3 and 1.0 X 10(-2) kmol/m(3) TeCl4 revealed the cathodic current waves at 1.5, 1.1, and 0.9 V vs. Al/Al(III). A stable Sb-Te alloy deposit was obtained at 0.85 V in the melt containing SbCl3 and TeCl4. At the higher concentration ratio of the Sb(III) to (Sb(III) + Te(IV)). a good linear relation was found between the atomic ratio of Sb in the deposit and the concentration ratio of Sb (III) in the melt. The Sb-Te alloy deposit of atomic ratio of 38 : 62% which was assume to be suitable for a thermoelectric device was obtained with the molten salt containing 7.0 x 10(-3) kmol/m(3) SbCl3 and 1.0 x 10(-2) kmol/m(3) TeCl4. The XRD pattern of the deposit corresponds to that of Sb2Te3 intermetallic compound. The deposit had homogeneous disk-like granule with the disk size of about 10 mu m..
  • Mikito Ueda, Yusuke Mito, Toshiaki Ohtsuka
    MATERIALS TRANSACTIONS 49 8 1720 - 1722 2008年08月 [査読無し][通常論文]
     
    The Electrodeposition of Sb-Te alloy was carried Out in AlCl3-NaCl-KCl molten salt containing SbCl3 and TeCl4 at 423 K by constant potential electrolysis. The voltammogram on a glassy carbon (GC) electrode in a melt containing 1.0 X 10(-2) kmol m(-3) SbCl3 and 1.0 X 10(-2) kmol/m(3) TeCl4 revealed the cathodic current waves at 1.5, 1.1, and 0.9 V vs. Al/Al(III). A stable Sb-Te alloy deposit was obtained at 0.85 V in the melt containing SbCl3 and TeCl4. At the higher concentration ratio of the Sb(III) to (Sb(III) + Te(IV)). a good linear relation was found between the atomic ratio of Sb in the deposit and the concentration ratio of Sb (III) in the melt. The Sb-Te alloy deposit of atomic ratio of 38 : 62% which was assume to be suitable for a thermoelectric device was obtained with the molten salt containing 7.0 x 10(-3) kmol/m(3) SbCl3 and 1.0 x 10(-2) kmol/m(3) TeCl4. The XRD pattern of the deposit corresponds to that of Sb2Te3 intermetallic compound. The deposit had homogeneous disk-like granule with the disk size of about 10 mu m..
  • Electrodeposition of Bi-Sb-Te alloys in molten salt
    Mikito Ueda, Syou Tstushiya, Toshiaki Ohtsuka
    8th International Symposium on Molten Salts 445 - 450 2008年 [査読無し][通常論文]
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 50 1 286 - 291 2008年01月 [査読無し][通常論文]
     
    Ultrasonic irradiation was imposed during electropolymerization of polypyrrole (PPy) in acid phosphate solution containing molyb-dophosphate (PMo12O403-) ions and pyrrole monomer. Corrosion of the steel coated by the PPy film prepared under ultrasonic irradiation was tested in 3.5 wt.% NaCl solution and compared with corrosion of the steel coated by the PPy film without ultrasonic irradiation. The PPy film prepared under ultrasonic irradiation kept the steel in the passive state one and a half times as long as that prepared without ultrasonic irradiation. Imposition of ultrasound enhanced the doping of PMo12O403-. and decreased the doping of HPO42-. The surface morphology of the PPy film was changed with imposition of ultrasound in electropolymerization process. Under imposition of ultrasound, a dense and compact PPy layer was formed. The structure of the PPy film obtained under ultrasonic irradiation was assumed to result from change in nucleation-growth mechanism. (c) 2007 Elsevier Ltd. All rights reserved.
  • M. Ueda, T. Ohtsuka, K. Kuroda, R. Ichino, M. Okido
    TRANSACTIONS OF THE MATERIALS RESEARCH SOCIETY OF JAPAN, VOL 33, NO 3 33 3 779 - 782 2008年 [査読無し][通常論文]
     
    For application of Ti to the bio-implant materials, the anodic etching of Ti in the molten salt of LiCl-KCl and EMIC-AlCl(3) was investigated. The roughness of the Ti surface after the etching was examined from the SEM observation. The etching of the Ti electrode in the melt of LiCl-KCl did not form a Suitably rough Surface morphology. In the melt, the largely rough surface was formed with top-to-bottom distance of 10 mu m. The etching in the melt of EMCI-AlCl(3) at the potential of 0.6 V vs. Al/Al(III) introduced the formation of a rough Surface applicable to the Ti implant. The rough surface formed in the melt exhibits the top-to bottom distance of about 1 mu m.
  • Y. Tamura, K. Taneda, M. Ueda, T. Ohtsuka
    PROTON EXCHANGE MEMBRANE FUEL CELLS 8, PTS 1 AND 2 16 2 741 - 750 2008年 [査読無し][通常論文]
     
    PtCo and PdCo alloy electrodes were investigated in a 0.5 M sulfuric acid solution by electrochemistry, ellipsometry, laser Raman scattering spectroscopy, XPS, and GD-OES. The corrosion resistibility of Pt-Co and Pd-Co alloys decreased with increase of Co addition. The increase of Co addition, however, enhanced the catalytic efficiency on the ORR. The alloy surfaces may be covered by CoOOH and Pt or Pd oxide 2-3nm thick. At the potential of 1.2V vs. Ag/ AgCl/ sat. KCl, the thickness of oxide film increased with the Co addition. The presence of the oxide film on the alloy electrodes increases the overvoltage for the ORR. The effect of the oxide thickness on the ORR was discussed.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    ECS Transactions 16 52 177 - 182 2008年 [査読無し][通常論文]
     
