Researcher Profile and Settings

Affiliation

• Faculty of Engineering　Materials Science and Engineering　Ecological Materials

Job Title

• Professor

Degree

• Ph. D.（Hokkaido University）

URL

https://www.eng.hokudai.ac.jp/labo/eco1/

J-Global ID

• 200901064126758886

Research Interests

• Superhydrophilicity and superhydrophobicity   Surface science   Electrochemistry   Corrosion   Porous alumina   Anodizing   

Research Areas

• Nanotechnology/Materials / Composite materials and interfaces
• Nanotechnology/Materials / Material fabrication and microstructure control

Educational Organization

•  Bachelor's degree program　School of Engineering
•  Master's degree program　Graduate School of Engineering
•  Doctoral (PhD) degree program　Graduate School of Engineering

Academic & Professional Experience

• 2023/11 - Today Faculty of Engineering, Hokkaido University Professor
• 2010/05 - 2023/10 Faculty of Engineering, Hokkaido University
• 2007/04 - 2010/04 Graduate School of Engineering, Hokkaido University
• 2004/01 - 2007/03 Graduate School of Engineering, Hokkaido University
• 2003/04 - 2003/12 株式会社フルヤ金属 研究員
• 2000/04 - 2003/03 日本学術振興会 特別研究員（DC1）

Education

• 2000/04 - 2003/03  Hokkaido University  Graduate School of Engineering  Division of Molecular Chemistry
• 1998/04 - 2000/03  Hokkaido University  Graduate School of Engineering  Division of Molecular Chemistry
• 1995/04 - 1998/03  Hokkaido University  School of Engineering
• 1990/04 - 1995/03  国立函館工業高等専門学校

Association Memberships

• American Association for the Advancement of Science   The Electrochemical Society   International Society of Electrochemistry   軽金属学会   表面技術協会ARS（金属のアノード酸化皮膜の機能化部会）   日本金属学会   電気化学会   表面技術協会   

Research Activities

Published Papers

• 高規則ナノディンプル構造に基づくアルミニウム表面の虹色発色

  菊地竜也, 岩井愛

  塗装工学 58 263 - 269 2023 [Not refereed][Invited]
  
• A Novel Polishing Process for Ultra-Smooth Aluminum Surfaces via Anodizing in Sodium Metaborate

  Mana Iwai, Tatsuya Kikuchi

  Journal of The Electrochemical Society 170 073506  2023 [Refereed][Not invited]
  
• Electrochemical Separation of Porous Anodic Aluminum Oxide with Thick Barrier Layers

  Tatsuya Kikuchi, Kazuya Miyamoto, Mana Iwai

  Journal of The Electrochemical Society 170 073504  2023 [Refereed][Not invited]
  
• アルマイトの安全な超高速電解剥離法

  菊地竜也, 宮本和哉, 岩井愛

  アルトピア 53 (4) 14 - 21 2023 [Not refereed][Invited]
  
• Chemical stability of porous anodic aluminum oxide in both acidic and alkaline solutions

  Mana Iwai, Tatsuya Kikuchi

  Thin Solid Films 771 139784 - 139784 0040-6090 2023 [Refereed][Not invited]
  
• Nanomorphological changes of anodic aluminum oxide fabricated by anodizing in various phosphate solutions over a wide pH range

  Ayasa Terashima, Mana Iwai, Tatsuya Kikuchi

  Applied Surface Science 605 154687  0169-4332 2022 [Refereed][Not invited]
   

  High-purity aluminum plates were anodized in phosphoric acid and six phosphate solutions over a wide pH range from acidic to alkaline. The current density corresponding to the growth rate of the anodic oxide was minimum when anodizing in near-neutral solutions and increased when the pH value increased or decreased. A typical porous anodic aluminum oxide (PAAO) film consisting of an outer porous layer and inner hemispherical barrier layer, which is based on the Keller-Hunter-Robinson (KHR) model, was formed in acidic solutions. At the pH values closer to the neutral region, a uniform barrier oxide film or a PAAO film with a narrow porous layer was produced owing to the low solubility of aluminum oxide. On the other hand, two types of characteristic PAAO films were formed during anodizing in alkaline phosphate solutions: one was a PAAO film consisting of an outer porous layer with feathered pore walls and inner hemispherical barrier layer, and the second was a PAAO film consisting of an outer porous layer with elongated pores and inner flat barrier layer. We showed that novel PAAO films, which are not based on the KHR model, can be prepared by anodizing aluminum in various alkaline phosphate solutions.
• Rapid electrochemical separation of anodic porous alumina films from aluminum surfaces using a highly safe sodium chloride–ethylene glycol solution

  Kazuya Miyamoto, Mana Iwai, Tatsuya Kikuchi

  Electrochimica Acta 427 140865  2022 [Refereed][Not invited]
  
• Slippery and Sticky Superoleophobicities on Hierarchical Aluminum Surfaces Fabricated by Electrochemical Etching and Anodizing Methods

  Tatsuya Kikuchi, Junnosuke Yasuda, Mana Iwai

  Journal of The Electrochemical Society 169 (5) 053509  0013-4651 2022 [Refereed][Not invited]
   

  Slippery and sticky superoleophobic aluminum surfaces were fabricated by electrochemical etching and anodizing methods. Collective structures of sub-micrometer-scale cubic-shaped aluminum were formed by electrochemical etching of high-purity aluminum in HCl. The etched specimens were then anodized in H4P2O7 to form anodic alumina nanofibers (AANFs) on the cubic aluminum surface, resulting in a hierarchical aluminum-alumina structure. As the water/oil-repellent self-assembled monolayers were formed on their surfaces, the superoleophobicity of dodecane was more than 150 degrees in the advancing contact angle exhibited on the anodizing surfaces. Conversely, the receding contact angle changed drastically with anodizing time because of the different nanomorphology of AANFs; short anodizing caused slippery superoleophobicity with high contact angle values, whereas long anodizing resulted in sticky superoleophobicity with 0 degrees. We demonstrated the slipping behavior of dodecane droplets on superoleophobic aluminum surfaces with completely opposite sliding properties. The corrosion resistant property of the superoleophobic aluminum surface was also investigated by the measurements of potentiodynamic curve in a 3.5 wt% sodium chloride solution.
• 陽極酸化によるアルミニウムの表面処理

  菊地竜也, 岩井愛

  色材協会誌 95 85 - 91 2022 [Refereed][Invited]
  
• Formation of Bright White Plasma Electrolytic Oxidation Films with a Uniform Maze-Like Structure by Anodizing Aluminum in Ammonium Tetraborate Solutions

  Tatsuya Kikuchi, Miu Sato, Mana Iwai, Daiki Nakajima, Junji Nunomura, Yoshiyuki Oya, Shungo Natsui

  Journal of The Electrochemical Society 169 (4) 043505 - 043505 0013-4651 2022 [Refereed][Not invited]
   

  Bright white plasma electrolytic oxidation (PEO) films with uniform maze-like structures were obtained by anodizing Al in an ammonium tetraborate solution. High-purity Al plates were galvanostatically anodized in 0.3–2.4 M ammonium tetraborate solutions at 303–343 K and 10–100 Am⁻². A PEO film consisting of an outer porous layer consisting of amorphous alumina and crystalline alumina with α-and γ-phases and an inner amorphous barrier alumina layer was obtained on the Al surface. An extremely uneven PEO film with various pore sizes and many cracks was formed in a 0.3 M ammonium tetraborate solution, whereas a relatively uniform porous PEO film with similar pore sizes was obtained in 0.9–2.4 M solutions. This difference in the PEO film morphology was due to the plasma generation behavior while anodizing. The lightness of the PEO film increased with increasing anodizing time and PEO film thickness; thus, a bright white PEO film measuring 87.5 in lightness (L*) was formed on the Al surface. The water wettability of the PEO film exhibited weak hydrophilicity. Moreover, a superhydrophobic PEO film with a contact angle of 154° was easily fabricated by self-assembled monolayer modification. Similar bright white PEO coatings were successfully fabricated on various industrial alloys.
• Droplet behavior analysis on inclined, highly sticky, or slippery superhydrophobic nanostructured surfaces by observation and SPH simulation

  Shungo Natsui, Kazui Tonya, Daiki Nakajima, Tatsuya Kikuchi, Hiroshi Nogami

  Chemical Engineering Science 248 117214 - 117214 0009-2509 2022 [Refereed][Not invited]
  
• Quantification of the Impact of Residual H2O on Cathodic Behavior in Molten CaCl2 Electrolysis

  Shungo Natsui, Ryota Shibuya, Ryosuke O. Suzuki, Tatsuya Kikuchi, Akihisa Ito, Takahiro Sato, Rei Yamamoto, Hiroshi Nogami

  Journal of Sustainable Metallurgy 8 532 - 540 2022 [Refereed]
  
• Recent Studies on Titanium Refining: 2017-2020

  Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi

  Materials Transactions 62 905 - 913 2021 [Refereed][Invited]
  
• Fabrication of Porous Alumina by Anodizing Aluminum and Its Applications

  Tatsuya Kikuchi, Mana Iwai

  Denki Kagaku 89 327 - 333 2021 [Not refereed][Invited]
  
• Fabrication of unique porous alumina films with extremely high porosity and an ultra-flat barrier layer by anodizing aluminum in sodium metaborate

  Mana Iwai, Tatsuya Kikuchi

  Electrochimica Acta 399 139440  0013-4686 2021 [Refereed][Not invited]
   

  Unique porous anodic aluminum oxide (PAAO) films with a completely flat barrier layer and an extremely porous loofah-like structure were fabricated by anodizing aluminum in an alkaline sodium metaborate solution. High-purity aluminum plates were anodized in a 0.3 M sodium metaborate solution at various applied voltages in the range of 0.1-200 V. A typical PAAO film with a spherical cap barrier layer was formed at voltages lower than 50 V, whereas a PAAO film with a flat barrier layer was formed at voltages higher than 100 V; this film formation was not based on the Keller-Hunter-Robinson model with the spherical barrier layer. The growth interface of the flat barrier layer exhibited an ultra-flat morphology with a minimum roughness value of 0.4 nm, which is much smaller than that of an electropolished aluminum surface. Such barrier layer morphology is expected to be formed by field-assisted dissolution without oxide flow. Although the current density slightly decreased with the applied voltage, a relatively higher current density of 6.8 Am-2 was still measured at the lowest voltage of 0.1 V. The alumina walls and the bottom barrier layer gradually thinned as the applied voltage decreased, and a loofah-like PAAO film with an ultra-high porosity of 0.93 was successfully fabricated at 0.1 V. The anodic oxide consisted of amorphous, anion-free aluminum oxide. (C) 2021 The Authors. Published by Elsevier Ltd.
• Self-Ordering of Porous Anodic Alumina Fabricated by Anodizing in Chromic Acid at High Temperature

  Tatsuya Kikuchi, Motoki Yamashita, Mana Iwai, Ryosuke O. Suzuki

  Journal of The Electrochemical Society 168 (9) 093501  0013-4651 2021 [Refereed][Not invited]
   

  Anodizing Al in chromic acid is a very useful surface finishing process for corrosion protection and nanoscale porous structure fabrication, whereas the self-ordering of porous anodic alumina (PAA) in chromic acid has never been found to date. Herein, we provide a self-ordered PAA film possessing numerous sub100-nm-scale characteristic bumps through anodizing in chromic acid at high temperature. Anodizing of high purity Al plates in a 0.3 M chromic acid solution at conventional low temperatures, such as 293 K, leads to the formation of a disordered PAA film, whereas anodizing at a high temperature of 348 K causes the self-ordering behavior of the pore structure. The PAA film grown in the initial stage possessed the highest regularity, and it decreased with anodizing time due to pore branching during anodizing. A highly ordered PAA film measuring approximately 340 nm in interpore distance can be fabricated by short-term, two-step anodizing in chromic acid at 348 K and 120 V. The ordered PAA film possesses a characteristic nanostructure consisting of hexagonally arranged 100-nm-scale pores and sub100-nm-scale disordered bumps on their pore walls without any electrolyte chromate anion.
• Synthesis of Silicon Sulfide by Using CS2 Gas

  Ryosuke O. Suzuki, Yuta Yashima, Takumi Kaneko, Eltefat Ahmadi, Tatsuya Kikuchi, Takafumi Watanabe, Genki Nogami

  Metallurgical and Materials Transactions B 52 1379 - 1391 2021 [Refereed][Not invited]
  
• Self-ordered nanospike porous alumina fabricated under a new regime by an anodizing process in alkaline media

  Mana Iwai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Scientific Reports 11 (1) 7240  2045-2322 2021 [Refereed]
   

  High-aspect ratio ordered nanomaterial arrays exhibit several unique physicochemical and optical properties. Porous anodic aluminum oxide (AAO) is one of the most typical ordered porous structures and can be easily fabricated by applying an electrochemical anodizing process to Al. However, the dimensional and structural controllability of conventional porous AAOs is limited to a narrow range because there are only a few electrolytes that work in this process. Here, we provide a novel anodizing method using an alkaline electrolyte, sodium tetraborate (Na2B4O7), for the fabrication of a high-aspect ratio, self-ordered nanospike porous AAO structure. This self-ordered porous AAO structure possesses a wide range of the interpore distance under a new anodizing regime, and highly ordered porous AAO structures can be fabricated using pre-nanotexturing of Al. The vertical pore walls of porous AAOs have unique nanospikes measuring several tens of nanometers in periodicity, and we demonstrate that AAO can be used as a template for the fabrication of nanomaterials with a large surface area. We also reveal that stable anodizing without the occurrence of oxide burning and the subsequent formation of uniform self-ordered AAO structures can be achieved on complicated three-dimensional substrates.
• A Sustainable Approach for Producing Ti and TiS2 from TiC

  Eltefat Ahmadi, Ryosuke O Suzuki, Takumi Kaneko, Tatsuya Kikuchi

  Metallurgical and Materials Transactions B 52 77 - 87 2021 [Refereed][Not invited]
  
• Influence of sub-10 nm anodic alumina nanowire morphology formed by two-step anodizing aluminum on water wettability and slipping behavior

  Tatsuya Kikuchi, Fumiya Onoda, Mana Iwai, Ryosuke O. Suzuki

  Applied Surface Science 546 149090  0169-4332 2021 [Refereed][Not invited]
   

  The influence of the nanomorphology of alumina nanowires (ANWs) fabricated by a two-step anodizing process on the superhydrophobicity was investigated through advancing contact angle (ACA) and receding contact angle (RCA) measurements. Aluminum nanobowl specimens were anodized in pyrophosphoric acid to fabricate an ordered ANW structure with an average diameter of 7.1 nm, and the outermost surface of the ANWs was chemically bonded with fluorinated self-assembled monolayers. The growing ANWs bent immediately their own weight, and pyramidal ANW structures were formed as they joined the surrounding nanowires together. The ACA value increased with the number density of pyramidal ANW structures due to the reducing area fraction of ANWs, and an increased superhydrophobicity with a contact angle of approximately 165. was measured on the low-density pyramidal structure with a density of 8.1 x 10(11) m(-2). Additional anodizing led to complete nanowire bending; thus, the advancing contact angle decreased. The pyramidal nanowire structure exhibited a large slipping property with a contact angle hysteresis (CAH) < 10 degrees, whereas the bent nanowire structure exhibited a decreased slipping property with a CAH > 100 degrees. Superhydrophobic surfaces with opposite water slipping properties were demonstrated by a water dropping experiment.
• High-speed galvanostatic anodizing without oxide burning using a nanodimpled aluminum surface for nanoporous alumina fabrication

  Mana Iwai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Applied Surface Science 537 147852  0169-4332 2021 [Refereed][Not invited]
   

  Rapid formation of a porous alumina film without oxide burning was achieved by anodizing in etidronic acid at large current densities using a nanodimpled aluminum surface. After the electropolished aluminum specimens were galvanostatically anodized in a 0.3 M etidronic acid solution at 293 K, a uniform porous alumina film without oxide burning was formed at relatively low current densities of up to 20 Am-2. After the first anodizing process, an array of dimples was fabricated on the aluminum surface by oxide film removal in a chromic acid/phosphoric acid solution. After the nanostructured aluminum specimen was galvanostatically anodized once again under the same conditions, the possible applied current density without burning increased with the size of the nanodimples, and the current density during the high-speed anodizing process of the dimpled aluminum specimen increased by five times. Many pores grew on the whole surface of the aluminum dimples from the initial anodizing stage; then, pores that grew from the bottom of the dimples survived the anodizing process, and a clear porous alumina film was formed as the voltage reached the maximum value.
• SPH Simulations of binary droplet deformation considering the Fowkes theory

  Shungo Natsui, Kazui Tonya, Hiroshi Nogami, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Chemical Engineering Science 229 116035 - 116035 0009-2509 2021 [Refereed][Not invited]
  
• Topological Consideration of 3-D Local Void Structure for Static Holdup Site in Packed Bed

  Shungo Natsui, Akinori Sawada, Hiroshi Nogami, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ISIJ International 60 1453 - 1460 2020 [Refereed][Not invited]
  