    A bi-layered PPy film consisting of an inner layer doped with Keggin-structure anions of PMo12O403- and HPO42- (PPy-PMo12) and an outer layer doped with organic anions of dodecyl sulfate (PPy-DoS) exhibited a self-healing property when coated on steel. When a defect was introduced into the PPy-coated steel immersed in 3.5% NaCl aqueous solution, the potential initially decreased and activation of the coated steel occurred. After a few hours, the potential was recovered to the passive region, and the passivation continued for another 20 hours. Without any damage, the release of PMo12 doped in the inner layer was inhibited by the outer PPy layer doped with DoS. When a defect was introduced into the PPy film, the inner PPy layer released phosphate and molybdate anions to the damaged zone due to their decomposition via hydrolysis. Both anions work as passivation inhibitors and helped to repassivate the damaged zone on the steel. ©The Electrochemical Society.
  • Hirofumi Ebe, Mikito Ueda, Toshiaki Ohtsuka
    ELECTROCHIMICA ACTA 53 1 100 - 105 2007年11月 [査読無し][通常論文]
     
    The Electrochemistry of Sb, Bi, and Te in AlCl3-NaCl-KCl molten salt containing SbCl3, BiCl3, and/or TeCl4 at 423 K was investigated by voltammetry, and electrodeposition of the three metals was performed under constant potential control in the melt. The voltammogram on a glassy carbon (GC) electrode in a melt containing 0.025 mol dm(-3) [M] SbCl3 showed a couple of redox peak corresponding to the Sb/Sb(III) redox reaction, and a stable layer of pure Sb was deposited under the constant potential control. The voltammograms in the melt containing 0.025 M BiCl3 or 0.025 M TeCl4 showed several redox couples. Stable deposit layers of pure Bi and Te were not obtained under the constant potential control, as the deposited layers detached from the electrode and immediately dissolved into the molten salt. Binary alloy deposition was possible in a melt containing BiCl3 and SbCl3, and also with BiCl3 and TeCl4. A stable Bi-Sb alloy deposit of metallic Sb and Bi-Sb solid solution was obtained at 0.8 and 0.9 V versus Al/Al(III) in the melt containing BiCl3 and SbCl3. The atomic ratio of Bi in the deposit was 37% at 0.9 V and 57% at 0.8 V. A stable Bi-Te alloy deposit was also obtained with the molten salt containing BiCl3 and TeCl4. The deposited Bi-Te alloy consisted of a mixture of Bi2Te3, BiTe, and Bi2Te. The alloy deposit had good crystallinity and the preferential orientation was the (I 10) plane. (C) 2007 Elsevier Ltd. All rights reserved.
  • 上田 幹人, 劉 博, 大塚 俊明, 高橋 英徳
    日本金屬學會誌 = Journal of the Japan Institute of Metals 71 11 1046 - 1049 日本金属学会 2007年11月 [査読無し][通常論文]
     
    A composite oxide produced from used dry battery was used to decrease Mg content in Al-Alg alloy at high temperature. The oxide was found to consist of ZnMn2O4, ZnMnO3, and ZnO by XRD analysis. After a reaction between a pellet made from the oxide powder and the alloy in liquid at 973 K for 2 h, Mg content in the alloy decreased from 4.0 to 3.6 mass%. During the reaction, metallic Mg probably diffused into the pellet to form MgMn2O4 and then exchanged with Zn(II) in ZnMn2O4.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 49 8 3442 - 3452 2007年08月 [査読無し][通常論文]
     
    The bi-layered polypyrrole (PPy) coatings were investigated for corrosion prevention of a carbon F steel. The inner layer was doped with the Keggin structure anions Of PMO12O403- (PMO12) and HpO(4)(2-) anions for stabilization of the passive oxide film at the metal-polymer interface, and the outer layer was doped with four organic anions of dihydroxynaphthalenedisulfonate (DHNDS), naphthalenedisulfonate (NDS), anthraquinonedisulfonate (AnqDS) or dodecylsulfate (DoS) for inhibition of the decomposition and release of PMo12. The corrosion tests were performed in 3.5 wt.% NaCl aqueous solution. The corrosion resistance of the steels covered by the bi-layered PPy films was found in the following order: PPY-PMo12/PPy-DHNDS < PPY-PMo12/PPy-NDS < PPY-PMo12/AnqDS < Ilk PPY-PMO12/PPy-DoS. The performance of corrosion protection related to the oxidized state of the polymer was discussed. (c) 2007 Elsevier Ltd. All rights reserved.
  • Damian Kowalski, Mikito Ueda, Toshiaki Ohtsuka
    CORROSION SCIENCE 49 3 1635 - 1644 2007年03月 [査読無し][通常論文]
     
    Bi-layered polypyrrole (PPy) coating was investigated for corrosion prevention of steels. The PPy coating consisted of the inner layer doped with PMo12 40 (PMo12) and HPO42- ions and the outer layer doped with naphthalenedisulfonate (NDS) ions. PMo12 ions doped in the inner layer make the passive oxide film on steel stabilized and the outer layer doped with large organic ions of NDS restricts decomposition and release of PMo12 ions in the inner layer. Corrosion tests were made in 3.5% NaCl aqueous solution for the steels covered by the single PPy-PMo12, single PPy-NDS, and bi-layered PPy-PMo12/PPy-NDS coatings. The single PPy-PMo12 and PPy-NDS coatings maintained the steel in passive state for 34h and 24h, respectively. The bi-layered coating kept the steel in passive state and prevented corrosion of the steels for the longer time period. (c) 2006 Elsevier Ltd. All rights reserved.
  • T. Kikuchi, Y. Akiyama, A. Ueda, A. Sakairi, H. Takahashi
    ELECTROCHIMICA ACTA 52 13 4480 - 4486 2007年03月 [査読無し][通常論文]
     