• 軽金属学会年間レビュー「腐食・表面処理」

  菊地竜也

  軽金属 70 362 - 364 2020 [Refereed][Invited]
  
• Towards a Sustainable Technology for Production of Extra-Pure Ti Metal: Electrolysis of Sulfurized Ti(C,N) in Molten CaCl2

  Eltefat Ahmadi, Ryosuke O Suzuki, Tatsuya Kikuchi, Takumi Kaneko, Yuta Yashima

  International Journal of Minerals, Metallurgy and Materials 27 1635 - 1643 2020 [Refereed][Not invited]
  
• Anodizing Aluminum and Its Alloys in Etidronic Acid to Enhance Their Corrosion Resistance in a Sodium Chloride Solution

  Tatsuya Kikuchi, Yusuke Suzuki, Mana Iwai, Ryosuke O. Suzuki

  Journal of The Electrochemical Society 167 (12) 121502  0013-4651 2020 [Refereed][Not invited]
   

  The formation behaviors of the anodic oxide film that forms on various commercially available aluminum plates were investigated by galvanostatic anodizing in etidronic acid, and their corrosion resistances were examined in a 3.5 wt% NaCl solution. High-purity aluminum and A1050, A5052, and A7075 aluminum alloys were galvanostatically anodized in an etidronic acid solution. An amorphous porous oxide film formed on the pure aluminum, the A1050 alloy, and the A5052 alloy, whereas a plasma electrolytic oxidation (PEO) film formed on the A7075 alloy. The nanopores formed in the porous oxide film could be sealed with hydroxides by immersion in boiling water. Corrosion-resistant pure aluminum with a measured corrosion current density ofi(corr)= 10(-9)Am(-2)could be formed by anodizing and subsequent pore-sealing. Although the corrosion current increased due to the presence of alloying elements in the matrix, the fabrication of the corrosion-resistant A1050 and A5052 alloys withi(corr)= 10(-6)Am(-2)could also be achieved by anodizing. Alternately, the corrosion resistance of the A7075 alloy covered with the PEO film was measured to bei(corr)= 10(-4)Am(-2), which is not as small as thei(corr)of the A1050 and A5052 alloys due to its open microporous structure.
• 陽極酸化によるアルミニウム表面のナノ構造制御と超親水性・超撥水性の発現

  菊地竜也, 中島大希, 近藤龍之介, 鈴木亮輔, 夏井俊悟

  機能材料 40 (6) 24 - 30 2020 [Not refereed][Invited]
  
• Characterization of the Cathodic Thermal Behavior of Molten CaCl2 and Its Hygroscopic Chloride Mixture During Electrolysis

  Ryota Shibuya, Shungo Natsui, Hiroshi Nogami, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Journal of The Electrochemical Society 167 (10) 102507  2020 [Refereed][Not invited]
  
• Photoluminescence from Anodic Aluminum Oxide via Etidronic Acid Anodizing and Enhancing the Intensity

  Tatsuya Kikuchi, Shunta Akiya, Kaito Kunimoto, Shungo Natsui, Ryosuke O. Suzuki

  Materials Transactions 61 1130 - 1137 2020 [Refereed][Not invited]
  
• Initial Structural Changes of Porous Alumina Film via High-Resolution Microscopy Observations

  Mana Iwai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ECS Journal of Solid State Science and Technology 9 (4) 044004  2020 [Refereed][Not invited]
  
• Numerical Study of Binary Trickle Flow of Liquid Iron and Molten Slag in Coke Bed by Smoothed Particle Hydrodynamics

  Shungo Natsui, Kazui Tonya, Hiroshi Nogami, Tatsuya Kikuchi, Ryosuke O. Suzuki, Ko-ichiro Ohno, Sohei Sukenaga, Tatsuya Kon, Shingo Ishihara, Shigeru Ueda

  Processes 8 (2) 221  2020 [Refereed][Not invited]
   

  In the bottom region of blast furnaces during the ironmaking process, the liquid iron and molten slag drip into the coke bed by the action of gravity. In this study, a practical multi-interfacial smoothed particle hydrodynamics (SPH) simulation is carried out to track the complex liquid transient dripping behavior involving two immiscible phases in the coke bed. Numerical simulations were performed for different conditions corresponding to different values of wettability force between molten slag and cokes. The predicted dripping velocity changes and interfacial shape were investigated. The relaxation of the surface force of liquid iron plays a significant role in the dripping rate; i.e., the molten slag on the cokes acts as a lubricant against liquid iron flow. If the attractive force between the coke and slag is smaller than the gravitational force, the slag then drops together with the liquid iron. When the attractive force between the coke and slag becomes dominant, the iron-slag interface will be preferentially detached. These results indicate that transient interface morphology is formed by the balance between the momentum of the melt and the force acting on each interface.
• Fabrication of a PEO/AAO Double-layer Anodic Oxide Film via One-Step Anodizing Aluminum in Ammonium Carbonate

  Tatsuya Kikuchi, Taiki Taniguchi, Ryosuke O. Suzuki, Shungo Natsui

  Thin Solid Films 697 137799  2020 [Refereed][Not invited]
  
• Visualization of TiO2 reduction behavior in molten salt electrolysis

  Shungo Natsui, Takuya Sudo, Ryota Shibuya, Hiroshi Nogami, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Metallurgical Materials Transactions B 51 11 - 15 2020 [Refereed][Not invited]
  
• Nanostructural characterization of ordered gold particle arrays fabricated via aluminum anodizing, sputter coating, and dewetting

  Hiroki Ikeda, Mana Iwai, Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Norihito Sakaguchi, Ryosuke O. Suzuki

  Applied Surface Science 465 747 - 753 0169-4332 2019 [Refereed][Not invited]
   

  Gold nanoparticles were fabricated on an ordered aluminum dimple array via aluminum anodizing, sputter coating, and thermal treatment, and the transformation behavior and nanostructural characterization were investigated in detail. Electropolished aluminum specimens were anodized in an oxalic acid solution under self-ordering conditions at 40 V, and then the porous alumina was selectively dissolved to expose an ordered aluminum dimple array with each dimple measuring 100 nm. A thin layer of gold was coated onto the dimple array, and a thermal treatment was subsequently performed. The gold layer was transformed into numerous particles by the thermal treatment due to dewetting. When the values of gold layer thickness, thermal treatment temperature, and thermal treatment duration were optimized, the gold particles were located at the bottom of each aluminum dimple. Consequently, multiply-twinned particles with polygonal and elliptical shapes were regularly distributed on the aluminum dimple array treated at 473 K. Although the rate of the transformation induced by dewetting increased with the temperature of the thermal treatment, non-uniform gold nanostructures were formed by extended thermal treatment at 873 K. The gold particles formed on the aluminum surface exhibited excellent adhesion upon ultrasonication.
• 高温融体界面と分散層挙動の数値解析 －Smoothed Particle Hydrodynamics法の製錬プロセス解析への応用－

  夏井俊悟, 梨元涼太, 問谷一偉, 澤田旺成, 菊地竜也, 鈴木亮輔

  Journal of MMIJ 135 71 - 82 2019 [Not refereed][Invited]
  
• A superhydrophilic Aluminum Surface with Fast Water Evaporation Based on Anodic Alumina Bundle Structures via Anodizing in Pyrophosphoric Acid

  Daiki Nakajima, Tatsuya Kikuchi, Taiki Yoshioka, Hisayoshi Matsushima, Mikito Ueda, Ryosuke O. Suzuki, Shungo Natsui

  Materials 12 3497  2019 [Refereed][Not invited]
  
• TiO2溶融塩電解還元時のガス発生反応

  原口靖史, 澁谷凌太, 夏井俊悟, 菊地竜也, 鈴木亮輔

  日本金属学会誌 83 441 - 448 2019 [Refereed][Invited]
  
• Electrochemical and Morphological Characterization of Porous Alumina Formed by Galvanostatic Anodizing in Etidronic Acid

  Mana Iwai, Tatsuya Kikuchi, Ryosuke O. Suzuki, Shungo Natsui

  Electrochimica Acta 320 134606  0013-4686 2019 [Refereed][Not invited]
   

  Electrochemical and morphological characterization of the porous alumina formed by galvanostatic anodizing in etidronic acid under various operating conditions was performed. High-purity aluminum plates were anodized in 0.03-3 M etidronic acid solutions at 273-333 K and 0.25-500 Am-2 for up to 24 h. Galvanostatic anodizing in etidronic acid operated over a wide range voltage measuring from a few V to 246 V. The time required for the steady growth of porous alumina not only depends on the current density but also the temperature and the concentration of the electrolyte solution during galvanostatic anodizing. The average, maximum, and minimum cell sizes of the porous alumina were directly proportional to the anodizing voltage with a proportionality constant of 2.5, 3.5 and 0.7, respectively, and were independent of other parameters. The number density of the cell was also a function of the anodizing voltage and agreed with the theoretical value obtained for ordered porous alumina with an ideal honeycomb distribution. The maximum voltage measured during galvanostatic anodizing was linearly proportional to the plateau voltage with a proportionality constant of 1.4. (C) 2019 Elsevier Ltd. All rights reserved.
• Corrosion-Resistant Porous Alumina Formed via Anodizing Aluminum in Etidronic Acid and its Pore-Sealing Behavior in Boiling Water

  Yusuke Suzuki, Kai Kawahara, Tatsuya Kikuchi, Ryosuke O. Suzuki, Shungo Natsui

  Journal of The Electrochemical Society 166 C261 - C269 2019 [Refereed][Not invited]
  
• Fabrication of Anodic Porous Alumina via Galvanostatic Anodizing in Alkaline Sodium Tetraborate Solution and Their Morphology

  Tatsuya Kikuchi, Kaito Kunimoto, Hiroki Ikeda, Daiki Nakajima, Ryosuke O. Suzuki, Shungo Natsui

  Journal of Electroanalytical Chemistry 846 113152  2019 [Refereed][Not invited]
  
• Solubility of CaS in CaCl2-LiCl Eutectic Melt

  Takahiro Matsuzaki, Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi, Mikito Ueda

  Materials Transactions 60 411 - 415 2019 [Refereed][Not invited]
  
• Solubility of CaS in Molten CaCl2

  Takahiro Matsuzaki, Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi, Mikito Ueda

  Materials Transactions 60 386 - 390 2019 [Refereed][Not invited]
  
• Calciothermic Reduction and Electrolysis of Sulfides in CaCl2 Melt

  Ryosuke O. Suzuki, Nobuyoshi Suzuki, Yuta Yashima, Shungo Natsui, Tatsuya Kikuchi

  Proceedings of the First Global Conference on Extractive Metallurgy (Extraction2018), ed. by B.R.Davis, M.S.Moats, S.Wang, The Minerals, Metals & Materials Society 2018, Springer, Cham, Switzerland 763 - 771 2018/09 [Refereed][Not invited]
   

  A new metallurgical process via sulfide is proposed: a sulfide is produced at a high temperature from its metallic oxide using gaseous CS2, and this sulfide is electrochemically reduced to its metallic state using molten salt. This combined process via sulfide is effective to obtain high purity of metallic powder, even if the metal in its oxide is strongly combined with oxygen. For example, it is not easy to reduce stable oxide TiO2, and only Ca can remove oxygen to form α-Ti. However, a fairly large amount of oxygen remains as Ti–O solid solution. Because the solubility of S in Ti is very small, this proposal was examined experimentally both on the conversion of TiO2 to TiS2 and on the successive reduction of TiS2 to Ti. TiO2 powder was exposed to CS2 gas flow at 1073 K, and the conversion to TiS2 was confirmed. TiS2 could be reduced to Ti powder either by calciothermic reduction or electrolysis in a CaCl2 melt. By Ca reduction at 1133 K in CaCl2 melt, sulfur concentration decreased to 0.03 mass%S when the amount greater than twice the stoichiometric calcium amount is added. By electrochemical reduction at 1173 K in CaCl2–CaS melt, S concentration significantly decreased to 0.01 mass%S when four times larger amount of electric charge was supplied.
• (Invited) Metal Production in CaCl2-Based Melts

  Ryosuke O. Suzuki, Hiromi Noguchi, Yasushi Haraguchi, Shungo Natsui, Tatsuya Kikuchi

  ECS Meeting Abstracts 86 (14) 45 - 53 2018/07/23 [Refereed][Invited]
   

  In order to produce metals directly from the oxides, molten CaO-CaCl2 mixture offers a strong reducing environment. CaO in CaCl2 melt electrochemically decomposes into metallic Ca and O2- by applying a certain voltage larger than the theoretical decomposition voltage of CaO. Ca, deposited on cathode and dissolved in the melt, can work as strong reductant. Various metals such as Ti can be produced directly from their stable oxides. Although this calciothermic reduction forms CaO as by-product close to the cathode, CaO dissolves in CaCl2 melt and decomposes again by electrolysis. This OS process could be applied to solid, liquid and gaseous oxides. By applying the sulfides, good quality of metal is realized because they do not form solid solution of sulfur.
• Mirror-finished superhydrophobic aluminum surfaces modified by anodic alumina nanofibers and self-assembled monolayers

  Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  Applied Surface Science 440 506 - 513 0169-4332 2018/05/15 [Refereed][Not invited]
   

  We demonstrate mirror-finished superhydrophobic aluminum surfaces fabricated via the formation of anodic alumina nanofibers and subsequent modification with self-assembled monolayers (SAMs). High-density anodic alumina nanofibers were formed on the aluminum surface via anodizing in a pyrophosphoric acid solution. The alumina nanofibers became tangled and bundled by further anodizing at low temperature because of their own weight, and the aluminum surface was completely covered by the long falling nanofibers. The nanofiber-covered aluminum surface exhibited superhydrophilic behavior, with a contact angle measuring less than 10°. As the nanofiber-covered aluminum surface was modified with n-alkylphosphonic acid SAMs, the water contact angle drastically shifted to superhydrophobicity, measuring more than 150°. The contact angle increased with the applied voltage during pyrophosphoric acid anodizing, the anodizing time, and the number of carbon atoms contained in the SAM molecules modified on the alumina nanofibers. By optimizing the anodizing and SAM-modification conditions, superhydrophobic behavior could be achieved with only a brief pyrophosphoric acid anodizing period of 3 min and subsequent simple immersion in SAM solutions. The superhydrophobic aluminum surface exhibited a high reflectance, measuring approximately 99% across most of the visible spectrum, similar to that of an electropolished aluminum surface. Therefore, our mirror-finished superhydrophobic aluminum surface based on anodic alumina nanofibers and SAMs can be used as a reflective mirror in various optical applications such as concentrated solar power systems.
• Fabrication of ordered submicrometer-scale convex lens array via nanoimprint lithography using an anodized aluminum mold

  Kai Kawahara, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  Microelectronic Engineering 185-186 61 - 68 0167-9317 2018/01/05 [Refereed][Not invited]
   

  The fabrication of submicrometer-scale ordered convex lens array was demonstrated through nanoimprint lithography using an aluminum dimple array mold fabricated by etidronic acid anodizing and selective oxide dissolution. Highly-pure aluminum plates were anodized in a 0.2 M etidronic acid solution at 260 V for the formation of ordered porous alumina. The anodized specimens were immersed in a 0.2 M CrO3/0.51 M H3PO4 solution to dissolve the porous alumina, and an ordered dimple array measuring approximately 670 nm in dimple diameter was obtained on the aluminum surface. Phosphonic acid-based self-assembled monolayers (SAMs) were coated on the aluminum dimple array as a release agent for nanoimprint lithography. The shape of the aluminum dimple array mold was transferred to a UV curable photopolymer by nanoimprint lithography. An ordered convex lens array, which corresponded to the negative shape of the dimple array, was successfully obtained by the removal of curable polymer. However, the polymer surface was contaminated with phosphonate molecules due to the multilayered phosphonate films being formed on the aluminum mold. This contamination can be avoided by ultrasonication of the aluminum mold before nanoimprint lithography.
• Spontaneous colloidal metal network formation driven by molten salt electrolysis

  Shungo Natsui, Takuya Sudo, Takumi Kaneko, Kazui Tonya, Daiki Nakajima, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Scientific Reports 8 13114  2018 [Refereed][Not invited]
  
• Column and film lifetimes in bubble-induced two-liquid flow

  Shungo Natsui, Ryota Nashimoto, Daiki Nakajima, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Physical Review E 97 062802  2018 [Refereed][Not invited]
  
• Holdup characteristics of melt in coke beds of different shapes

  Shungo Natsui, Akinori Sawada, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ISIJ International 58 1742 - 1744 2018 [Refereed][Not invited]
  
• 回転強度試験における時系列3D scanningと固気液三相の移動解析によるコークス変形が及ぼす充填層内流れ特性評価

  夏井俊悟, 澤田旺成, 照井光輝, 柏原佑介, 菊地竜也, 鈴木亮輔

  鉄と鋼 104 347 - 357 2018 [Refereed][Not invited]
  
• Reduction of CaTiO3 by electrolysis in the molten salt CaCl2-CaO

  Hiromi Noguchi, Shungo Natsui, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Electrochemistry 86 (2) 82 - 87 2186-2451 2018 [Refereed][Not invited]
   

  The reduction of CaTiO3 to generate Ti powder with a low content of oxygen was examined by electrolysis in a CaCl2- CaO melt. Using various sizes of the raw oxide particles, the concentration profile of the residual oxygen in the cathode basket suggests a reduction mechanism involving calcium from the melt. The residual oxygen content was influenced by the dehydration method. Vacuum dehydration above the melting temperature and decomposition of CaCl2 hydrates below 550K were required to eliminate water. Optimization of both water removal and the oxide particle size produced the lowest oxygen content (0.42mass%O) in the powder.
• 表面ナノ構造に基づく新規機能性アルミニウム材料の開発

  菊地竜也, 中島大希, 池田大樹, 近藤竜之介, 河原魁, 國本海斗, 岩井愛, 鈴木雄介, 秋谷俊太, 竹永章正, 西長理, 夏井俊悟, 鈴木亮輔

  軽金属 68 211 - 218 2018 [Refereed][Invited]
  
• Detailed Modeling of Melt Dripping in Coke Bed by DEM - SPH

  Natsui, Shungo, Ohno, Ko-ichiro, Sukenaga, Sahel, Kikuchi, Tatsuya, Suzuki, Ryosuke O.