    Ribbon type and three-dimensional micro-actuators, consisting of three-layer structure of acrylic acid resin/Au/polypyrrole, were fabricated by aluminum anodizing, laser irradiation, and electrochemical techniques, and their performance was examined. Anodized aluminum specimens were irradiated with a pulsed Nd-YAG laser to remove anodic oxide films locally, and then an An layer was deposited at the area where film had been removed. The subsequent electrophoretic deposition of acrylic acid resin on the An layer, dissolution of anodic oxide film and the metal substrate, and deposition of polypyrrole on backside of An layer by electro-polymerization enabled the fabrication of a three-layer actuator. Cyclic voltammetry of the ribbon type actuator in different electrolyte solutions showed that redox reactions of polypyrrole is accompanied with doping and dedoping of hydrated cations, and that the redox reaction strongly depends on the valency of cations in the solutions. The three-dimensional micro-actuator showed good performance as a manipulator, gripping and moving objects of several milligram in solutions. (c) 2007 Elsevier Ltd. All rights reserved.
  • Mikito Ueda, Hirokuni Kigawa, Toshiaki Ohtsuka
    ELECTROCHIMICA ACTA 52 7 2515 - 2519 2007年02月 [査読無し][通常論文]
     
    To improve the oxidation resistance of TiAl intermetallic compound under high temperature condition, cathodic co-deposition of Al-Cr and Al-Ni alloy was carried out by constant potential control or potential pulse control in AlCl3-NaCl-KCl molten salt containing CrCl2 and/or NiCl2 at 423 K. Cathodic reduction of Ni and Cr starts at potential of 0.8 and 0.15 V versus Al/Al3+ in the molten salt, respectively. The co-deposition of At, Cr, and Ni occurred at potentials more negative than -0.1 V to form a mixture of intermetallic compounds of Cr2Al, Ni3Al, and Al3Ni. Concentration of Cr in the deposit was enhanced to 43 at% at -0.1 V; however, concentration of Ni in the deposit was 6 at% at the same potential. The concentration of Ni further decreased with more negative potential to 1 at% at -0.4 V. The potential pulse technique enhanced the Ni concentration in the deposit to about 30 at%, due to anodic dissolution of Al content from the deposit at the higher side of potential on the potential pulse electrolysis. (c) 2006 Elsevier Ltd. All rights reserved.
  • Silvio Koehler, Mikito Ueda, Igor Efimov, Andreas Bund
    ELECTROCHIMICA ACTA 52 9 3040 - 3046 2007年02月 [査読無し][通常論文]
     
    The potentiostatic deposition of polypyrrole (PPy) from 0.1 M aqueous phosphoric acid solution and the doping/dedoping behavior of the resulting films have been investigated by the electrochemical quartz crystal microbalance (EQCM) technique. The change of the complex shear modulus during the film growth and during the doping/dedoping were calculated using the acoustic impedance method. It was found that the films contain only ca. 1 wt% water in the oxidized state which is in accordance with their relatively high storage modulus of 38 MPa and low loss tangent of 0.05. Comparing H3PO4 (pH 1) and NaH2PO4 (pH 8) it was found that the doping/dedoping in the latter is accompanied by a strong increase of the surface roughness which is a direct result of cation exchange present at pH 8. (c) 2006 Elsevier Ltd. All rights reserved.
  • Anodic Dissolution of Ti in EMIC-AlCl3 Ionic Liquid or LiCl-KCl Molten Salt for Enhancement of Adhesion Between Coating Layer and Ti Substrate
    Mikito Ueda, Toshiaki Ohtsuka, Kensuke Kuroda, Ryoichi Ichino, Masazumi Okido
    Biodegradability and toxicity of ionic liquids meeting 16  2007年 [査読無し][通常論文]
  • Sho Tsuchiya, Mikito Ueda, Toshiaki Ohtsuka
    ISIJ INTERNATIONAL 47 1 151 - 156 2007年 [査読無し][通常論文]
     
    The polypyrrole (PPy) coating was prepared by constant current oxidation on zinc from aqueous solution of sodium tartrate containing sodium molybdate and pyrrole monomer to make new coating for corrosion prevention of zinc-coated steels. The coating is started with an initial formation of salt layer of zinc tartrate and/nor zinc molybdate during the oxidation. Nucleation and growth of PPy take place on the salt layer in the second stage. The PPy layer thus formed is doped by tartrate ions and/nor molybdate ions, which was confirmed by a depth profile measurement of glow discharge optical emission spectroscopy (GD-OES). The conductance of the coatings was as small as 1 x 10(-3) S cm(-2) for the 5 mu m-thick layer probably due to the formation of the salt layer underneath the PPy layer. Corrosion test of the PPy-coated zinc electrode in 3.5wt% NaCl solution showed that the zinc electrode was passivated and protected over 48 h by action of the oxidative PPy coating doped by tartrate and molybdate ions.
  • H. Hosoya, M. Arita, K. Hamada, Y. Takahashi, K. Higashi, K. Oda, M. Ueda
    JOURNAL OF PHYSICS D-APPLIED PHYSICS 39 24 5103 - 5108 2006年12月 [査読無し][通常論文]
     
    We investigate composite Fe-SrF2 films to explore new materials showing the granular-type tunnelling magnetoresistance (TMR) effect. The films are composed of Fe nano-particles embedded in a SrF2 matrix. The electromagnetic properties of the ferromagnetic metal-insulator films are confirmed, including super-paramagnetism, tunnel conduction and TMR. We obtain a TMR of 3% at RT and 5% at 77 K. The film resistivity is much higher than that of oxide-based granular film. We also fabricate the nanostructures of granular films and aim at the application of the single-electron transistor. As a result, we observed a Coulomb blockade (CB) region and CB oscillation at low temperature.
  • T Ohtsuka, M Iida, M Ueda
    JOURNAL OF SOLID STATE ELECTROCHEMISTRY 10 9 714 - 720 2006年09月 [査読無し][通常論文]
     