  ISIJ INTERNATIONAL 58 (2) 282 - 291 0915-1559 2018 [Refereed][Not invited]
   

  A high-resolution numerical model was performed for a detailed understanding of packed-bed structures constructed by actual scale cokes, and the molten slag (SiO2-CaO-Al2O3) trickle flow characteristics in the lower part of an actual blast furnace. Smoothed particle hydrodynamics (SPH) simulations can track the motion of liquids containing dispersed droplets, and the discrete element method (DEM) with a multi sphere approach makes possible to simulate non-spherical solid-particle motion. We carried out high resolution large-scale trickle flow simulations using more than 10 million particles, carried out case studies of statistical processing, and evaluated the effects of physical properties varied by the composition or temperature of slag samples. We clarified that there is a limitation to predict the holdup accurately based on the capillary number, which is a widely used approach. We analyzed the influence of melt viscosity on trickle flow, and clarified that an increase in viscosity increases holdup because limiting the effective flow path and suppressing the dispersion of the droplets promoted the enlargement of each stagnant droplet. This detailed direct dynamic model could explain the mechanism underlying different holdup tendencies in conventional research.
• DEM-SPH study of molten slag trickle flow in coke bed

  Shungo Natsui, Akinori Sawada, Koki Terui, Yusuke Kashihara, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Chemical Engineering Science 175 25 - 39 0009-2509 2018 [Refereed][Not invited]
   

  A fully-Lagrangian numerical model was applied for understanding packed bed structures containing non-spherical solids, such as coke, and the high-temperature melt trickle flow characteristics of such beds. Smoothed-particle hydrodynamics (SPH) simulations can track the motion of liquids without discriminating between continuous and dispersed phases, and the extended discrete element method (DEM) is employed as a highly accurate method for simulation of non-spherical solid-particle motion. Based on this model, we carried out large-scale trickle flow simulations using more than 10 million particles, investigated case studies of statistical processing, and evaluated the effects of packed bed formed from various non-spherical coke samples. We found that the pathway that the passing rivulet takes down depends on the structure of the void and the neck size between two voids. If the connecting neck is larger than the capillary length λ=σ/ρg, the slag will drain. The shape of pathway was related that the solids shape factor which is considered by the projected area in the direction of gravity. Even if cokes with similar size were obtained by sieving, low sphericity cokes block slag flow through channeling voids, i.e., as the projected area of the non-spherical solid shape increased, the liquid hold up showed a tendency to increase.
• アルミニウムのポーラス型アノード酸化皮膜

  菊地竜也, 岩井愛, 中島大希, 夏井俊悟, 鈴木亮輔

  表面技術 69 554 - 561 2018 [Refereed][Invited]
  
• Advancing and Receding Contact Angle Investigations for Highly Sticky and Slippery Aluminum Surfaces Fabricated from Nanostructured Anodic Oxide

  Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  RSC Advances 8 37315 - 37323 2018 [Refereed][Not invited]
  
• Superhydrophilic and superhydrophobic aluminum alloys fabricated via pyrophosphoric acid anodizing and fluorinated SAM modification

  Ryunosuke Kondo, Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  JOURNAL OF ALLOYS AND COMPOUNDS 725 379 - 387 0925-8388 2017/11 [Refereed][Not invited]
   

  The fabrication of superhydrophilic and superhydrophobic aluminum alloys was achieved by pyrophosphoric acid anodizing and SAM (self-assembled monolayer) modification. The anodizing of three kinds of aluminum alloys, including 3004, 1N30, and 8021, in a concentrated pyrophosphoric acid solution resulted in the formation of numerous anodic alumina nanofibers. In addition, insoluble intermetallic compounds contained in the alloy matrix were exposed to the surface with increasing anodizing time, and nanofiber-tangled intermetallic particles also formed on the surface during anodizing. These anodized aluminum alloys exhibited a superhydrophilic behavior measuring less than 4 degrees in the contact angle, and this superhydrophilicity was maintained via the long-term anodizing process. The nanofiber-covered aluminum alloys were immersed in fluorinated phosphonic acid SAM/ethanol solutions, thereby modifying SAMs on the anodic alumina nanofibers. The contact angle of the SAM-modified aluminum alloys increased with the immersion time and temperature of the SAM solution, and the surface was drastically shifted to superhydrophobicity, measuring more than 150 degrees, from superhydrophilicity. However, exceeding 10 min in the anodizing process caused the contact angle to decrease and the gradual disappearance of hydrophobicity due to the formation of many hydrophilic intermetallic particles on the surface. The short-term pyrophosphoric acid anodizing and subsequent SAM modification are useful for the formation of various superhydrophilic and superhydrophobic aluminum alloys. (C) 2017 Elsevier B.V. All rights reserved.
• Fabrication of porous tungsten oxide via anodizing in an ammonium nitrate/ethylene glycol/water mixture for visible light-driven photocatalyst

  Tatsuya Kikuchi, Jun Kawashima, Shungo Natsui, Ryosuke O. Suzuki

  APPLIED SURFACE SCIENCE 422 130 - 137 0169-4332 2017/11 [Refereed][Not invited]
   

  Fabrication of a nanoporous tungsten oxide film via anodizing of tungsten in an ammonium nitrate (NH4NO3)/ethylene glycol (EG)/water (H2O) mixture is reported for use as a visible light-driven photocatalyst. Anodizing of tungsten in a 1.0 M NH4NO3/EG solution containing less than 0.1 vol% H2O resulted in active dissolution of the tungsten substrate. As the H2O concentration increased to more than 25 vol%, a thin barrier oxide film was formed on the tungsten substrate. A thick porous tungsten oxide with numerous nanopores measuring several tens of nanometer in diameter was fabricated via anodizing at a moderate H2O concentration of 1.0 vol%. The porous oxide consisted of a double-layered structure with an outer porous layer and an inner dense layer, and the outer porous layer became thinner as the NH4NO3 concentration decreased. A uniform porous oxide film from the top surface to the bottom interface was fabricated via anodizing at 20 V in a 0.02 M NH4NO3/EG solution containing 1.0 vol% H2O at 313 K. The porous tungsten oxide exhibited visible light-driven photocatalytic activity for the photocatalytic decomposition of methylene blue. (C) 2017 Elsevier B.V. All rights reserved.
• Branched morphology of Nb powder particles fabricated by calciothermic reduction in CaCl2 melt

  Nobuyoshi Suzuki, Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi

  JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS 110 58 - 63 0022-3697 2017/11 [Refereed][Not invited]
   

  A new branched morphology of metallic niobium powder particles was produced by calciothermic reduction of niobium oxides in molten CaCl2. The influence of some reaction parameters on the powder particle morphology was studied, and the formation mechanism was investigated. It was found that the formation of intermediate complex niobium oxides (CaxNb2Oy) was crucial in the formation of niobium powder particles with the branched morphology. Based on this finding, the formation mechanism of the branched morphology in four stages was proposed. These Nb powder particles with microscopic branches can prevent particle sintering during the fabrication process of electric capacitors, allowing the latter to exhibit a higher capacitance.
• Advanced hard anodic alumina coatings via etidronic acid anodizing

  Tatsuya Kikuchi, Akimasa Takenaga, Shungo Natsui, Ryosuke O. Suzuki

  SURFACE & COATINGS TECHNOLOGY 326 72 - 78 0257-8972 2017/10 [Refereed][Not invited]
   

  Advanced hard anodic alumina coatings measuring Hv = 610-769on the Vickers hardness scale were obtained on an aluminum surface via aluminum anodizing using a new electrolyte, etidronic acid. The ordered porous alumina was fabricated by two-step etidronic acid anodizing at 260 V under self-ordering conditions, and pore-widening was carried out to control the porosity of the porous alumina. The Vickers hardness of the ordered porous alumina increased with decreasing diameter of the pores and porosity. Aluminum specimens were also anodized by the constant-current method under various concentrations, temperatures, and current densities. The Vickers hardness increased with decreasing concentration and temperature because chemical dissolution of the anodic oxide during anodizing was suppressed. A hard porous alumina measuring Hv = 610 was obtained by anodizing in a 0.05 M etidronic acid solution at 278 K and 5 Am-2. Subsequent thermal treatment caused the dehydration and corresponding hardening of the porous alumina, and a higher porous alumina hardness of Hv = 769 was successfully achieved by thermal treatment at 873 K for 12 h. (C) 2017 Elsevier B.V. All rights reserved.
• Morphology of lithium droplets electrolytically deposited in LiCl-KCl-Li2O melt

  Shungo Natsui, Takuya Sudo, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ELECTROCHEMISTRY COMMUNICATIONS 81 43 - 47 1388-2481 2017/08 [Refereed][Not invited]
   

  We report the growth of electrochemically deposited liquid lithium droplet in LiCl-KCl-Li2O melt at 673-723 K. To understand the transient behavior of liquid lithium in the electrolyte, the interface between the electro-deposited molten metal phase and the molten salt system was observed in situ using a high-speed digital microscope. We found that the droplets on the electrode are slightly flattened, when the colloidal Li content decreases due to an increasing Li2O content. This mechanism indicates that the heterogeneous distribution of the colloid Li may be due to the local Li solubility in the electrolyte.
• Capturing the non-spherical shape of granular media and its trickle flow characteristics using fully-Lagrangian method

  Natsui, Shungo, Nashimoto, Ryota, Kikuchi, Tatsuya, Suzuki, Ryosuke O., Takai, Hifumi, Ohno, Ko-ichiro, Sukenaga, Sohei

  AICHE JOURNAL 63 (6) 2257 - 2271 0001-1541 2017/06 [Refereed][Not invited]
   

  We performed a numerical analysis for simulating granular media structures containing non-spherical elements and the liquid trickle flow characteristics of such structures. Fully-Lagrangian numerical simulation methods can track all motion information for solid or liquid elements at each point in time. We introduced suitable compressibility to moving particle semi-implicit (MPS) and performed individual packing behavior calculations for non-spherical elements, based on discrete element method (DEM) with expanded functions. Rigid bodies-DEM is a method using a DEM contact force model that is expanded to handle the motion of freely shaped solids. It expresses complex shapes to enable low calculation costs and intuitive mounting. We used the boundary for the granular media configured with non-spherical elements to implement a trickle flow simulation based on weakly compressible-MPS. Even for elements of equal volume, different shapes changed the liquid passage velocity and hold-up amount. The mean downflow velocity of the liquid phase was not always dependent on the void fraction. For the plane of projection, we obtained a good correlation with the mean downflow velocity in each packed structure, and successfully performed arrangements according to the new liquid-passage shape coefficient. (c) 2016 American Institute of Chemical Engineers AIChE J, 63: 2257-2271, 2017
• An SPH Study of Molten Matte-Slag Dispersion

  Shungo Natsui, Ryota Nashimoto, Takehiko Kumagai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE 48 (3) 1792 - 1806 1073-5615 2017/06 [Refereed][Not invited]
   

  The transient behaviors of two immiscible liquids, namely, molten matte and molten slag, with a high interfacial tension were investigated using the smoothed particle hydrodynamics model. Numerical simulations were performed using a discrete-element-type method that could track the movement of both the continuous liquid phase and the dispersed one directly. Numerical simulations were also performed for conditions corresponding to different interfacial tension and density values. Further, the predicted topological changes as well as the relationship between the physical properties and the droplet size distribution were investigated. It was found that, with an increase in the interfacial tension, the large droplets formed aggregate quickly with the bulk phase, owing to the buoyancy force. It was also found that the absolute value of the interfacial tension determines the interfacial area, suggesting that it also affects the droplet settling time. As such, we can conclude that the nonlinearly changed interface shape can easily become unstable as a result of only a slight change in the curvature.
• Nanostructural characterization of large-scale porous alumina fabricated via anodizing in arsenic acid solution

  Shunta Akiya, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  APPLIED SURFACE SCIENCE 403 652 - 661 0169-4332 2017/05 [Refereed][Not invited]
   

  Anodizing of aluminum in an arsenic acid solution is reported for the fabrication of anodic porous alumina. The highest potential difference (voltage) without oxide burning increased as the temperature and the concentration of the arsenic acid solution decreased, and a high anodizing potential difference of 340 V was achieved. An ordered porous alumina with several tens of cells was formed in 0.1-0.5 M arsenic acid solutions at 310-340 V for 20 h. However, the regularity of the porous alumina was not improved via anodizing for 72 h. No pore sealing behavior of the porous alumina was observed upon immersion in boiling distilled water, and it may be due to the formation of an insoluble complex on the oxide surface. The porous alumina consisted of two different layers: a hexagonal alumina layer that contained arsenic from the electrolyte and a pure alumina honeycomb skeleton. The porous alumina exhibited a white photoluminescence emission at approximately 515 nm under UV irradiation at 254 nm. (C) 2017 Elsevier B.V. All rights reserved.
• 1,10-Phenanthrolineを添加した1-ethyl-3-methylimidazolium chloride–AlCl3イオン液体中における光沢Alめっきの形成

  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 表面技術協会 68 (4) 208 - 212 0915-1869 2017 [Refereed][Not invited]
  
• Electrolytic reduction of V3S4 in molten CaCl2

  Takahiro Matsuzaki, Shungo Natsui, Tatsuya Kikuchi, Ryosuke O. Suzuki

  MATERIALS TRANSACTIONS 58 (3) 371 - 376 1345-9678 2017 [Refereed][Not invited]
   

  Metallic vanadium was successfully produced starting from vanadium sulfide by applying electrolysis in molten CaCl2. Vanadium sulfide filled in a cathodic Ti basket and a graphite anode were immersed in the melt of CaCl2-CaS at 1173 K in Ar, and the electrolysis was conducted at a cell voltage of 3.0 V. Sulfide electrolysis did not form carbon deposit and was free from carbon contamination, while carbon powder was formed on the cathode in the oxide electrolysis using the melt of CaCl2-CaO. When the CaS content in the molten CaCl2 increased, electrolysis current increased resulting in fast smelting while the oxygen and sulfur contents in metallic vanadium increased. Oxygen and sulfur contents as low as 3390 ppm and 210 ppm, respectively, were achieved by supplying about four times more electrical charge than stoichiometry.
• Calcium Reduction of TiS2 in CaCl2 Melt

  N. Suzuki, M. Tanaka, H. Noguchi, S. Natsui, T. Kikuchi, R. O. Suzuki

  MATERIALS TRANSACTIONS 58 (3) 367 - 370 1345-9678 2017 [Refereed][Not invited]
   

  In this study, we reduce TiS2 to Ti via both calciothermic reduction and electrolysis in a CaCl2 melt. Upon calcium reduction at 1133 K in CaCl2 melt, the concentration of sulfur decreases to 0.03 mass% S when an amount greater than twice the stoichiometric calcium amount is added. Upon electrolysis reduction at 1173 K in CaCl2-CaS melt, the concentration of sulfur initially decreases significantly to 0.01 mass% S when a sufficiently large amount of electric charge is supplied. Our results indicate that it is possible to achieve sulfur removal via both calciothermic reduction and electrochemical reaction.
• Reduction of CaTiO3 in Molten CaCl2 - as Basic Understanding of Electrolysis

  Ryosuke O. Suzuki, Hiromi Noguchi, Hiromasa Hada, Shungo Natsui, Tatsuya Kikuchi

  MATERIALS TRANSACTIONS 58 (3) 341 - 349 1345-9678 2017 [Refereed][Not invited]
   

  Electrochemical decomposition of CaTiO3 at the cathode was examined in a scheme of titanium metal production from natural deposit, Ilmenite (TiFeO3). Based on the possible precipitation of CaTiO3 from TiFeO3, the electrochemical decomposition of CaTiO3 is here examined using combination of the calciothermic reduction and the electrolysis of CaO in the same molten salt. Inhomogeneous reduction in the cathodic basket is related with buoyancy of Ca and insufficient dehydration. By optimizing the cooling conditions, CaO content in the molten salt, and dehydration method, an industrial level of 0.42 mass%O could be achieved as powder form.
• Observation of Interface Deformation in Sodium Polytungstate Solution-Silicone Oil System due to Single Rising Bubble

  Shungo Natsui, Ryota Nashimoto, Daiki Nakajima, Takehiko Kumagai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ISIJ INTERNATIONAL 57 (2) 394 - 396 0915-1559 2017 [Refereed][Not invited]
   

  The interfacial behavior between sodium polytungstate solution (SPTS) and silicone oil (SO) due to a single rising bubble was directly observed to investigate the influence of the Eotvos number on the flow characteristics. We found that the transient behavior of the jet under the bubble strongly depended on the SPTS density in the range of 1 000-3 000 kg/m(3). Although the SPTS film generated in the SO influenced the detention time of the jet under the bubble, the lifetime of the film did not depend on the SPTS density.
• Superhydrophilicity of a nanofiber-covered aluminum surface fabricated via pyrophosphoric acid anodizing

  Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  APPLIED SURFACE SCIENCE 389 173 - 180 0169-4332 2016/12 [Refereed][Not invited]
   

  A superhydrophilic aluminum surface covered by numerous alumina nanofibers was fabricated via pyrophosphoric acid anodizing. High-density anodic alumina nanofibers grow on the bottom of a honeycomb oxide via anodizing in concentrated pyrophosphoric acid. The water contact angle on the nanofiber-covered aluminum surface decreased with time after a 4 pi droplet was placed on the surface, and a superhydrophilic behavior with a contact angle measuring 2.2 was observed within 2 s; this contact angle is considerably lower than those observed for electropolished and porous alumina-covered aluminum surfaces. There was no dependence of the superhydrophilicity on the density of alumina nanofibers fabricated via different constant voltage anodizing conditions. The superhydrophilic property of the surface covered by anodic alumina nanofibers was maintained during an exposure test for 359 h. The quick-drying and snow-sliding behaviors of the superhydrophilic aluminum covered with anodic alumina nanofibers were demonstrated. (C) 2016 Elsevier B.V. All rights reserved.
• Fabrication of self-ordered porous alumina via anodizing in sulfate solutions

  Ryunosuke Kondo, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  MATERIALS LETTERS 183 285 - 289 0167-577X 2016/11 [Refereed][Not invited]
   

  Self-ordered porous alumina was fabricated via anodizing in an acid salt electrolyte solution, sodium hydrogen sulfate (NaHSO4). High-purity aluminum specimens were anodized in a NaHSO4 solution under various operating conditions with adjusted concentrations, temperatures, applied voltages, and times. Self-ordering was achieved via NaHSO4 anodizing at appropriate applied voltages ranging from 20 to 28 V, and ordered cell arrangements with the cell size of 55-77 nm were successfully fabricated. Sulfur atoms originating from the electrolyte anions were incorporated into the ordered porous alumina. A honeycomb distribution consisting of a thick outer layer with a high concentration of sulfur and a very thin inner skeleton with a relatively low concentration sulfur was formed via NaHSO4 anodizing. Our results suggested that there are now many electrolyte options for the fabrication of self-ordered porous alumina with a wide range of nanosizes. (C) 2016 Elsevier B.V. All rights reserved.
• Exploration for the Self-ordering of Porous Alumina Fabricated via Anodizing in Etidronic Acid

  Akimasa Takenaga, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 211 515 - 523 0013-4686 2016/09 [Refereed][Not invited]
   

  Ordered porous alumina (OPA) with large-scale circular and hexagonal pores was fabricated via etidronic acid anodizing. High-purity aluminum plates were anodized in 0.2-4.2 M etidronic acid solution at 145-310 V and 288-323 K. Self-ordering of porous alumina was observed at 165 V and 313 K in 4.2 M, at 205 V and 303 K in 1.0 M, and at 260 V and 298 K in 0.2 M, and the cell diameter was measured to be 400-640 nm. The ordering potential difference decreased with the electrolyte concentration increasing. OPA without an intercrossing nanostructure could be fabricated on a nanostructured aluminum surface via two-step anodizing. Subsequent pore-widening in etidronic acid solution caused the circular dissolution of anodic oxide and the expansion of pore diameters to 470 nm. The shape of the pores was subsequently changed to a hexagon from a circle via long-term pore-widening, and a honeycomb structure with narrow alumina walls and hexagonal pores measuring 590 nm in its long-axis was formed in the porous alumina. Transition of the nanostructure configuration during pore-widening corresponded to differences in the incorporated phosphorus distribution originating from the etidronic acid anions. (C) 2016 Elsevier Ltd. All rights reserved.
• Temperature Dependence of Behavior of Interface Between Molten Sn and LiCl-KCl Eutectic Melt Due to Rising Gas Bubble

  Shungo Natsui, Ryota Nashimoto, Hifumi Takai, Takehiko Kumagai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE 47 (3) 1532 - 1537 1073-5615 2016/06 [Refereed][Not invited]
   

  The behavior of the interface between molten Sn and the LiCl-KCl eutectic melt system was observed directly. We found that the transient behavior of the interface exhibits considerable temperature dependence through a change in its physical properties. The "metal film" generated in the upper molten salt phase significantly influences the shape of the interface. Although the lifetime of the metal film depends on the gas flow rate, it is not affected by the buoyancy if the interfacial tension is dominant. (C) The Minerals, Metals & Materials Society and ASM International 2016
• Self-ordered Porous Alumina Fabricated via Phosphonic Acid Anodizing

  Shunta Akiya, Tatsuya Kikuchi, Shungo Natsui, Norihito Sakaguchi, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 190 471 - 479 0013-4686 2016/02 [Refereed][Not invited]
   

  Self-ordered periodic porous alumina with an undiscovered cell diameter was fabricated via electrochemical anodizing in a new electrolyte, phosphonic acid (H3PO3). High-purity aluminum plates were anodized in phosphonic acid solution under various operating conditions of voltage, temperature, concentration, and anodizing time. Phosphonic acid anodizing at 150-180 V caused the self-ordering behavior of porous alumina, and an ideal honeycomb nanostructure measuring 370-440 nm in cell diameter was successfully fabricated on the aluminum substrate. Conversely, disordered porous alumina grew at below 140 V, and anodizing at above 190 V caused local thickening due to oxide burning. Two-step phosphonic acid anodizing allows the fabrication of high aspect ratio ordered porous alumina. HPO32 anions originated from the electrolyte were incorporated into the porous oxide during anodizing. Consequently, a double-layered porous alumina consisting of a thick outer layer containing incorporated HPO32 anions, and a thin inner layer without anions was constructed via phosphonic acid anodizing. (C) 2015 Elsevier Ltd. All rights reserved.
• SPH simulations of the behavior of the interface between two immiscible liquid stirred by the movement of a gas bubble

  Shungo Natsui, Ryota Nashimoto, Hifumi Takai, Takehiko Kumagai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  CHEMICAL ENGINEERING SCIENCE 141 342 - 355 0009-2509 2016/02 [Refereed][Not invited]
   

  The transient behavior of the immiscible two liquids interface, which is initiated by the rising gas bubble was investigated using Smoothed Particle Hydrodynamics (SPH) model. This developed numerical method is using fully Lagrangian particle-based model, which can track the movement of both the gas and the liquid phase directly. Numerical simulations have been performed for different conditions corresponding to different values of surface tension, viscosity and density, and the predicted topological changes as well as the theoretical pressure and interfacial shape of bubbles are validated. In the case of immiscible two liquids, the column of a lower liquid phase penetrating into the upper liquid phase influences interface area, whose shape strongly depends on the wake flow pattern of a bubble. Thus, the dynamic balance between the buoyancy and the liquid-liquid interfacial tension determines an interface area. Under higher surface tension condition, such as molten metal-slag system, the liquid-liquid interface shape is greatly influenced by the fluctuation of a bubble. Then, nonlinearly changed interface shape can be observed, indicating that this shape becomes easily unstable by slight change of the curvature. (C) 2015 Elsevier Ltd. All rights reserved.
• アノード酸化によるアルミナナノファイバーの作製と表面機能化

  菊地竜也, 中島大希, 夏井俊悟, 鈴木亮輔

  表面技術 67 527 - 532 2016 [Refereed][Invited]
  
• Model study of the effect of particles structure on the heat and mass transfer through the packed bed in ironmaking blast furnace

  Shungo Natsui, Hifumi Takai, Ryota Nashimoto, Tatsuya Kikuchi, Ryosuke O. Suzuki

  INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 91 1176 - 1186 0017-9310 2015/12 [Refereed][Not invited]
   

  Ironmaking technology is currently focused on the introduction of the decreased reducing agent operation of a blast furnace in order to decrease CO2 emissions. Because the coke ratio is reduced in this operation, causing a huge pressure drop, it has become increasingly important to understand the in-furnace phenomena using the non-empirical method. In this study, the DEM-CFD simulation was carried out to analyze the heat and mass transfer between the gaseous phase and the particles in a packed bed. In particular, the effect of recently proposed helical structure of coke and ore layers was compared with the traditional layer-by-layer structure. This comparison shows that the helical structure is effective for the smooth gas flow in the packed bed. It was found that the increase of the gas flow rate in a large grain size coke layer, would not affect the total permeability of the packed bed. Since the helical structure decreases the amount of inflow of the gaseous phase to the ore bed, the reduction rate of this ore tends to decrease the thickness of the layered structure, but this effect is relatively small. The helical structure becomes more permeable, if a thicker layer is maintained even under the decreased coke ratio condition. (C) 2015 Elsevier Ltd. All rights reserved.
• Fabrication of a novel aluminum surface covered by numerous high-aspect-ratio anodic alumina nanofibers

  Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Norihito Sakaguchi, Ryosuke O. Suzuki

  APPLIED SURFACE SCIENCE 356 54 - 62 0169-4332 2015/11 [Refereed][Not invited]
   

  The formation behavior of anodic alumina nanofibers via anodizing in a concentrated pyrophosphoric acid under various conditions was investigated using electrochemical measurements and SEM/TEM observations. Pyrophosphoric acid anodizing at 293 K resulted in the formation of numerous anodic alumina nanofibers on an aluminum substrate through a thin barrier oxide and honeycomb oxide with narrow walls. However, long-term anodizing led to the chemical dissolution of the alumina nanofibers. The density of the anodic alumina nanofibers decreased as the applied voltage increased in the 10-75 V range. However, active electrochemical dissolution of the aluminum substrate occurred at a higher voltage of 90V. Low temperature anodizing at 273 K resulted in the formation of long alumina nanofibers measuring several micrometers in length, even though a long processing time was required due to the low current density during the low temperature anodizing. In contrast, high temperature anodizing easily resulted in the formation and chemical dissolution of alumina nanofibers. The structural nanofeatures of the anodic alumina nanofibers were controlled by choosing of the appropriate electrochemical conditions, and numerous high-aspect-ratio alumina nanofibers (>100) can be successfully fabricated. The anodic alumina nanofibers consisted of a pure amorphous aluminum oxide without anions from the employed electrolyte. (C) 2015 Elsevier B.V. All rights reserved.
• Polymer nanoimprinting using an anodized aluminum mold for structural coloration

  Tatsuya Kikuchi, Osamu Nishinaga, Shungo Natsui, Ryosuke O. Suzuki

  APPLIED SURFACE SCIENCE 341 19 - 27 0169-4332 2015/06 [Refereed][Not invited]
   

  Polymer nanoimprinting of submicrometer-scale dimple arrays with structural coloration was demonstrated. Highly ordered aluminum dimple arrays measuring 530-670 nm in diameter were formed on an aluminum substrate via etidronic acid anodizing at 210-270 V and subsequent anodic oxide dissolution. The nanostructured aluminum surface led to bright structural coloration with a rainbow spectrum, and the reflected wavelength strongly depends on the angle of the specimen and the period of the dimple array. The reflection peak shifts gradually with the dimple diameter toward longer wavelength, reaching 800 nm in wavelength at 670 nm in diameter. The shape of the aluminum dimple arrays were successfully transferred to a mercapto-ester ultra-violet curable polymer via self-assembled monolayer coating and polymer replications using a nanoimprinting technique. The nanostructured polymer surfaces with positively and negatively shaped dimple arrays also exhibited structural coloration based on the periodic nanostructure, and reflected light mostly in the visible region, 400-800 nm. This nanostructuring with structural coloration can be easily realized by simple techniques such as anodizing, SAM coating, and nanoimprinting. (C) 2015 Elsevier B.V. All rights reserved.
• Niobium powder synthesized by calciothermic reduction of niobium hydroxide for use in capacitors

  Masahiko Baba, Tatsuya Kikuchi, Ryosuke O. Suzuki

  JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS 78 101 - 109 0022-3697 2015/03 [Refereed][Not invited]
   

  Metallic niobium powder was produced for applications in electric capacitors via calciothermic reduction of niobium hydroxide in molten CaCl2. Sub-micrometer spherical metallic particles with coral-like morphologies reflected the particle size of the starting oxide powder. A fine powder was obtained from the mixtures of niobium hydroxide and CaO or Ca(OH)(2), respectively. Sintered pellets of the metallic powder showed a higher capacitance (CV) than those of the simply reduced powder without pre-treatment, because the shrinkage during sintering was smaller. The CV was as large as that of commercially sintered pellets for tantalum capacitors. Therefore, this niobium powder would act as a higher-voltage capacitor by applying chemical anodic treatment at higher voltages, and lower oxygen content in the reduced power could realize a lower leak current. (C) 2014 Elsevier Ltd. All rights reserved.
• Fabrication of Self-Ordered Porous Alumina via Etidronic Acid Anodizing and Structural Color Generation from Submicrometer-Scale Dimple Array

  Tatsuya Kikuchi, Osamu Nishinaga, Shungo Natsui, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 156 235 - 243 0013-4686 2015/02 [Refereed][Not invited]
   

  Highly ordered anodic porous alumina with a large-scale cell diameter was successfully fabricated via anodizing in a new electrolyte, etidronic acid (1-hydroxyethane-1,1-diphosphonic acid). High-purity aluminum specimens were anodized in a 0.3 M etidronic acid solution under constant current density and voltage conditions. Etidronic acid anodizing at 210 to 270 V at the appropriate temperature caused the anodic porous alumina to exhibit self-ordering behavior, and periodic nanostructures measuring 530 to 670 nm in cell diameter were fabricated on the aluminum substrate. The self-ordering voltage and the corresponding cell diameter could be increased without burning by systematically increasing the stepwise voltage. Two-step etidronic acid anodizing without nanoimprinting can easily yield the formation of highly ordered anodic porous alumina with a large-scale cell diameter. A submicrometers-cale dimple array fabricated via etidronic acid anodizing and subsequent selective oxide dissolution gave rise to bright structural color with a rainbow distribution. (C) 2015 Elsevier Ltd. All rights reserved.
• Euler-Lagrange法による高炉モデル

  夏井俊悟, 菊地竜也, 鈴木亮輔

  まてりあ 54 432 - 435 2015 [Not refereed][Invited]
  
• Optimum Exploration for the Self-Ordering of Anodic Porous Alumina Formed via Selenic Acid Anodizing

  Shunta Akiya, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  Journal of The Electrochemical Society Electrochemical Society 162 (10) E244 - E250 0013-4651 2015 [Refereed][Not invited]
   

  Improvements of the regularity of the arrangement of anodic porous alumina formed by selenic acid anodizing were investigated under various operating conditions. The oxide burning voltage increased with the stirring rate of the selenic acid solution, and the high applied voltage without oxide burning was achieved by vigorously stirring the solution. The regularity of the porous alumina was improved as the anodizing time and surface flatness increased. Conversely, the purity of the 99.5–99.9999 wt% aluminum specimens without second phases of metals and metallic compounds was not affected by the regularity of the porous alumina formed by selenic acid anodizing. The porous alumina was also self-ordered on/around a defect, such as a grain boundary, under self-ordering high voltage anodizing conditions. A highly ordered cell arrangement measuring 111 nm in diameter was successfully fabricated over the whole aluminum surface by selenic acid anodizing using a 99.999 wt% aluminum plate at 273 K and 46 V for 24 h under vigorous stirring conditions.
• Carbon Nanotube Synthesis via the Calciothermic Reduction of Carbon Dioxide with Iron Additives

  Tatsuya Kikuchi, Ryoma Ishida, Shungo Natsui, Takehiko Kumagai, Isao Ogino, Norihito Sakaguchi, Mikito Ueda, Ryosuke O. Suzuki

  ECS Solid State Letters Electrochemical Society 4 (9) M19 - M22 2162-8742 2015 [Refereed][Not invited]
   

  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.
• Porous Aluminum Oxide Formed by Anodizing in Various Electrolyte Species

  Tatsuya Kikuchi, Daiki Nakajima, Osamu Nishinaga, Shungo Natsui, Ryosuke O. Suzuki

  CURRENT NANOSCIENCE 11 (5) 560 - 571 1573-4137 2015 [Refereed][Invited]
   