    The polypyrrole coating was prepared from phosphoric acid aqueous solution containing the hetero-polyanion PMo12O403- and pyrrole monomer to make new coating for corrosion prevention of carbon steels. The coating thus formed in the phosphate acid solution was doped by PMo12O403- and by PO43-. The coating was flexible enough to cover the steel homogeneously without cracks, although many cracks were observed on the coating formed in a neutral aqueous solution of Na2MoO2. The 5.1-mu m-thick polypyrrole coating makes the steel maintain the passive state for 48 h in neutral 3.5 wt% NaCl solution at pH 5.3 and for 80 h in acidic 3.5 wt% NaCl solution at pH 1.9. The coating decreased the corrosion rate of the steel by 1/200 in the neutral NaCl solution and by 1/340 in the acidic NaCl solution, if compared with the rate of the bare steel. The dissolution current of the steel during the immersion remained at the level of the typical passive current in the respective solutions.
  • Y Akiyama, T Kikuchi, M Ueda, M Iida, M Sakairi, H Takahashi
    ELECTROCHIMICA ACTA 51 23 4834 - 4840 2006年06月 [査読無し][通常論文]
     
    Polypyrrole was deposited at selected areas on aluminum by anodizing, laser irradiation, and electrolytic polymerization, and the application of the technique for fabricating micro-actuators was attempted. Aluminum specimens covered with porous type anodic oxide films were irradiated with a pulsed Nd-YAG laser to remove the oxide films locally, and then thin Ni layers were deposited at areas where film had been removed. Polypyrrole could be successfully deposited only on the Ni layer by anodic polarization of the specimens in pyrrole monomer solution, and a polypyrrole/Ni bilayer structure could be obtained by dissolution of the aluminum substrate and anodic oxide film in NaOH solutions. The bilayer structure was found to be inactive to doping and dedoping of ions during anodic and cathodic polarization. A three-layer structure, nitrocellulose/Ni/polypyrrole, fabricated by electrolytic polymerization after nitrocellulose coating on a Ni layer detached from the aluminum substrate, showed ion-doping and -dedoping activity, suggesting the possibility of fabricating micro-actuators in this manner. (c) 2006 Elsevier Ltd. All rights reserved.
  • M Ueda, Y Abe, T Ohtsuka
    MATERIALS LETTERS 60 5 635 - 638 2006年03月 [査読無し][通常論文]
     
    Direct reduction from SiO2 to metallic Si by aluminum metal fog was attempted in NaCl-KCl molten salt. The aluminum metal fog was evolved by contact of liquid aluminum metal to Al(III) in the molten salt. The metal fog forms in the molten salt an atmosphere reductive enough to induce a reaction from SiO2 to Si. The immersion of SiO2 plate at the aluminum metal fog in the molten salt caused the color change of the plate, and the plate exhibited the darker color with time. From EPMA and XRD analysis, metallic crystallized Si was detected in the darkened area. From the color change with time, the reaction proceeding was discussed. (c) 2005 Elsevier B.V. All rights reserved.
  • Co-deposition of Al-Cr-Ni Alloys Using Constant Potential and Potential Pulse Technique in AlCl3-NaCl-KCl Molten Salt
    Mikito Ueda, Hirokuni Kigawa, Toshiaki Ohtsuka
    4th Spring Meeting of International Society of Electrochemistry 20 - 21 2006年 [査読無し][招待有り]
  • M Ueda, S Tsukamoto, S Konda, T Ohtsuka
    JOURNAL OF APPLIED ELECTROCHEMISTRY 35 9 925 - 930 2005年09月 [査読無し][通常論文]
     
    To recover aluminum from aluminum dross, a floating separation of aluminum alloy from the oxides and subsequent electrolysis of the oxides was carried out in a molten salt bath of 33 mol% AlF3, 51 mol% NaF and 16 mol% BaCl2. With A356.0 casting alloy dross, 83% of the aluminum alloy was recovered by the floating separation. A further 4% of metallic aluminum was recovered by electrolysis in the molten salt containing the oxides separated from the dross. The optimum current for continuous operation is discussed considering a balance between the electrowinning and dissolution rates.
  • M Ueda, H Ebe, T Ohtsuka
    ELECTROCHEMISTRY 73 8 739 - 741 2005年08月 [査読無し][通常論文]
     
    To improve the oxidation resistance of TiAl intermetallic compounds under high temperature conditions, electrodeposition of an Al, Cr, and Ni layer was carried out by constant potential control or potential pulse control in AlCl3-EMIC (1-ethyl-3-methyl-imidazolium chloride) ambient-temperature molten salt containing NiCl2 and CrCl2 at 338 K. The electrodeposition of Al, Cr, and Ni occurred at potentials lower than 0.0 V vs. Al/Al3+. Ni concentration in the deposit was about 9 at% at 0 V. However, it decreased with a decrease in potential to 1 at% at -0.2 V. The potential pulse technique enhanced the Ni concentration in the deposit to 20-27 at%. Cr concentration was also enhanced by pulse potential control: the concentration of Cr was raised to 15 at%. In all electrodeposits, sharp peaks corresponding to Al metal were detected with a relatively high background by XRD, analysis. It is conceivable that deposit layers consisting of Al, Cr, and Ni may be amorphous.
  • 佐藤 忠夫, 上田 幹人, 佐伯 功
    電気化学および工業物理化学 : denki kagaku 73 8 736 - 738 電気化学会 2005年08月 [査読無し][通常論文]
     