  Anodizing of aluminum and its alloys is widely investigated and used for corrosion protection, electronic devices, and micro-/nanostructure fabrication. Anodizing of aluminum in acidic solutions causes formation of porous aluminum oxide films, which consists of numerous hexagonal cells perpendicular to the aluminum substrate, and each cell has nanoscale pores at its center. Recently, highly ordered porous aluminum oxide has been widely investigated for various novel nanoapplications. In this review article, we introduce the fundamentals of anodic oxide films including barrier and porous oxides. Then, we summarize the electrolyte species used so far for porous oxide fabrication and describe the self-ordering conditions during anodizing in these electrolyte solutions. Fabrication of highly ordered porous oxides through the vertical section can be achieved by a two-step anodizing and nanoimprint technique. Various nanoapplications based on the ordered porous oxide are also introduced.
• Characterization of Liquid Trickle Flow in Poor-Wetting Packed Bed

  Shungo Natsui, Tatsuya Kikuchi, Ryosuke O. Suzuki, Tatsuya Kon, Shigeru Ueda, Hiroshi Nogami

  ISIJ International The Iron and Steel Institute of Japan 55 (6) 1259 - 1266 0915-1559 2015 [Refereed][Not invited]
   

  A low coke rate operation of a blast furnace tends to cause deterioration of the gas permeability. The liquid iron and molten slag dripping under the melting zone influences the gas flow and permeability in the lower part of the furnace. A computational fluid dynamic model, using a particle-based simulation, is presented for characterization of the melt dripping behavior in a packed bed. In this work, the validity of the liquid passing conditions based on the gravity to surface tension ratio was confirmed. The melt shape produces an "icicle," "droplet," and "dome" forms based on the change of the surface tension and density absolute values. Even with an identical liquid volume passage, the form of the liquid flow changed by the pressure from the liquid's upper portion. Even if it has identical gravity and surface tension ratios, the liquid flow changes with the volume of the liquid phase and its form.
• Self-ordered Aluminum Anodizing in Phosphonoacetic Acid and Its Structural Coloration

  Akimasa Takenaga, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  ECS Solid State Letters 4 (8) P55 - P58 2162-8742 2015 [Refereed][Not invited]
   

  Ordered anodic porous alumina with large-scale periodicity was fabricated via phosphonoacetic acid anodizing. Aluminum specimens were anodized in a 0.1–0.9 M phosphonoacetic acid solution under various electrochemical operating conditions, and optimum anodizing at 205–225 V exhibited self-ordering growth of the porous alumina. These self-ordering voltages during phosphonoacetic acid anodizing filled an undiscovered vacant region in the linear relationship between the self-ordering voltage and the cell diameter. The nanostructured aluminum surface formed via self-ordering phosphonoacetic acid anodizing produced a bright structural coloration with a visible light wavelength of 500–700 nm, which is useful for optical nanoapplications.
• Highly Ordered Anodic Alumina Nanofibers Fabricated via Two Distinct Anodizing Processes

  Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  ECS Electrochemistry Letters The Electrochemical Society 4 (5) H14 - H17 2162-8726 2015 [Refereed][Not invited]
   

  Fabrication of high-density, highly ordered anodic alumina nanofibers was demonstrated via two distinct anodizing processes: porous and fibrous oxide formations. Highly ordered aluminum dimple arrays were fabricated via sulfuric/oxalic acid anodizing and selective porous alumina dissolution. Subsequent pyrophosphoric acid anodizing using the nanostructured aluminum surface caused anodic alumina nanofibers to grow preferentially at the six apexes of the ordered hexagonal aluminum dimples under the appropriate electrochemical conditions. Well-defined, high-density, highly ordered anodic alumina nanofibers with 37–75 nm periodic spacing and at densities of 1.4–5.6 × 1014 m−2 were successfully fabricated on the aluminum surface via two distinct anodizing processes.
• CO Gas Production by Molten Salt Electrolysis from CO2 Gas

  Fumiya Matsuura, Takafumi Wakamatsu, Shungo Natsui, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ISIJ INTERNATIONAL 55 (2) 404 - 408 0915-1559 2015 [Refereed][Not invited]
   

  CO2 gas is decomposed to CO and C by the molten salt electrolysis using CaCl2-CaO and solid state electrolyte, zirconia, as the anode. Partially CO2 gas dissolves to form CO32- and it is electrochemically decomposed to carbon. The other portion of CO2 gas bubbles reacts with metallic Ca electrochemically deposited near the cathode, and forms C or CO gas. By increasing the flow rate of CO2 gas to the reactor, a high concentration of CO gas is generated. By increasing the concentration of CO2 gas in the initial gas, a large amount of CO gas was produced in the exhaust gas, and its rate approached to 3.32x10(-8) m(3)/s in our experimental setup. These experimental evidences reflect the electrochemical decomposition of CO32- in the molten salt.
• Solubility of gaseous carbon dioxide in molten LiCL-Li2O

  Takafumi Wakamatsu, Takuya Uchiyama, Shungo Natsui, Tatsuya Kikuchi, Ryosuke O. Suzuki

  FLUID PHASE EQUILIBRIA 385 48 - 53 0378-3812 2015/01 [Refereed][Not invited]
   

  Carbonate ions in LiCL-Li2O salt are a source of carbon contamination in the electrolytic refining of metal oxides, and their concentration is also an essential information for understanding the CO2 decomposition process. In this study, the solubility of gaseous CO2 in molten LiCI-Li2O was studied with the goal of developing processes to decompose the oxides effectively. Ar-CO2 gas mixtures were dissolved in molten salts containing various amounts of Li2O, and the solubility of the CO2 gas was calculated by measuring the mass difference between the molten salts before and after the CO2 dissolution. The molar amount of dissolved CO2 gas was almost as large as the molar quantity of Li2O when the partial pressure of CO2 was 1.0 or 0.5 atm for Li2O concentrations in the range of 0-60 mol%. This confirms that a large quantity of the oxide ions reacted with the CO2 gas, resulting in the generation of carbonate ions. (C) 2014 Published by Elsevier B.V.
• Growth behavior of anodic oxide formed by aluminum anodizing in glutaric and its derivative acid electrolytes

  Daiki Nakajima, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  APPLIED SURFACE SCIENCE 321 364 - 370 0169-4332 2014/12 [Refereed][Not invited]
   

  The growth behavior of anodic oxide films formed via anodizing in glutaric and its derivative acid solutions was investigated based on the acid dissociation constants of electrolytes. High-purity aluminum foils were anodized in glutaric, ketoglutaric, and acetonedicarboxylic acid solutions under various electrochemical conditions. A thin barrier anodic oxide film grew uniformly on the aluminum substrate by glutaric acid anodizing, and further anodizing caused the film to breakdown due to a high electric field. In contrast, an anodic porous alumina film with a submicrometer-scale cell diameter was successfully formed by ketoglutaric acid anodizing at 293 K. However, the increase and decrease in the temperature of the ketoglutaric acid resulted in non-uniform oxide growth and localized pitting corrosion of the aluminum substrate. An anodic porous alumina film could also be fabricated by acetonedicarboxylic acid anodizing due to the relatively low dissociation constants associated with the acid. Acid dissociation constants are an important factor for the fabrication of anodic porous alumina films. (C) 2014 Elsevier B.V. All rights reserved.
• Numerical Analysis of Carbon Monoxide-Hydrogen Gas Reduction of Iron Ore in a Packed Bed by an Euler-Lagrange Approach

  Shungo Natsui, Tatsuya Kikuchi, Ryosuke O. Suzuki

  METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE 45 (6) 2395 - 2413 1073-5615 2014/12 [Refereed][Not invited]
   

  In recent years, various methods to decrease carbon dioxide emissions from iron and steel making industries have been developed. The latest blast furnace operation design is intended to induce the low reducing agent operation, highly reactive material is considered a promising way to improve reaction efficiency. Another method utilizes hydrogen in the blast furnace process for highly efficient reduction. Mathematical modeling may help to predict complex in-furnace phenomena, including momentum, heat, and mass transport. However, the current macroscopic continuum model gives no information on the individual particles. In this work, a new approach based on the discrete element method was introduced to consider the interaction between particles under fluid flow in accordance with the arrangement and properties of individual particles. We used an Euler-Lagrange method to precisely understand the influence of the reaction conditions on the behavior of coke and ore particles in three dimensions. The heterogeneity of the reaction rate and temperature distribution was observed to be influenced by the particle arrangement. The endothermic and exothermic reactions influenced each other in the packed bed. Temperature distributions nearly correlated with the gas velocity distribution because convection processes greatly affected the reaction rate. Although convection heat transfer was not a dominant issue in the packed bed, promotion of the reaction by a gas flow was effective.
• Fabrication of anodic porous alumina via anodizing in cyclic oxocarbon acids

  Tatsuya Kikuchi, Daiki Nakajima, Jun Kawashima, Shungo Natsui, Ryosuke O. Suzuki

  APPLIED SURFACE SCIENCE 313 276 - 285 0169-4332 2014/09 [Refereed][Not invited]
   

  The growth behavior of anodic porous alumina formed by anodizing in novel electrolyte solutions, the cyclic oxocarbon acids croconic and rhodizonic acid, was investigated for the first time. High-purity aluminum specimens were anodized in 0.1 M croconic and rhodizonic acid solutions at various constant current densities. An anodic porous alumina film with a cell size of 200-450 nm grew uniformly on an aluminum substrate by rhodizonic acid anodizing at 5-40 A m(-2), and a black, burned oxide was formed at higher current density. The cell size of the porous alumina increased with current density and corresponding anodizing voltage. Anodizing in croconic acid at 293 K caused the formation of thin anodic porous alumina films as well as black, thick burned oxides. The uniformity of the porous alumina improved by increasing the temperature of the croconic acid solution, and anodic porous alumina films with a uniform film thickness were successfully obtained. Our experimental results showed that the cyclic oxocarbon acids croconic and rhodizonic acid could be employed as a suitable electrolyte for the formation of anodic porous alumina films. (C) 2014 Elsevier B.V. All rights reserved.
• Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

  Tatsuya Kikuchi, Masumi Yoshida, Shiki Matsuura, Shungo Natsui, Etsuji Tsuji, Hiroki Habazaki, Ryosuke O. Suzuki

  JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS 75 (9) 1041 - 1048 0022-3697 2014/09 [Refereed][Not invited]
   

  Micro-, submicron-, and nano-scale titanium dioxide particles were reduced by reduction with a metallic calcium reductant in calcium chloride molten salt at 1173 K, and the reduction mechanism of the oxides by the calcium reductant was explored. These oxide particles, metallic calcium as a reducing agent, and calcium chloride as a molten salt were placed in a titanium crucible and heated under an argon atmosphere. Titanium dioxide was reduced to metallic titanium through a calcium titanate and lower titanium oxide, and the materials were sintered together to form a micro-porous titanium structure in molten salt at high temperature. The reduction rate of titanium dioxide was observed to increase with decreasing particle size; accordingly, the residual oxygen content in the reduced titanium decreases. The obtained micro-porous titanium appeared dark gray in color because of its low surface reflection. Microporous metallic titanium with a low oxygen content (0.42 wt%) and a large surface area (1.794 m(2) g(-1)) can be successfully obtained by reduction under optimal conditions. (C) 2014 Elsevier Ltd. All rights reserved.
• Self-Ordering Behavior of Anodic Porous Alumina via Selenic Acid Anodizing

  Tatsuya Kikuchi, Osamu Nishinaga, Shungo Natsui, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 137 728 - 735 0013-4686 2014/08 [Refereed][Not invited]
   

  The self-ordering behavior of anodic porous alumina that was formed by anodizing in selenic acid electrolyte (H2SeO4) at various concentrations and voltages was investigated with SEM and AFM imaging. A high purity aluminum foil was anodized in 0.1-3.0M selenic acid solutions at 273 K and at constant cell voltages in the range of 37 to 51V. The regularity of the cell arrangement increased with increasing anodizing voltage and selenic acid concentration under conditions of steady oxide growth without burning. Anodizing at 42-46V in 3.0M selenic acid produced highly ordered porous alumina. By selective dissolution of the anodic porous alumina, highly ordered convex nanostructures of aluminum with diameters of 20nm and heights of 40nm were exposed at the apexes of each hexagonal dimple array. Highly ordered anodic porous alumina with a cell size of 102nm from top to bottom can be fabricated by a two-step selenic acid anodizing process, that includes the first anodizing step, the selective oxide dissolution, and the second anodizing step. (C) 2014 Elsevier Ltd. All rights reserved.
• Fabrication of Anodic Porous Alumina by Squaric Acid Anodizing

  Tatsuya Kikuchi, Tsuyoshi Yamamoto, Shungo Natsui, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 123 14 - 22 0013-4686 2014/03 [Refereed][Not invited]
   

  The growth behavior of anodic porous alumina formed via anodizing in a new electrolyte, squaric acid (3,4-dihydroxy-3-cyclobutene-1,2-dione), is reported for the first time. A high-purity aluminum foil was anodized in a 0.1 M squaric acid solution at 293 K and a constant applied potential of 100-150 V. Anodic oxides grew on the aluminum foil at applied potentials of 100-120 V, but a burned oxide film was formed at higher voltage. Anodic porous alumina with a cell size of approximately 200-400 nm and sub-100-nm-scale pore diameter was successfully fabricated by anodizing in squaric acid. The cell size of the anodic oxide increased with anodizing time because of the uneven growth of the porous layer. The anodic porous alumina obtained by squaric acid anodizing consists of amorphous Al2O3 containing 5-6 at% carbon from the electrolyte. (C) 2014 Elsevier Ltd. All rights reserved.
• Fabrication of a micro-porous Ti-Zr alloy by electroless reduction with a calcium reductant for electrolytic capacitor applications

  Tatsuya Kikuchi, Masumi Yoshida, Yoshiaki Taguchi, Hiroki Habazaki, Ryosuke O. Suzuki

  JOURNAL OF ALLOYS AND COMPOUNDS 586 148 - 154 0925-8388 2014/02 [Refereed][Not invited]
   

  A metallic titanium and zirconium micro-porous alloy for electrolytic capacitor applications was produced by electroless reduction with a calcium reductant in calcium chloride molten salt at 1173 K. Mixed TiO2-70 at%ZrO2 oxides, metallic calcium, and calcium chloride were placed in a titanium crucible and heated under argon atmosphere to reduce the oxides with the calcium reductant. A metallic Ti-Zr alloy was obtained by electroless reduction in the presence of excess calcium reductant and showed a microporous morphology due to the sintering of each of the reduced particles during the reduction. The residual oxygen content and surface area of the reduced Ti-Zr alloy decreased over time during the electroless reduction. The element distributions were slightly different at the positions of the alloy and were in the composition range of Ti-69.3 at% to 74.3 at% Zr. A micro-porous Ti-Zr alloy with low oxygen content (0.20 wt%) and large surface area (0.55 m(2) g (1)) was successfully fabricated by electroless reduction under optimal conditions. The reduction mechanisms of the mixed and pure oxides by the calcium reductant are also discussed. (C) 2013 Elsevier B. V. All rights reserved.
• Fabrication of Anodic Nanoporous Alumina via Acetylenedicarboxylic Acid Anodizing

  Tatsuya Kikuchi, Osamu Nishinaga, Shungo Natsui, Ryosuke O. Suzuki

  ECS Electrochemistry Letters The Electrochemical Society 3 (7) C25 - C28 2162-8726 2014 [Refereed][Not invited]
   

  The nano-morphologies of anodic porous alumina formed via anodizing in a newelectrolyte, acetylenedicarboxylic acid (ADCA), are described. Anodic oxides grewuniformly on the aluminum at voltage of 87.5-95.0 V, but a burned black oxide filmwas formed at higher voltage. The burning voltage and the current density understeady-state oxide growth decreased with solution temperature. An anodic porousalumina film with a cell size of 250 nm and nanopores measuring 100 nm could besuccessfully obtained by ADCA anodizing. The anodic porous alumina possessednumerous non-straight nanopores due to the branching and extinction of the nanoporesduring anodizing.
• Stable Mesh-free Particle Simulation for Direct Analysis of Gas-Liquid Two-Phase Flow

  Shungo Natsui, Hifumi Takai, Takehiko Kumagao, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Chemical Engineering Science 111 286 - 298 2014 [Refereed][Not invited]
  
• Ultra-High Density Single Nanometer-Scale Anodic Alumina Nanofibers Fabricated by Pyrophosphoric Acid Anodizing

  Tatsuya Kikuchi, Osamu Nishinaga, Daiki Nakajima, Jun Kawashima, Shungo Natsui, Norihito Sakaguchi, Ryosuke O. Suzuki

  Scientific Reports Nature Publishing Group 4 7411 - 7411 2045-2322 2014 [Refereed][Not invited]
   

  Anodic oxide fabricated by anodizing has been widely used for nanostructural engineering, but the nanomorphology is limited to only two oxides: anodic barrier and porous oxides. Therefore, the discovery of an additional anodic oxide with a unique nanofeature would expand the applicability of anodizing. Here we demonstrate the fabrication of a third-generation anodic oxide, specifically, anodic alumina nanofibers, by anodizing in a new electrolyte, pyrophosphoric acid. Ultra-high density single nanometer-scale anodic alumina nanofibers (1010 nanofibers/cm(2)) consisting of an amorphous, pure aluminum oxide were successfully fabricated via pyrophosphoric acid anodizing. The nanomorphologies of the anodic nanofibers can be controlled by the electrochemical conditions. Anodic tungsten oxide nanofibers can also be fabricated by pyrophosphoric acid anodizing. The aluminum surface covered by the anodic alumina nanofibers exhibited ultra-fast superhydrophilic behavior, with a contact angle of less than 16, within 1 second. Such ultra-narrow nanofibers can be used for various nanoapplications including catalysts, wettability control, and electronic devices.
• Multiphase Particle Simulation of Gas Bubble Passing Through Liquid/Liquid Interfaces

  Shungo Natsui, Hifumi Takai, Takehiko Kumagai, Tatsuya Kikuchi, Ryosuke O. Suzuki

  MATERIALS TRANSACTIONS 55 (11) 1707 - 1715 1345-9678 2014 [Refereed][Not invited]
   

  A newly developed computational fluid dynamics (CFD) model based on a multi-phase particle method is presented for predicting the entrainment behavior of liquid metal into slag due to rising single bubble. By comparing results calculated using this model against experimental data, it was found that the transient behavior of bubbles and the two immiscible liquids can be accurately estimated by this method. The rupturing of the thin water film surrounding the bubble was less reliably predicted, but this 3-dimensional unsteady numerical model still nevertheless provides valuable new information for directly predicting the change in the liquid/liquid interface over time. Such prediction of continuous change in an interface has not been possible by more conventional methods, and thus further improvement in the accuracy of this simulated model may well be the only way to non-empirically predict the metal-slag interface area in actual processes.
• Porous anodic oxide films on aluminum and their nanofabrication

  Tatsuya Kikuchi, Daiki Nakajima, Osamu Nishinaga, Shungo Natsui, Ryosuke O. Suzuki

  Keikinzoku/Journal of Japan Institute of Light Metals 64 (10) 476 - 482 0451-5994 2014 [Not refereed][Invited]
  
• Aluminum bulk micromachining through an anodic oxide mask by electrochemical etching in an acetic acid/perchloric acid solution

  Tatsuya Kikuchi, Yuhta Wachi, Masatoshi Sakairi, Ryosuke O. Suzuki

  MICROELECTRONIC ENGINEERING 111 14 - 20 0167-9317 2013/11 [Refereed][Not invited]
   

  A well-defined microstructure with microchannels and a microchamber was fabricated on an aluminum plate by four steps of a new aluminum bulk micromachining process: anodizing, laser irradiation, electrochemical etching, and ultrasonication. An aluminum specimen was anodized in an oxalic acid solution to form a porous anodic oxide film. The anodized aluminum specimen was irradiated with a pulsed Nd-YAG laser to locally remove the anodic oxide film, and then the exposed aluminum substrate was selectively dissolved by electrochemical etching in an acetic acid/perchloric acid solution. The anodic oxide film showed good insulating properties as a resist mask during electrochemical etching in the solution. A hemicylindrical microgroove with thin free-standing anodic oxide on the groove was fabricated by electrochemical etching, and the groove showed a smooth surface with a calculated mean roughness of 0.2-0.3 mu m. The free-standing oxides formed by electrochemical etching were easily removed from the specimen by ultrasonication in an ethanol solution. Microchannels 60 mu m in diameter and 25 mu m in depth connected to a microchamber were successfully fabricated on the aluminum. (C) 2013 Elsevier B.V. All rights reserved.
• Formation of alumina films with nano-dot structures by successive liquid phase deposition, anodizing, and substrate dissolution

  M. Sakairi, R. Fujita, H. Jha, T. Kikuchi

  SURFACE AND INTERFACE ANALYSIS 45 (10) 1510 - 1516 0142-2421 2013/10 [Refereed][Not invited]
   

  A process based on successive anodizing, liquid phase deposition (LPD), re-anodizing, and aluminium substrate dissolution to form alumina films with nano-dot structures is demonstrated. Initially, a protective oxide film is formed on the aluminium surface to prevent further dissolution of the aluminium substrate during LPD processing. Because of heterogeneity in the protective oxide film, localized dissolution would otherwise occur under the film, resulting in pit formation during the LPD treatment. During re-anodizing, these pits act as a mold for anodic oxide resembling a nano-dot like structure. Optimization of LPD parameters, such as time and temperature, would make it possible to obtain alumina films with nano-dot structures with sizes smaller than 1 mu m. Alumina films with nano-dot structures with hollow can be realized by controlling the LPD conditions. Copyright (c) 2013 John Wiley & Sons, Ltd.
• CO2 gas decomposition to carbon by electro-reduction in molten salts

  Koya Otake, Hiroshi Kinoshita, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 100 293 - 299 0013-4686 2013/06 [Refereed][Not invited]
   

  The electrochemical decomposition of CO2 gas in LiCl-Li2O or CaCl2-CaO molten salt was studied to produce carbon. This process consists of the electrochemical reduction of the oxide, Li2O or CaO, and the thermal reduction of CO2 gas by metallic Li or Ca. Two kinds of ZrO2 solid electrolytes were tested as an oxygen ions conductor and removed oxygen ions from the molten salts to the outside of reactor. After the electrolysis in the both salts, the aggregations of nanometer-scale amorphous carbon and rodlike graphite crystals were observed by transmission electron microscope. When 9.7% CO2 Ar mixed gas was blown into LiCl-Li2O or CaCl2-CaO molten salt, the current efficiency was evaluated to be 89.7% or 78.5%, respectively, by the exhaust gas analysis and the supplied charge. When the solid electrolyte with the better ionic conductivity was used, the current and the carbon production became larger. The rate determining step of this proposal was diffusion of oxygen ions in ZrO2 solid electrolyte. 2013 Elsevier Ltd. All rights reserved.
• Formation of niobium powder by electrolysis in molten salt

  Isamu Ueda, Masahiko Baba, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 100 269 - 274 0013-4686 2013/06 [Refereed][Not invited]
   

  Fine Nb2O5 powder was filled into a basket-type cathode and immersed in molten CaCl2-0.5 mol% CaO at 1173K. Nb2O5 immediately reacted with CaO in the molten CaCl2 and formed calcium niobites that exhibited rod- or plate-like morphology. After the electrolysis of CaO with a graphite consumable anode, spherical particles of metallic niobium powder containing a residual oxygen concentration of 0.673 mass% O were obtained. (C) 2013 Elsevier Ltd. All rights reserved.
• Fabrication of a meniscus microlens array made of anodic alumina by laser irradiation and electrochemical techniques

  Tatsuya Kikuchi, Yuhta Wachi, Taka-aki Takahashi, Masatoshi Sakairi, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 94 269 - 276 0013-4686 2013/04 [Refereed][Not invited]
   

  An anodic alumina microlens array was fabricated by laser irradiation and electrochemical techniques. An aluminum specimen covered with a porous oxide film was irradiated with a pulsed Nd-YAG laser, and then electropolished to dissolve the aluminum substrate. A well-defined semi-elliptical micropore was formed on the aluminum by electropolishing. The immersion of the electropolished specimen in a CrO3/H3PO4 solution resulted in the dissolution of the remaining anodic oxide film. Subsequent re-anodizing enabled the formation of a characteristic meniscus-shaped oxide film on the micropore. A microlens array made of the thin anodic alumina film, which showed flexibility and heat resistance, was successfully fabricated by the lift-off of the anodic oxide. (C) 2013 Elsevier Ltd. All rights reserved.
• Rapid fabrication of self-ordered porous alumina with 10-/sub-10-nm-scale nanostructures by selenic acid anodizing

  Osamu Nishinaga, Tatsuya Kikuchi, Shungo Natsui, Ryosuke O. Suzuki

  Scientific Reports Nature publishing group 3 2748  2045-2322 2013 [Refereed][Not invited]
   

  Anodic porous alumina has been widely investigated and used as a nanostructure template in various nanoapplications. The porous structure consists of numerous hexagonal cells perpendicular to the aluminum substrate and each cell has several tens or hundreds of nanoscale pores at its center. Because the nanomorphology of anodic porous alumina is limited by the electrolyte during anodizing, the discovery of additional electrolytes would expand the applicability of porous alumina. In this study, we report a new self-ordered nanoporous alumina formed by selenic acid (H2SeO4) anodizing. By optimizing the anodizing conditions, anodic alumina possessing 10-nm-scale pores was rapidly assembled (within 1 h) during selenic acid anodizing without any special electrochemical equipment. Novel sub-10-nm-scale spacing can also be achieved by selenic acid anodizing and metal sputter deposition. Our new nanoporous alumina can be used as a nanotemplate for various nanostructures in 10-/sub-10-nm-scale manufacturing.
• Growth Behavior of Anodic Porous Alumina Formed in Malic Acid Solution

  Tatsuya Kikuchi, Tsuyoshi Yamamoto, Ryosuke O. Suzuki

  Applied Surface Science Elsevier 284 907 - 913 0169-4332 2013 [Refereed][Not invited]
   

  The growth behavior of anodic porous alumina formed on aluminum by anodizing in malic acid solutions was investigated. High-purity aluminum plates were electropolished in CH3COOH/HClO4 solutions and then anodized in 0.5 M malic acid solutions at 293 K and constant cell voltages of 200–350 V. The anodic porous alumina grew on the aluminum substrate at voltages of 200–250 V, and a black, burned oxide film was formed at higher voltages. The nanopores of the anodic oxide were only formed at grain boundaries of the aluminum substrate during the initial stage of anodizing, and then the growth region extended to the entire aluminum surface as the anodizing time increased. The anodic porous alumina with several defects was formed by anodizing in malic acid solution at 250 V, and oxide cells were approximately 300–800 nm in diameter.
• Production of Nb-Ti-Ni alloy in molten CaCl2

  Ryunosuke Enmei, Tatsuya Kikuchi, Ryosuke O. Suzuki

  Electrochimica Acta 100 269 - 274 2013 [Refereed][Not invited]
  
• Calciothermic reduction of NiO by molten salt electrolysis of CaO in CaCl2 melt

  Reyna Famila Descallar-Arriesgado, Naoto Kobayashi, Tatsuya Kikuchi, Ryosuke O. Suzuki

  ELECTROCHIMICA ACTA 56 (24) 8422 - 8429 0013-4686 2011/10 [Refereed][Not invited]
   

  Metallic nickel powders with low and uniform residual oxygen content were produced from NiO using the molten salt electrolysis of CaO in CaCl2 melt. Suitable amount of CaO for the reduction was in the range of 0.5-3.0 mol% CaO. The electrical isolation of NiO from both electrodes could produce metallic Ni in CaCl2 melt. Separating the metal oxides from the cathode confirmed the mechanism of calciothermic reduction that the electrolysis of dissolved CaO in CaCl2 melt produces Ca, and that the dissolved Ca in molten CaCl2 successfully reduces NiO to metallic Ni. An average of about 600 ppm oxygen in Ni sample was achieved directly from oxide, when NiO was detached from the cathode. (C) 2011 Elsevier Ltd. All rights reserved.
• Corrosion resistant TiO2 film formed on magnesium by liquid phase deposition treatment

  R. Fujita, M. Sakairi, T. Kikuchi, S. Nagata

  ELECTROCHIMICA ACTA 56 (20) 7180 - 7188 0013-4686 2011/08 [Refereed][Not invited]
   

  Liquid phase deposition treatment (LPD) was applied to form a corrosion protective titanium dioxide (TiO2) film on commercially available pure magnesium. Changing the solution pH, from acidic to highly alkaline, and with the addition of sucrose, it becomes possible to form a highly adhesive and thin TiO2 film on commercially available pure magnesium without any heat treatment. The role of the sucrose may be attributed to the formation of tetrafluoroboric acid (BF4)(-) in the solution reducing the homogeneous nucleation of TiO2 in the LPD solution. The film formed in the weak alkaline environment shows better corrosion resistance than at other LPD conditions, while the average rest potential is the same as that of as-polished specimens. This low rest potential may be due to micro-cracks in the formed film and high activity of the magnesium substrate. (C) 2011 Elsevier Ltd. All rights reserved.
• アルミニウムおよびその酸化物からなる微細配線形成法の開発

  菊地竜也, 藤田哲, 坂入正敏

  表面技術 62 451 - 455 2011 [Not refereed][Invited]
  
• 溶液フロー型液滴セルによる樹枝上への局部銅めっきと金属構造体の作製

  坂入正敏, 後藤良仁, 菊地竜也, 伏見公志

  表面技術 62 511 - 515 2011 [Refereed][Not invited]
  
• Repassivation behavior of titanium in artificial saliva investigated with a photon rupture method

  Masatoshi Sakairi, Misaki Kinjyo, Tatsuya Kikuchi

  ELECTROCHIMICA ACTA 56 (4) 1786 - 1791 0013-4686 2011/01 [Refereed][Not invited]
   

  Repassivation kinetics of titanium were investigated in artificial saliva by the photon rupture method, PRM, combined with anodizing. PRM uses focused pulsed Nd-YAG laser beam irradiation to remove oxide film and metal. The effects of the applied potential and F(-) ions on the repassivation kinetics of titanium were examined electrochemically. All conditions in this study use specimens that were repassivated within about 100 ms after the laser beam irradiation. The current transients after the laser beam irradiation showed a rapid increase, followed by a decrease with a slope of the log i vs. log t plots of about -1.5. The measured slope is steeper than what would be expected with the high field oxide film formation theory. This result suggests that the oxidation of titanium takes place through a combination of electrochemical and chemical reactions. More NaF results in a higher peak current density and amount of charge after laser beam irradiation. The influence of F- ions on the repassivation kinetics may be explained by localized pH changes caused by dissolution of titanium immediately after the laser beam irradiation. (C) 2010 Elsevier Ltd. All rights reserved.
• Corrosion of Al-Sn-Bi alloys in alcohols at high temperatures. Part II: Effect of anodizing on corrosion

  Tatsuya Kikuchi, Yasuhito Hara, Masatoshi Sakairi, Tetsu Yonezawa, Akira Yamauchi, Hideaki Takahashi

  CORROSION SCIENCE 52 (8) 2525 - 2534 0010-938X 2010/08 [Refereed][Not invited]
   

  Nine kinds of Al alloys were anodized to form porous anodic oxide films, and then anodized specimens were immersed in 2-(2-(2-methoxyethoxy)ethoxy)ethanol (MEEE) and 2-(2-(2-butoxyethoxy)ethoxy)ethanol (BEEE) at 415 K. Al-1.0%Sn-1.0%Bi alloy was corroded severely in both BEEE and MEEE, whereas other eight alloys showed no corrosion. The corrosion proceeded under the anodic oxide films through cracks formed in the film. Cathodic polarization in Cu electroplating solution after corrosion suggested that the crack formation during immersion in hot MEEE is due to thermal expansion of the substrate and Sn and Bi containing particles included in the anodic oxide film. (C) 2010 Elsevier Ltd. All rights reserved.
• Corrosion of Al-Sn-Bi alloys in alcohol at high temperatures. Part I: Effects of the metallurgical structure of the alloys and the metal salt additions to alcohol

  Tatsuya Kikuchi, Yasuhito Hara, Masatoshi Sakairi, Tetsu Yonezawa, Akira Yamauchi, Hideaki Takahashi

  CORROSION SCIENCE 52 (4) 1482 - 1491 0010-938X 2010/04 [Refereed][Not invited]
   

  Corrosion of free machining Al alloys that contain Sn and Bi was investigated at 391-415 K in 2-(2-(2-methoxyethoxy)ethoxy)ethanol (MEEE) and 2-(2-(2-butoxyethoxy)ethoxy)ethanol (BEEE) with/without SnCl(2), Sn(OC(2)H(5))(4), FeCl(3), and CuCl(2). The Al-Sn-Bi alloy displayed severe pitting corrosion in MEEE similar to the Al-Sn alloy in BEEE at 415 K, and Sn and Sn/Bi were enriched on the surface of pits. Immersion tests of pure Al in MEEE containing Sn/Cu-salts at 415 K also showed severe corrosion and the deposition of metallic Sn and Cu on the surface. The corrosion mechanisms are discussed in terms of the electro-catalytic activity of the Sn enriched on the surface. (C) 2009 Elsevier Ltd. All rights reserved.
• The influence of initial surface conditions on field crystallization of anodic aluminum oxide films determined by synchrotron X-ray diffraction

  M. Sakairi, T. Kikuchi, T. Suda, D. Nagasawa, M. Sato

  SURFACE AND INTERFACE ANALYSIS 42 (4) 215 - 220 0142-2421 2010/04 [Refereed][Not invited]
   