    Limiting current densities of silver deposition in AlCl3-NaCl-AgCl or LiCl-KCl-AgCl melts, and change in the equilibrium potential of silver with AlCl3 concentration were measured to consider a large potential difference in the two melts. Diffusion rate of silver species in AlCl3-NaCl-AgCl melt was concluded to be much slower than that in LiCl-KCl-AgCl melt. The formation of a silver complex in AICl(3)-NaCI-AgCl melt was suggested. The equation, Ag + AlCl4- = AgAlCl4 + e or Ag + 2 AlCl4- =Ag(AlCl4)(2-) + e., might be a possible electrochemical reaction of silver in the melt.
  • Reduction of SiO2 to Si by Aluminum particles in NaCl-KCl-AlCl3 Molten Salt
    Mikito Ueda, Yoshihisa Abe, Toshiaki Ohtsuka
    7th International Symposium on Molten Salt 247 - 249 2005年 [査読無し][通常論文]
  • Co-deposition of Al-Cr-Ni alloy using a pulse electrolysis in AlCl3-EMIC molten salt
    Mikito Ueda, Hirofumi Ebe, Toshiaki Ohtsuka
    1st congress of international ionic liquid 121 - 122 2005年 [査読無し][通常論文]
  • Atmospheric Corrosion of Zinc and Zinc Alloy Using In-situ Raman Spectroscopy
    Mikito Ueda, Masaru Matsuda, Toshiaki Ohtsuka
    Proc. Electrochemical Society meeting, Atmospheric corrosion 215 - 219 2004年 [査読無し][通常論文]
  • Co-deposition of Al-Cr and Al-Ni Alloys Using Potential Pulse Technique in Molten Salt
    Mikito Ueda, Hirokuni Kigawa, Toshiaki Ohtsuka
    The 14th International Symposium on Molten Salt 2459  2004年 [査読無し][通常論文]
  • Atmospheric Corrosion of Zinc and Zinc Alloy Using In-situ Raman Spectroscopy
    Mikito Ueda, Masaru Matsuda, Toshiaki Ohtsuka
    Proc. Electrochem. Soc. Meeting 765  2004年 [査読無し][通常論文]
  • Corrosion Products on Zinc-coated Steels Detected by in-situ Raman Spectroscopy
    Mikito Ueda, Masaru Matsuda, Toshiaki Ohtsuka
    Galvatech ’04 Conference Proceedings 845 - 852 2004年 [査読無し][通常論文]
  • M Ueda, D Susukida, S Konda, T Ohtsuka
    SURFACE & COATINGS TECHNOLOGY 176 2 202 - 208 2004年01月 [査読無し][通常論文]
     
    For improvement of the oxidation resistance of a TiAl alloy under high temperature conditions, aluminum chromium alloys were electroplated on the TiAl alloy in an AlCl3-NaCl-KCl molten salt containing CrCl2 at 423 K. The deposit electroplated at -0.1 V vs. Al/Al3+ consists of gamma-Al8Cr5 single phase, including chromium content at 41 at.%. A mixture phase of gamma-Al8Cr5 and Al is, however, formed at potential from - 0.2 to - 0.4 V. The oxidation resistance of the electrodeposit layer was evaluated by a high temperature oxidation test at 1173 K for 24 h. On the TiAl specimen covered with gamma-Al8Cr5 which was deposited at -0.1 V, a uniform AlCr2 layer was formed during the oxidation at 1173 K. The AlCr2 layer was covered by a thin dense Al2O3. Both AlCr2 and Al2O3 layers play a role of superior protection from the high temperature oxidation of the TiAl alloy; therefore, the plating of the gamma-Al8Cr5 single layer deposited at -0.1 V reduced oxide thickness by 1/40 during the oxidation at 1173 K for 24 h from that on the TiAl without any plating. (C) 2003 Elsevier Science B.V. All rights reserved.
  • 宇井 幸一, 上田 幹人, 萩原 理加
    溶融塩および高温化学 47 3 114 - 123 電気化学会溶融塩委員会 2004年 [査読無し][通常論文]
  • 上田 幹人, 薄田 大吾, 近田 昭一, 大塚 俊明
    表面技術 = The Journal of the Surface Finishing Society of Japan 54 5 363 - 366 一般社団法人 表面技術協会 2003年05月01日 [査読無し][通常論文]
     
    Anodic stripping of TiAl surface was carried out in AlCl3-NaCl-KCl molten salt at 423 K as a pretreatment for the deposit formation of an Al-Cr alloy layer. The Al-Cr alloy deposit on the TiAl significantly improved the corrosion resistance against high temperature oxidation. In anodic stripping at 0.4 V vs. Al/Al3+, anodic dissolution of surface occurred non-uniformly. On the other hand, an oxide film on TiAl was completely removed by uniform anodic dissolution at 1.2 V with electricity of 1 C cm-2. An Al-Cr electroplating layer that was formed after the anodic stripping at 1.2 V, exhibite...
  • Photoluminescence of Ti Oxide Film in Phosphate, Sulfate, and Chloride Solution
    Mikito Ueda, Toshiaki Ohtsuka
    Proceedings of the 13th Asian-Pacific Corrosion Control Conference F-07  2003年 [査読無し][通常論文]
  • 道明 誉裕, 上田 幹人, 大塚 俊明
    材料と環境 : zairyo-to-kankyo 52 8 421 - 427 腐食防食協会 2003年 [査読無し][通常論文]
     
    Conductive polymer film of polypyrrole (PPy) doped by polymolybdate (PMo) anions was prepared on mild steels by anodic polymerization for corrosion prevention of the steels. The PPy-PMo conductive film prepared exhibits good adherence to the steel substrate. The mass and thickness of the PPy-PMo film linearly increase with electricity during constant current polymerization at 5 mA·cm-2. The density of the PPy-PMo polymer film was evaluated to be 2.5 g·cm-3 from the ratio of the mass to thickness. A corrosion test in neutral and acidic 3.5 wt% NaCl solutions was done for the steels covered by the PPy-PMo film. Corrosion of the steels is suppressed by the films: the corrosion rate in the neutral solution decreases by 1/3 compared with that of the bare steel and the rate in the acidic solution by 1/4. The film was gradually reduced during immersion in the solutions with progress of the corrosion reaction of Fe dissolution to Fe2+, which is accompanied with the dissolution from PMo in the film to MoO4 2- in the neutral solution, or with pickup of protons and sodium ions in the acidic solution.
  • M Ueda, H Dietz, A Anders, H Kneppe, A Meixner, W Plieth
    ELECTROCHIMICA ACTA 48 4 377 - 386 2002年12月 [査読無し][通常論文]
     
    Various structures of silver nanoparticles were generated by means of the double-pulse technique. The interaction of the pulse parameters was modeled to demonstrate that the electrodeposition of nanoparticles can be variably controlled. The results derived showed how to create nanoparticle structures with respect to size, density and monodispersity according to the application goal. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • M Ueda, T Ohtsuka
    CORROSION SCIENCE 44 7 1633 - 1638 2002年07月 [査読無し][通常論文]
     
    Luminescence light from the anodic thin oxide films formed on titanium in neutral phosphate solution was measured by photo-excitation of ultra-violet light irradiation with 3.82 eV energy. The luminescence light is observed with a peak of about 3 eV energy that corresponds to the band-gap energy of the n-type semiconductive TiO2 oxide. It can therefore be presumed that the luminescence is induced by de-excitation or recombination between electrons in the conduction band and holes in the valence band. The peak wavelength of the luminescence light changes with the formation potential of the oxide film from 409 nm at 1 V to 425 nm at 6 V. The shift of the peak may reflect an amorphous-crystalline transition with increase of potential. (C) 2002 Elsevier Science Ltd. All rights reserved.
  • M Ueda, D Susukida, S Konda, T Ohtsuka
    MOLTEN SALTS XIII 2002 19 724 - 733 2002年 [査読有り][通常論文]
     
    Al-Cr alloys were electroplated on the TiAl alloy in an AlCl3-NaCl-KCl molten salt containing CrCl2 at 423 K. The deposit consisting of gamma-Al8Cr5 single phase is obtained at potential of -0.1 V vs. Al/Al3+ and includes chromium content at 41 at%. The gamma-Al8Cr5 and Al mixture phase is, however, formed at potential from -0.2 to -0.4 V. The oxidation resistance of the electrodeposit was evaluated by a high temperature oxidation test at 1173 K for 24 h. The TiAl specimen with the Al-Cr deposit formed at -0.1 V is covered by the Cr2Al uniform layer and the thin dense Al2O3 layer after oxidation. For the TiAl specimen with the deposits formed from -0.2 to -0.4 V, however, the uniform protective layer does not form. The plating of the gamma-Al8Cr5 single phase deposit is found to reduce the oxide formation by 1/40 in thickness from that on the TiAl without the Al-Cr deposit by the oxidation.
  • M Ueda, T Ohmura, S Konda, T Sasaki, T Ohtsuka, T Ishikawa
    JOURNAL OF APPLIED ELECTROCHEMISTRY 31 8 871 - 875 2001年08月 [査読無し][通常論文]
     
    Electrorefining of aluminium was carried out at 750 degreesC using bipolar electrode cells with centre holes 2, 10 or 20 mm in diameter. Through the centre holes liquid electrorefined aluminium rises to the electrolyte surface. The bipolar electrode cell consists of graphite cathodes, Al-Cu-Fe-Mn or Al-Cu-Fe-Zn alloy anodes and a BaCl2-NaCl-AlF3-NaF electrolytic melt. The centre hole size of more 20 mm in diameter is required to continuously float up the aluminium electrodeposited onto the electrolyte surface, while the current efficiency of the cell decreases with increase of the centre hole size, from 97% at 2 mm diameter to 92% at 20 mm diameter. Aluminium of 99.97% purity precipitates at the cathode. Iron, manganese and zinc included in the alloy as impurities are hardly deposited and the concentrations of these elements in the deposit are 100, 80 and 170 ppm, respectively. In this process aluminium can be produced with an energy consumption of about 4.9 x 10(3) kWh(t-Al)(-1), which is one-third smaller than that of the Gadeau process.
  • Luminescence with Band-Gap Energy by UV-Light Excitation to Anodic Oxide Films on Titanium
    Mikito Ueda, Toshiaki Ohtsuka
    Proc. the 2nd Intern. Conf. on Environment Sensitive Cracking and Corrosion Damage 43 - 45 2001年 [査読無し][通常論文]
  • 佐藤 忠夫, 堀米 毅, 上田 幹人
    表面技術 = The Journal of the Surface Finishing Society of Japan 51 6 640 - 645 一般社団法人 表面技術協会 2000年06月01日 [査読無し][通常論文]
     
    TiB2 and TiN films were coated by chemical vapor deposition on SKD 61 steel to improve the corrosion resistivity of a diecasting machine in a melted aluminum alloy. The protectivity of the film in the melted aluminum alloy was examined by an immersion test at 900°C and a thermal cycle test between room temperature and 900°C. TiN film, which serves as a binder, greatly improves the adhesion of TiB2 film on the steel substrate. The thermal cycle test indicated that the optimum thickness of TiB2 and TiN layers is at 4 and 6μm, respectively. Compared to ion-nitrized steel, steel coated by TiB2/...
  • 上田 幹人
    溶融塩および高温化学 43 3 177 - 185 電気化学協会溶融塩委員会 2000年 [査読無し][通常論文]
  • M Ueda, T Ohmura, S Konda, T Sasaki, T Ohtsuka
    MOLTEN SALTS XII, PROCEEDINGS 99 41 723 - 731 2000年 [査読有り][通常論文]
     
    Electrorefining of aluminum was carried out at 750 degrees C by using a bipolar cell which has center holes with size 2, 10 or 20mm for easy upward flowing of the molten aluminum. The bipolar cell consists of graphite cathodes, Al-Cu-Fe-Mn or Al-Cu-Fe-Zn alloy anodes and BaCl2-NaCl-AlF3-NaF electrolytic melt. The efficiency of the cell is influenced by the center hole size: when the size of center holes increases, the efficiency decreases. However, a center hole size over 20mm diameter is required in order to allow a continuous flow electrodeposited aluminum on to the electrolytic melt surface. After electrolysis, it is found that very pure aluminum with 99.97% deposits on the cathode. Manganese and zinc dissolving from the anode alloy into the electrolytic melt hardly deposit on the cathode in the electrorefining process. Aluminum can be produced with energy consumption below 5,000kWh/t-Al with this process.
  • M Ueda, K Imasawa, S Konda, T Sasaki, T Ishikawa, T Ohtsuka
    ELECTROCHEMISTRY 67 6 695 - 699 1999年06月 [査読無し][通常論文]
     