  X-ray diffraction measurements were performed using synchrotron radiation at the SPring-8 facility and electrochemical techniques to investigate the effect of polishing methods and storage conditions on the crystal structure of air-formed oxide films and anodic oxide films formed on highly pure aluminum. Storage in an N(2) environment hinders local film breakdown during anodizing, and it was established that the X-ray diffraction measurements showed the presence of a gamma-Al(2)O(3) in the anodic oxide film formed on mechanically polished (MP) specimens. Formation of gamma-Al(2)O(3) during anodizing was inhibited by electropolishing because of the removal of the work-hardened layer that was formed on the MP by electro-polishing. The X-ray diffraction results do not show clear differences in the influence of the polishing method on the crystal structure of air formed oxide film. This is due to the very fast oxidation rate of the air-formed oxide film and very long storage times for the X-ray measurements. The anodic oxide film formed on aluminum, which has a very flat surface, shows color and the color depended on grain orientation. The electrochemical impedance of the MP specimen is slightly lower than that of the mechanically and then electrochemically polished specimen at the middle frequency range. This impedance difference may be due to formation of gamma-Al(2)O(3) in the amorphous anodic oxide film and the thickness of the film. Copyright (C) 2010 John Wiley & Sons, Ltd.
• Aluminum Microstructures on Anodic Alumina for Aluminum Wiring Boards

  Himendra Jha, Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi

  ACS APPLIED MATERIALS & INTERFACES 2 (3) 774 - 777 1944-8244 2010/03 [Refereed][Not invited]
   

  The paper demonstrates simple methods for the fabrication of aluminum microstructures on the anodic oxide him of aluminum. The aluminum sheets were first engraved (patterned) either by laser beam or by embossing to form deep grooves on the surface. One side of the sheet was then anodized, blocking the other side by using polymer mask to form the anodic alumina. Because of the lower thickness at the bottom part of the grooves, the part was completely anodized before the complete oxidation of the other parts. Such selectively complete anodizing resulted in the patterns of metallic aluminum on anodic alumina. Using the technique, we fabricated microstructures such as line patterns and a simple wiring circuit-board-like structure on the anodic alumina. The aluminum microstructures fabricated by the techniques were embedded in anodic alumina/aluminum sheet, and this technique is promising for applications in electronic packaging and devices.
• Fabrication of Cu Micro-rods with Co-axial Dual Capillary Solution Flow Type Droplet Cell and Electrodeposition with the Cell

  Masatoshi Sakairi, Yoshihito Goto, Koji Fushimi, Tatsuya Kikuchi, Hideaki Takahashi

  ELECTROCHEMISTRY 78 (2) 118 - 121 1344-3542 2010/02 [Refereed][Not invited]
   

  A new method for mask-less fabrication of metal micro-rods is described. The developed solution flow type droplet cell micro fabrication technique was applied to form Cu micro-rods. The use of an inner capillary tube as a mold during electrodeposition, makes it possible to form Cu micro-rods of about 15 mm length and about 100 mu m diameter. The length is controlled by the deposition time. From X-ray analysis and surface observations, the formed Cu micro-rod is polycrystalline and the crystals are very fine. The cross section of the micro-rod was almost circular and the diameter was almost the same throughout its length. This technique also makes it possible to form straight metal structures as well as branched and layered micro-rods. This layered micro-rod fabrication technique can be applied to form resistance controlled micro wires.
• Model Cut-edge Formed on Zinc Coated Steels by Laser Machining and Its Corrosion Behavior

  Masatoshi Sakairi, Akihiro Kageyama, Tatsuya Kikuchi

  Corrosion Science and Technology 9 29 - 33 2010 [Refereed][Not invited]
  
• Formation of Model Scratch on Pre-painted Coated Steel by Laser Machining and Its Wer/Dry Corrosion Behavior

  Masatoshi Sakairi, Miki Uchida, Tatsuya Kikuchi

  Zairyo-to-Kankyo Japan Society of Corrosion Engineering 59 (10) 379 - 381 0917-0480 2010 [Refereed][Not invited]
  
• Influence of Wettability on Corrosion Resistance of Anodized Aluminum in NaCl Solution

  Zheng Meng, Jha Himendra, Masatoshi Sakairi, Tatsuya Kikuchi

  Zairyo-to-Kankyo 腐食防食協会 59 (9) 335 - 337 0917-0480 2010 [Refereed][Not invited]
  
• Effect of cations on corrosion behavior of aluminum alloy in model tap water

  Kyohei Otani, Masatoshi Sakairi, Tatsuya Kikuchi, Akira Kaneko

  Zairyo to Kankyo/ Corrosion Engineering 59 (9) 330 - 331 0917-0480 2010 [Refereed][Not invited]
   

  The effect of cations on corrosion behavior of A3003-H24 in model tap water with immersion corrosion test and galvanic corrosion test was investigated. A3003-H24 (7 × 7 mm2) sheets were used as specimens. Doubly distilled water, 0.5 kmol m-3 H3BO3/0.05 kmol m-3Na2B4O7 with 1 mol m-3 NaCl, 1 mol m-3 KCl, and 0.5 mol m-3 NaCl/0.5 mol m-3 KCl solutions were used as model tap water. The galvanic current and specimen potential were measured for 86.4 ks at 298 K during galvanic corrosion tests. The results showed that the color of the specimens after immersion corrosion tests changes into light gray, and corrosion pits were also observed. The charge density in mixed cations added solution was lower than those of in single cation added solutions. The results suggested that coexistence of Na+ and K+ in dilute chloride ion solution acts as corrosion inhibitor.
• Development of a Low Solution Resistance Type Solution Flow Droplet Cell and Investigation of Its Electrochemical Performance

  Masatoshi Sakairi, Takuya Murata, Tatsuya Kikuchi, Koji Fushimi

  ISIJ INTERNATIONAL 50 (10) 1466 - 1470 0915-1559 2010 [Refereed][Not invited]
   

  A solution resistance reduced solution flow type micro-droplet cell with co-axial dual capillary tubes was developed. A Pt counter electrode wire, 50 mu m diameter, inserted in the inner capillary tube, successfully reduced solution resistance between the working and counter electrodes. The potentio-dynamic polarization measurements showed the electrochemical performance of developed droplet cell to be very similar to that of traditional macro sized electrochemical cells. The developed droplet cell was applied to obtain line profiles of a current at a constant potential across the surface of for cross-sections of model metal interfaces. The current changed at the model interface between deposited nickel and substrate, and the spatial resolution of the developed droplet cell was reduced with increasing scanning speed of the cell. The results reported in this paper suggest that this technique would be able to measure differences in corrosion resistance in welded metal components and base metals.
• Platinum Nanaflowers on Scratched Silicon by Galvanic Displacement for an Effective SALDI Substrate

  Hideya Kawasaki, Teruyuki Yao, Takashi Suganuma, Kouji Okumura, Yuichi Iwaki, Tetsu Yonezawa, Tatsuya Kikuchi, Ryuichi Arakawa

  CHEMISTRY-A EUROPEAN JOURNAL 16 (35) 10832 - 10843 0947-6539 2010 [Refereed][Not invited]
   

  We report a new and facile method for synthesizing 3D platinum nanoflowers (Pt Nfs) on a scratched silicon substrate by electroless galvanic displacement and discuss the applications of the Pt Nfs in surface-assisted laser desorption/ionization-mass spectrometry (SALDI-MS). Surface scratching of n-type silicon is essential to induce Pt Nf growth on a silicon substrate (to obtain a Pt Nf silicon hybrid plate) by the galvanic displacement reaction. The Pt Nf silicon hybrid plate showed excellent SALDI activity in terms of the efficient generation of protonated molecular ions in the absence of a citrate buffer. We propose that the acidity of the Si-OH moieties on silicon increases because of the electron-withdrawing nature of the Pt Nfs; hence, proton transfer from the Si OH groups to the analyte molecules is enhanced, and finally, thermal desorption of the analyte ions from the surface occurs. Signal enhancement was observed for protonated molecular ions produced from a titania nanotube array (TNA) substrate on which Pt nanoparticles had been photochemically deposited. Moreover, surface modification of the Pt Nf silicon hybrid plate by perfluorodecyltrichlorosilane (FDTS) (to obtain an FDTS-Pt Nf silicon hybrid plate) was found to facilitate soft SALDI of labile compounds. More interestingly, the FDTS-Pt Nf silicon hybrid plate acts 1) as a high-affinity substrate for phosphopeptides and 2) as a SALDI substrate. The feasibility of using the FDTS-Pt Nf silicon hybrid plate for SALDI-MS has been demonstrated by using a beta-casein digest and various analytes, including small molecules, peptides, phosphopeptides, phospholipids, carbohydrates, and synthetic polymers. The hybridization of Pt Nfs with a scratched silicon substrate has been found to be important for achieving excellent SALDI activity.
• Formation of artificial micro-pits on Al alloy with PRM and the localized corrosion behavior of the formed pits

  K. Yanada, M. Sakairi, T. Kikuchi, Y. Oya, Y. Kojima

  Surface and Interface Analysis 42 (4) 189 - 193 2010 [Refereed][Not invited]
  
• 導電性高分子を用いた再利用可能なアルミニウム製印刷板の試作

  菊地竜也, 島口寛子, 上田幹人, 坂入正敏, 米澤徹, 高橋英明

  表面技術 61 (9) 652 - 657 2010 [Refereed][Not invited]
  
• Growth of porous type anodic oxide films at micro-areas on aluminum exposed by laser irradiation

  Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi

  ELECTROCHIMICA ACTA 54 (27) 7018 - 7024 0013-4686 2009/11 [Refereed][Not invited]
   

  Aluminum covered with pore-sealed anodic oxide films was irradiated with a pulsed Nd-YAG laser to remove the oxide film at micro-areas. The specimen was re-anodized for long periods to examine the growth of porous anodic oxide films at the area where substrate had been exposed by measuring current variations and morphological changes in the oxide during the re-anodizing. The chemical dissolution resistance of the pore-sealed anodic oxide films in an oxalic acid solution was also examined by measuring time-variations in rest potentials during immersion. The resistance to chemical dissolution of the oxide film became higher with increasing pore-sealing time and showed higher values at lower solution temperatures. During potentiostatic re-anodizing at five 35-mu m wide and 4-mm long lines for 72 h after the film was removed the measured current was found to increase linearly with time. Semicircular columnar-shaped porous type anodic oxide was found to form during the re-anodizing at the laser-irradiated area, and was found to grow radially, thus resulting in an increase in the diameter. After long re-anodizing, the central and top parts of the oxide protruded along the longitudinal direction of the laser-irradiated area. The volume expansion during re-anodizing resulted in the formation of cracks, parallel to the lines, in the oxide film formed during the first anodizing. (C) 2009 Elsevier Ltd. All rights reserved.
• Palladium nanoparticle seeded electroless metallization of Al/Al2O3 surfaces

  Himendra Jha, Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi

  MATERIALS LETTERS 63 (16) 1451 - 1454 0167-577X 2009/06 [Refereed][Not invited]
   

  A simple method for the formation of palladium nanoparticles on aluminum and aluminum oxide surface is demonstrated. In the present method. the palladium nanoparticles obtained directly on the solid surface by immersing the specimen in palladium(II)acetate solution followed by reduction to metallic palladium by using sodium hypophosphite. In the investigation, as-received, boiled, electropolished and anodized aluminum was used as substrate. Additionally, the method is combined with the electroless nickel plating, which facilitates two steps metallization technique on the respective surfaces. In these cases, specimens were first immersed in palladium(II)acetate solution followed by immersion in electroless nickel plating solution, where, palladium reduced on the specimen surface providing catalytic site for the subsequent electroless nickel deposition. Using the technique. about 6 to 8.5 mu m thick Ni-P metallic layer was deposited on the specimen surface. (c) 2009 Elsevier B.V. All rights reserved.
• Micro- and Nano-Technologies Based on Anodizing of Aluminum – Combination of Laser Irradiation with Electrochemical Process

  Hideaki Takahashi, Masatoshi Sakairi, Tatsuya Kikuchi

  Electrochemistry 2009 [Not refereed][Invited]
  
• アノード酸化とマイクロ・テクノロジー

  高橋英明, 坂入正敏, 菊地竜也, Jha Himendra

  表面技術 60 143 - 150 2009 [Not refereed][Invited]
  
• 溶液フロー型液滴セルを用いる局部電気化学

  坂入正敏, 村田拓哉, 菊地竜也, 伏見公志

  防錆管理 53 361 - 366 2009 [Not refereed][Invited]
  
• Metallization of Oxide / Hydroxide Film of Aluminum: the Palladium Activation Techniques

  Himendra Jha, Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi

  Journal of the Surface Finishing Society of Japan 60 (3) 208 - 212 2009 [Refereed][Not invited]
  
• 低密度球の水浴中への侵入特性に及ぼす表面粗さの影響

  田中正幸, 菊地竜也, 辻野良二, 井口学

  実験力学 日本実験力学会 9 (2) 140 - 146 1346-4930 2009 [Refereed][Not invited]
   

  High quality steel has recently been required in many industrial fields. One of the typical impurities contained in molten iron is sulfur. Some desulphurization processes have been developed to decrease its content down to very low level. Desulfurization chemicals such as CaO powder are introduced into a molten iron bath by mechanical agitation or by powder injection with carrier gas. In this research attention is paid on the powder injection. The chemicals are commonly poorly wetted by molten iron, and accordingly, the carrier gas attaches to the surface of each particle in the course of penetrating into the bath. The buoyancy force acting on the particle reduces the penetration distance in the bath and lowers the efficiency of the process significantly. Model experiments are carried out on the influence of the surface roughness of a sphere on the penetrating behavior of the sphere in a molten iron bath, because the surface of the desulfurization chemical particles is usually rough. The roughness is measured with a laser microscope.
• ポリピロール／金の２層構造を有する３次元マイクロアクチュエーターの作製

  菊地竜也, 上田晋吾, 上田幹人, 坂入正敏, 高橋英明

  表面技術 60 (5) 335 - 341 2009 [Refereed][Not invited]
  
• Effect of potential, temperature, and fluoride ions on the repassivation kinetics of titanium in PBS with the photon rupture method

  Masatoshi Sakairi, Hiroomi Miyata, Tatsuya Kikuchi, Hideaki Takahashi

  Laser Chemistry 2009 436065  2009 [Refereed][Not invited]
  
• Development of a novel microstructure fabrication method with co-axial dual capillary solution flow type droplet cells and electrochemical deposition

  Masatoshi Sakairi, Fumihito Sato, Yoshihito Gotou, Koji Fushimi, Tatsuya Kikuchi, Hideaki Takahashi

  ELECTROCHIMICA ACTA 54 (2) 616 - 622 0013-4686 2008/12 [Refereed][Not invited]
   

  A new method for maskless fabrication of metallic patterns or structures on metals is described. A solution flow type droplet cell, with co-axial dual capillaries was applied to form fine metal structures such as strips and rods. This type of droplet cell enables movement of the cell during formation. Nickel fine patterns with a width of about 200 mu m were formed on a Cu substrate. The width of the formed pattern does not change with the scanning speed of the cell, but the thickness of the formed pattern changes with the speed. Two different deposition modes were examined to form metal rods, one is a mold free deposition mode and the other is a mold assisted deposition mode. Both modes enable the formation of Ni rods. however, reproducibility of mold free deposition mode was not good. The mold assisted deposition mode has far better the reproducibility, because of the use of the inside wall of the 100 mu m diameter inner tube as the mold. It is possible to form nickel micro-rods, about 100 mu m in diameter and 12 mm long with relatively smooth surfaces by the mold assisted deposition mode. (c) 2008 Elsevier Ltd. All rights reserved.
• Fabrication of micro-dot arrays and micro-walls of acrylic acid/melamine resin on aluminum by AFM probe processing and electrophoretic coating

  S. Kurokawa, T. Kikuchi, M. Sakairi, H. Takahashi

  ELECTROCHIMICA ACTA 53 (28) 8118 - 8127 0013-4686 2008/11 [Refereed][Not invited]
   

  Micro-dot arrays and micro-walls of acrylic acid/melamine resin were fabricated on aluminum by anodizing, atomic force microscope (AFM) probe processing, and electrophoretic deposition. Barrier type anodic oxide films of 15 rim thickness were formed on aluminum and then the specimen was scratched with an AFM probe in a solution containing acrylic acid/melamine resin nano-particles to remove the anodic oxide film locally. After scratching, the specimen was anodically polarized to deposit acrylic acid/melamine resin electrophoretically at the film-removed area. The resin deposited on the specimen was finally cured by heating. It was found that scratching with the AFM probe on open circuit leads to the contamination of the probe with resin, due to positive shifts in the potential during scratching. Scratching of the specimen under potentiostatic conditions at -1.0 V, however, resulted in successful resin deposition at the film-removed area without probe contamination. The rate of resin deposition increased as the specimen potential becomes more positive during electrophoretic deposition. Arrays of resin dots with a few to several tens mu m diameter and 100-1000 nm height, and resin walls with 100-1000 nm height and 1 mu m width were obtained on specimens by successive anodizing, probe processing. and electrophoretic deposition. (C) 2008 Elsevier Ltd. All rights reserved.
• カソード分極中におけるアノード酸化皮膜化成ニオブ電極への水素吸収

  長原和弘, 菊地竜也, 伏見公志, 坂入正敏, 高橋英明, 泉知夫

  表面技術 59 (5) 326 - 332 2008 [Refereed][Not invited]
  