    To decrease the reaction polarization of the cathodic reaction of Cl-2 +2e(-) --> 2Cl(-) in Al-Cl-2 electrochemical cell in NaCl-KCl melt at 1023 K, we developed a cell system with a vertically rotating electrode composed of sliced graphite disks which are partially immersed in the melt. The apparent reaction resistance of the cathodic reaction was evaluated from transient potential and current changes of the cell. The reaction resistance decreases with an increase of the number of the graphite disks. The resistance is a function of the rotation rate of the electrode and exhibits the minimum Value around a rotation rate of 20 rpm. The dependence on the rotation rate may be explained from Cl-2 concentration in a thin melt layer formed on the graphite electrode during exposure to Cl-2 gas phase. The rotation may introduce a continuous supply of the thin melt layer with a high concentration of Cl-2 to a reaction place at a meniscus part on the graphite electrode. However, if the rotation rate is too high, the exposure time of the thin melt layer to Cl-2 gas is not enough to establish an equilibrium concentration of Cl-2 in the layer.
  • 上田 幹人, 雨宮 睦仁, 石川 達雄, 大塚 俊明
    日本金屬學會誌 63 3 279 - 283 日本金属学会 1999年03月 [査読無し][通常論文]
     
    A new process for recovery of aluminum from aluminum dress was developed. The aluminum dress which is obtained as a by-product during casting process of aluminum alloy contains aluminum alloy and oxides of various metals including aluminum oxide. The process consists of two stages: (1) Separation of the aluminum alloy from the oxides by difference in density between the alloy and the oxide in molten salts. (2) Dissolution of oxides into molten salts, and electrolysis of the molten salts to form metallic aluminum from the oxide. This paper is concerned with the first stage for the separation of the aluminum alloy from the oxides by using BaCl2-NaCl-NaF melts. The aluminum alloy completely separates from the oxides in the melts at concentrations of BaCl2 higher than 33.3 mol%, in which the liquid aluminum alloy floats up and the oxides sink down. From a 30 g dress sample, amount of about 24 g of aluminum alloy has been recovered. The remaining oxides contains aluminum oxide, silicon oxide, magnesium oxide and iron oxide. From the aluminum oxide dissolved in the melt, metallic aluminum is formed by electrolysis in a subsequent stage.
  • 石川 達雄, 上田 幹人
    表面技術 = The Journal of the Surface Finishing Society of Japan 49 4 347 - 351 一般社団法人 表面技術協会 1998年04月01日 [査読無し][通常論文]
  • 上田 幹人, 近田 昭一, 佐々木 健, 石川 達雄
    電気化学および工業物理化学 : denki kagaku 66 2 164 - 170 電気化学会 1998年02月05日 [査読無し][通常論文]
  • M Ueda, S Konda, T Sasaki, T Ishikawa
    DENKI KAGAKU 66 2 164 - 170 1998年02月 [査読有り][通常論文]
     
    Anodic dissolution behavior of several aluminum alloys containing Fe(1 similar to 3 mass%), Si(0.2 similar to 3 mass%) and Mg (0.3 mass%) was investigated in molten salts predominantly composed of chloride, which were developed for electrorefining of aluminum from aluminum scraps in a three-layer cell. During 12 hour electrolysis using the aluminum alloys, the aluminum content in the melts, 5 mol% AlF3-NaF-BaCl2-NaCl, was kept constant and the overvoltage of both anodic and cathodic reactions was negligibly small. It suggested that the melts were applicable to the system for Al electrorefining. The analysis of the melts and the deposited Al every three hours showed that Fe content in the deposited Al was less than 0.01 mass% and that of Mg was negligibly small, and the contents of Si became about one thirtieth of the starting anode alloys. The Fe content up to 3 mass% in anode alloys brought about no significant problems.
  • 近田 昭一, 佐々木 健, 上田 幹人, 石川 達雄
    電気化学および工業物理化学 : denki kagaku 66 1 80 - 85 電気化学会 1998年01月05日 [査読無し][通常論文]
  • 近田 昭一, 佐々木 健, 上田 幹人, 石川 達雄
    電気化学および工業物理化学 : denki kagaku 66 1 74 - 79 電気化学会 1998年01月05日 [査読無し][通常論文]
  • M Ueda, T Sasaki, S Konda, T Ishikawa
    PROCEEDINGS OF THE ELEVENTH INTERNATIONAL SYMPOSIUM ON MOLTEN SALTS XI 98 11 363 - 369 1998年 [査読有り][通常論文]
     
    To investigate the applicability of a vertically stacked bipolar electrode cell to electrorefining of Al from scrap Al, the cell composed of three units was made with anode 61%Al - 37.3%Cu alloy containing 1%Fe and 0.7% Mn (mass) in melt and electrolysis was carried out for six hours at 750 degrees C. As the electricity of 90 Ahr, which corresponded to Al deposition of 30.0g per cathode in 100% current efficiency, was applied, the total mass of electrodeposited Al was 87.5g. The amounts of Mn, Cu and Fe in deposited Al were under 0.003, 0.008 and 0.009 %, respectively; the purity of Al exceeded 99.98%. The concentration of Al components in the 3rd unit containing a terminal anode increased compared with the initial concentration, and that in the Ist unit containing a terminal cathode decreased. It was interpreted that the reaction current through bipolar electrodes became small due to bypass current, and the bipolar electrodes worked almost ideally. The vertically stacked bipolar electrode cell is, therefore, useful for electrorefining of Al from scrap Al, if same counterpane to dissolve the ununiformity of the concentration in the cell is laid down.
  • S Konda, T Sasaki, M Ueda, T Ishikawa
    DENKI KAGAKU 66 1 74 - 79 1998年01月 [査読有り][通常論文]
     
    In order to develop an energy saving process for electrowinning of liquid aluminum from chloride melts, a design principle for a bipolar electrode cell was developed and the design parameters suitable for its operation were determined on the basis of experiments in 25 mol %MgCl2-75mol%NaCl melts containing several mol% AlCl3 at 750 degrees C.
  • S Konda, T Sasaki, M Ueda, T Ishikawa
    DENKI KAGAKU 66 1 80 - 85 1998年01月 [査読有り][通常論文]
     
    The decomposition voltage of aluminum chloride and the electrical conductivity were determined as a function of concentration of aluminum chloride in 25 mol%MgCl2-NaCl melts in order to estimate the characteristics of a bipolar electrode cell. The relations between voltage and applied current were calculated from an equivalent circuit of the bipolar electrode cell of which components were determined by using these properties of the melts and the parameters of the cell design. The calculated relations were in fair agreement with the experimental results. This suggests that the procedure mentioned above makes it possible for us to estimate the characteristics of the cell and select the suitable electrolysis conditions without the operation of the cell.
  • 上田 幹人, 近田 昭一, 佐々木 健, 石川 達雄
    電気化学および工業物理化学 : denki kagaku 64 9 978 - 983 電気化学会 1996年09月05日 [査読無し][通常論文]
  • M Ueda, S Konda, T Sasaki, T Ishikawa
    DENKI KAGAKU 64 9 978 - 983 1996年09月 [査読有り][通常論文]
     
    Electrical conductivity of chloride melts containing fluorides expected to be useful as an Al electrorefining bath was measured by changing distances between a graphite cathode and an aluminum-copper alloy anode. The melts were prepared by adding prescribed amounts of a 40 mol%5 AlF3-NaF double salt to 40 similar to 60 mol% BaCl3-NaCl solvent melts and investigated in the concentration range of AlF3 from 5 to 15 mol%. Electrical conductivities of the melts were determined to be in the region of 2.0 to 2.8 S . cm(-1) at 750 similar to 850 degrees C and the activation energies varied from 1.9 to 2.8 kJ . mol(-1). The electrical conductivity increased with an increase of AlF3 concentration in 50 and 60 mol% BaCl2-NaCl solvent melts, but it decreased in the 40 mol% BaCl2-NaCl solvent melt. The increases in conductivity were due to increase in the mole fraction of Na components in the melts by the addition of 40 mol% AlF3-NaF double salts. The cause for the decrease was also discussed in terms of the increase in complex anions derived from AlF3.
  • 上田 幹人, 近田 昭一, 佐々木 健, 石川 達雄
    電気化学および工業物理化学 : denki kagaku 63 7 664 - 668 電気化学会 1995年07月05日 [査読無し][通常論文]

書籍

  • 電気化学便覧
    上田幹人 (担当:分担執筆範囲:溶融塩・イオン液体、工業電解)
    丸善出版 2012年12月
  • リサイクル・廃棄物辞典
    上田幹人 (担当:分担執筆範囲:近未来の技術と可能性)
    産業調査会 2012年03月
  • イオン液体II
    上田幹人 (担当:分担執筆範囲:イオン液体の定義)
    シーエムシー出版 2006年03月

その他活動・業績

受賞

  • 2020年01月 電気化学会溶融塩委員会 溶融塩賞
     溶融塩・イオン液体を用いた金属電気化学 
    受賞者: 上田幹人
  • 2003年04月 電気化学会 進歩賞(佐野賞)
     
    受賞者: 上田幹人

教育活動情報

主要な担当授業

  • 環境材料学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 環境劣化,腐食,防食,局部電池モデル,不働態皮膜,電気化学、資源リサイクル
  • 環境材料学特論
    開講年度 : 2021年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 環境劣化,腐食,防食,局部電池モデル,不働態皮膜,電気化学、資源リサイクル
  • 材料デザイン工学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 金属材料、電子、原子、結晶構造、機能性、構造材、表面、反応プロセス
  • 材料工学概論
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 金属材料、電子、原子、結晶構造、機能性、構造材、表面、反応プロセス
  • 材料熱力学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 活量、化学ポテンシャル、溶液、電気化学,
  • 環境と人間
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : マテリアル製造、製造プロセス、省エネルギー、地球環境、持続的発展
  • 材料工学演習Ⅰ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 化学ポテンシャル、活量、化学平衡、X線結晶解析、X線回折、結晶構造、ミラー指数、逆格子   
  • マテリアルプロセス工学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 材料熱力学、高温反応プロセス、非鉄金属の製造、座標系、反応操作、分離操作、分子運動論と真空科学技術
  • 材料工学演習Ⅲ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 二元系・三元系平衡状態図、自由エネルギー・組成図、材料熱力学、混合と相平衡、気体の関与する状態図、真空技術、活量、座標系、反応操作、分離操作、精錬反応

大学運営

その他

  • 2011年11月 - 2011年11月  北海道大学説明会(名古屋、大阪にて開催) 工学部担当
  • 2011年07月 - 2011年07月  北見工業大学 非常勤講師
  • 2010年11月 - 2010年11月  北海道大学説明会 (東京にて開催) 工学部担当
  • 2009年11月 - 2009年11月  北海道大学説明会(東京にて開催) 工学部担当
  • 2009年09月 - 2009年09月  北海道大学工学部 工学セミナー(釧路にて開催) 講師
  • 2009年08月 - 2009年08月  北海道大学セミナー(函館にて開催) 工学部の講師
  • 2008年08月 - 2008年08月  北海道大学工学部 工学セミナー(函館にて開催) 講師
  • 2007年 - 2007年  北海道大学工学部北工会 文化部長


Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.