• Synthesis of aluminum oxy-hydroxide nanofibers from porous anodic alumina

  Himendra Jha, Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi

  echnology 395603(6pp)  2008 [Refereed][Not invited]
  
• 陽極酸化したアルミニウムの異種金属接触腐食 —酸化物皮膜構造と塩化物イオン濃度の影響—

  坂入正敏, 下山由起也, 長澤大介, 菊地竜也, 高橋英明

  Zairyo-to-Kankyo Japan Society of Corrosion Engineering 57 (4) 194 - 200 0917-0480 2008 [Refereed][Not invited]
   

  The effect of anodic oxide film structure, barrier type and porous type on galvanic corrosion resistance of aluminum in 0.5 kmol/m³ H₃BO₃ / 0.05 kmol/m³ Na₂B₄O₇ with NaCl was examined by electrochemical random signal (electrochemical noise) analysis technique. When pitting corrosion occurs, rest potential suddenly decreases and current increases rapidly, and rest potential and current change with fluctuation during galvanic corrosion. The galvanic current change correlates closely with corrosion potential change. As the thickness of both types of anodic oxide films and decreasing of chloride ion concentration, the incubation time of pitting corrosion became longer, and incubation time of pitting corrosion of specimen formed porous type anodic oxide film is longer than that of specimen formed barrier type anodic oxide film. The inverse of incubation time increase with chloride ion concentration to the power of n, [Cl^–]ⁿ. The value of n is between 1.2 and 2.5 in both oxide films.
• 無電解めっきと電気めっきによるセラミックス上への厚膜白金析出

  菊地竜也, 渡辺健, 坂入正敏, 高橋英明, 丸子智弘

  表面技術 59 51 - 56 2008 [Refereed][Not invited]
  
• 無電解めっきとレーザー照射による有機樹脂基板上へのCuマイクロパターン形成

  菊地竜也, 和智悠太, 坂入正敏, 高橋英明, 飯野潔, 片山直樹

  表面技術 59 (8) 555 - 561 2008 [Not refereed][Not invited]
  
• Influence of zinc ions on initial stage of localized corrosion of Zn and Zn-Al alloy coated steels with photon rupture method

  Masatoshi Sakairi, Yoshiyuki Uchida, Tatsuya Kikuchi, Hideaki Takahashi

  ISIJ INTERNATIONAL 48 (7) 988 - 993 0915-1559 2008 [Refereed][Not invited]
   

  The effect of pre-dissolved Zn ions in the solutions on the initial stage of localized corrosion after oxide films of Zn and Zn-Al alloy coated steels were removed by a photon rupture method, focused pulsed Nd-YAG laser beam irradiation, was investigated electrochemically. Zn ions can be inhibited dissolution of the Zn coated layer by precipitation of zinc hydroxide, which is formed by hydrolysis reaction of dissolved Zn ions in neutral buffer solutions. However, Zn ions do not affect the dissolution of a Zn-Al alloy coated layer. The absence of inhibition of the Zn-Al layer dissolution can be explained by pH change to lower values at the irradiated area by the hydrolysis reaction of the dissolved Al ions. The effect of Zn ions on corrosion inhibition of the coated layer by the photon rupture method established here was in good agreement with polarization experiments.
• Dielectric properties of Al-Si composite oxide films formed on electropolished and DC-etched aluminum by electrophoretic sol-gel coating and anodizing

  M. Sunada, H. Takahashi, T. Kikuchi, M. Sakairi, S. Hirai

  JOURNAL OF SOLID STATE ELECTROCHEMISTRY 11 (10) 1375 - 1384 1432-8488 2007/10 [Refereed][Not invited]
   

  Highly pure aluminum specimens (99.99%) after electropolishing and DC-etching were covered with SiO2 films by electrophoretic sol-gel coating and were anodized in neutral boric acid/borate solutions. Time-variations in cell voltage during electrophoretic sol-gel coating and in anode potential during anodizing were monitored. Structure and dielectric properties of the anodic oxide films were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and electrochemical impedance spectroscopy (EIS). It was found that electrophoretic sol-gel coating forms uniform SiO2 films on the surface of both electropolished and DC-etched specimens. Anodizing of specimens after electrophoretic coating lead to the formation of anodic oxide films consisting of two layers: an inner alumina layer and an outer Al-Si composite oxide layer. The anodic oxide films formed, thus, had slightly higher capacitances than those formed on aluminum without any coating. Higher heating temperatures after electrophoretic deposition caused the increase in capacitance of anodic oxide films more effectively. Anodizing in a boric acid solution after SiO2 coating on DC-etched foil allowed the anode potential to reach a value higher than 1,000 V, resulting in 39% higher capacitances than those on specimens without SiO2 film.
• Microfabrication of an anodic oxide film by anodizing laser-textured aluminium

  Himendra Jha, Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi

  JOURNAL OF MICROMECHANICS AND MICROENGINEERING 17 (10) 1949 - 1955 0960-1317 2007/10 [Refereed][Not invited]
   

  A simple method for the fabrication of microstructures of an aluminium anodic oxide film ( anodic alumina) by anodizing laser-textured aluminium is demonstrated. In the process, the aluminium substrate was first textured by a low power laser beam, and then the textured aluminium was subjected to anodizing, to develop a continuous, thick porous layer on the textured surface. Microstructures with a depth of a few to several tens of micrometres were fabricated successfully on the anodic oxide film by using various combinations of laser power density and laser scanning speed. Removing the film from the aluminium substrate enables the fabrication of various 2D and 3D microstructures from anodic alumina.
• Laser micromachining of porous anodic alumina film

  H. Jha, T. Kikuchi, M. Sakairi, H. Takahashi

  APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 88 (4) 617 - 622 0947-8396 2007/09 [Refereed][Not invited]
   

  A laser direct-write process on porous anodic alumina film is carried out for the fabrication of microstructure on the film, using nanosecond, second harmonic Nd:YAG laser. Laser micromachining can be preformed in two different ways on colored and pore-sealed anodic alumina film, to generate microstructures on the film. Removal of the aluminum substrate before laser irradiation greatly improves the shape characteristics of the microstructure. The depth of microstructures can be controlled by the power and the scanning speed of the laser beam. Several structures with depths from 1 to 35 mu m were fabricated on anodic alumina film with good precision and reproducibility.
• Nb2O5 deposition on aluminum from NbCl5-used sol and anodizing of Nb2O5-coated Al

  Shun Koyama, Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi, Shinji Nagata

  ELECTROCHEMISTRY 75 (8) 573 - 575 1344-3542 2007/08 [Refereed][Not invited]
   

  Formation of Nb2O5 films on aluminum was attempted by sol-gel coating, using NbCl5 as a precursor. The structure and the dielectric properties of anodic oxide films formed on aluminum by sol-gel coating and the subsequent anodizing were examined. Anodic oxide film formed by this process was composed of an inner Al2O3 layer and an outer Nb2O5 layer. The capacitance of the anodic oxide films formed on Nb2O5-coated specimens was at most 34 % higher than that of anodic oxide films on aluminum without coating.
• Area-selective microscale metallization on porous anodic oxide film of aluminium

  Himendra Jha, Tatsuya Kikuchi, Masatoshi Sakairi, Hideaki Takahashi

  ELECTROCHEMISTRY COMMUNICATIONS 9 (7) 1596 - 1601 1388-2481 2007/07 [Refereed][Not invited]
   

  A new method for micropatterning of metallic patterns on porous anodic oxide film of aluminium is described. The porous anodic oxide film was impregnated with organic dye and palladium ions before the hydrothermal pore-sealing. The surface layers formed during the pore-sealing, i.e. outer acicular hydroxide layer and a compact intermediate sub-layer trap the palladium ion underneath the layers. Exposing the palladium enriched area by the help of laser beam followed by electroless nickel deposition results the deposition of nickel on the laser-exposed part. Thickness of the deposits can be up to about 2-3 mu m, after about the 20 min of immersion in electroless nickel plating bath. The metallic micropatterns, formed by the method are crack free, smooth and uniform over extended length. (C) 2007 Elsevier B.V. All rights reserved.
• Development of three-electrode type micro-electrochemical reactor on anodized aluminum with photon rupture and electrochemistry

  Masatoshi Sakairi, Masashi Yamada, Tastuya Kikuchi, Hideaki Takahashi

  ELECTROCHIMICA ACTA 52 (21) 6268 - 6274 0013-4686 2007/06 [Refereed][Not invited]
   

  Photon rupture with a focused single pulse of pulsed YAG-laser irradiation was used to fabricate an aluminum electrochemical micro-reactor. Porous type anodic oxide film formed on aluminum specimens was irradiated in solutions with a pulsed Nd-YAG laser beam through a convex lens to fabricate micro-channels, micro-electrode, and through holes (for reference electrode, solution inlet, and outlet). During irradiation, specimens were moved by a computer controlled XYZ stage. After irradiation, the surface of the micro-channel and through hole were again treated to form anodic oxide film and the surface of the micro-electrode was treated electrochemically to provide an An layer. The calculated volume of the micro-reactor including micro-channel and through holes is about 1.5 mu l. The cyclic voltammogram of the micro-electrochemical cell was measured in K3Fe(CN)(6)/K4Fe(CN)(6) with both static and flowing solution at different scanning rates. The anodic and cathodic peak currents were measured and the values depended on scanning rate and ion concentration when the solution was static. With the flowing solution, limiting currents were observed and the anodic limiting current was increased with the cubic root of the solution flow rate. (c) 2007 Elsevier Ltd. All rights reserved.
• Micro-patterning in anodic oxide film on aluminium by laser irradiation

  H. Jha, T. Kikuchi, M. Sakairi, H. Takahashi

  ELECTROCHIMICA ACTA 52 (14) 4724 - 4733 0013-4686 2007/04 [Refereed][Not invited]
   

  Microstructures such as microchannels and microchambers were fabricated on anodic oxide film of aluminium with laser direct patterning technique. The aluminium substrate covered with porous type anodic oxide film was dyed with organic dyes followed by hydrothermal treatment. The coloured and pore sealed film shows much higher absorption then as-formed porous film, that makes possible to pattern various types of microstructures on the film by removing the upper part of the film surface by laser irradiation. Structure of the crystallized hydroxide layer on the surface of the anodic oxide film, formed during pore sealing, as well as the partial removal of anodic oxide film from the surface is described. Microstructures with depth lower than 1-27 mu m were patterned successfully on 16 and 32 mu m thick anodic oxide film surfaces, using various combinations of laser power and laser scanning speed. The affect of the laser scanning speed and laser power density on the shape of the microstructures is also explained. (c) 2007 Elsevier Ltd. All rights reserved.
• Fabrication of a three-dimensional micro-manipulator by laser irradiation and electrochemical techniques and the effect of electrolytes on its performance

  T. Kikuchi, Y. Akiyama, A. Ueda, A. Sakairi, H. Takahashi

  ELECTROCHIMICA ACTA 52 (13) 4480 - 4486 0013-4686 2007/03 [Refereed][Not invited]
   

  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.
• Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

  T. Kikuchi, H. Takahashi, T. Maruko

  ELECTROCHIMICA ACTA 52 (7) 2352 - 2358 0013-4686 2007/02 [Refereed][Not invited]
   

  Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZ theta stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 mu m line width were obtained successfully. (c) 2006 Elsevier Ltd. All rights reserved.
• Local deposition of polypyrrole on aluminum by anodizing, laser irradiation, and electrolytic polymerization and its application to the fabrication of micro-actuators

  Y Akiyama, T Kikuchi, M Ueda, M Iida, M Sakairi, H Takahashi

  ELECTROCHIMICA ACTA 51 (23) 4834 - 4840 0013-4686 2006/06 [Refereed][Not invited]
   

  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.
• アノード酸化を利用するマイクロ・ナノテクノロジー

  菊地竜也, 秋山好之, 黒川真也, 長原和宏, 坂入正敏, 高橋英明

  日本材料科学会誌 43 136 - 141 2006 [Not refereed][Invited]
  
• Formation of Al-Si Composite Oxide Films on Aluminum by Electrophoretic Sol-Gel Coating/Anodizing

  H.Takahashi, M.Sunada, T.Kikuchi, M.Sakairi, S.Hirai

  Passivation of Materials and Semiconductors, and Thin Oxide Layers, 685 - 690 2006 [Refereed][Not invited]
  
• レーザー照射と電解エッチングを用いたアルミニウムの表面微細加工

  菊地竜也, 高橋英明, 丸子智弘

  表面技術 56 (7) 409 - 414 2005 [Refereed][Not invited]
  
• Fabrication of Micro-Circuit Board by Aluminum Anodizing and Laser Irradiation-Effect of Laser Irradiation Condition on Micro-Pattern Formation-:−Effect of Laser Irradiation Condition on Micro-Pattern Formation−

  KIKUCHI Tatsuya, TAKAHASHI Hideaki

  Jitsumu Hyomen Gijutsu The Surface Finishing Society of Japan 56 (9) 528 - 534 0915-1869 2005 [Refereed][Not invited]
   

  A prototype circuit board with micro-metal patterns was fabricated by laser irradiation and an electrochemical technique. An aluminum specimen covered with porous type oxide films was irradiated with a pulsed laser beam, using a convex lens with a focal length of 10mm. The oxide film was removed in an irregularly shaped area, using a 1.5mm diameter laser beam, while the oxide film was removed in a circle with 5μm diameter, using a 1.0mm diameter laser beam, due to an aberration of the convex lens. The diameter of the film-removed area decreased with decreasing laser power and laser irradiation time. Laser irradiation with a beam expander and a doublet lens caused the removal of the oxide film in a circle with 3μm diameter. Fine metal patterns with 4μm line width was fabricated on the epoxy resin board by successive steps of aluminum anodizing, laser irradiation, electroplating, resin attaching, and removal of the aluminum substrate and oxide film.
  
• Fabrication of nickel micro-pattern on insulating board by anodizing/laser irradiation/electrodeposition

  T Kikuchi, M Sakairi, H Takahashi, Y Abe, N Katayama

  SURFACE & COATINGS TECHNOLOGY 169 199 - 202 0257-8972 2003/06 [Refereed][Not invited]
   

  Nickel micro-pattern was fabricated on an insulating board via anodizing aluminum, laser irradiation, nickel electroplating, insulating board attachment and aluminum substrate dissolution. Aluminum specimens covered with porous type oxide films were irradiated with a pulsed Nd-yttrium aluminum garnet laser through a convex lens with 10 mm focal length in a nickel electroplating solution to remove the anodic oxide film. The oxide film was destructed with minimum 6 mum width at the focal position. After laser irradiation, a nickel metal layer was electrodepo sited at only the laser irradiated area. The specimen was attached on an epoxy resin before dissolving aluminum substrate. A nickel micro-pattern with a 9 mum line width and 12 mum intervals was obtained on the insulating board. (C) 2003 Elsevier Science B.V All rights reserved.
• アノード酸化を基礎とするアルミニウム表面技術における最近の話題

  高橋英明, 坂入正敏, 渡辺恵司, 菊地竜也, 山田雅史

  奥野トップテクノフォーカス 28 1 - 12 2003 [Not refereed][Invited]
  
• バルブ金属アノード酸化皮膜の微細構造とマイクロ・ナノテクノロジーへの応用

  高橋英明, 坂入正敏, 菊地竜也, 山田雅史

  表面技術 54 436 - 441 2003 [Not refereed][Invited]
  
• Three-dimensional Microstructure Fabrication with Aluminum Anodizing, Laser Irradiation, and Electrodeposition

  T. Kikuchi, M. Sakairi, H. Takahashi

  Journal of the Electrochemical Society 150 (9) C567 - C572 2003 [Refereed][Not invited]
  
• アルミニウムのアノード酸化とレーザー照射を用いた微細プリント配線板の作製 –パターン形成における酸化皮膜の厚さの影響-

  菊地竜也, 坂入正敏, 高橋英明, 阿部芳彦, 片山直樹

  表面技術 54 (2) 137 - 144 2003 [Refereed][Not invited]
  
• Local surface modification of aluminum by laser irradiation

  T Kikuchi, SZ Chu, S Jonishi, M Sakairi, H Takahashi

  ELECTROCHIMICA ACTA 47 (1-2) 225 - 234 0013-4686 2001/09 [Refereed][Not invited]
   

  A novel method involving a combination of pulsed YAG laser irradiation and electrochemistry for chemical and physical modification of aluminum surface at a selected area is reviewed. Local metal deposition is carried out by successive steps of anodizing, laser irradiation, and electroplating (or electroless plating), and the fabrication of a prototype for printed circuit boards is attempted. Local organic film deposition with anodizing, laser irradiation, and electrophoretic deposition is introduced, and the formation of microtrenches and pores on aluminum surfaces with anodizing, laser irradiation, and electrochemical etching (or chemical etching) is also described. It is emphasized that the key technology in these procedures is to use aluminum as a target for the laser irradiation in solution, and that anodic oxide films on aluminum play an important role in the processes. (C) 2001 Elsevier Science Ltd. All rights reserved.
• アルミニウムのアノード酸化を利用したプリント配線板の作製

  高橋英明, 坂入正敏, 菊地竜也

  表面科学 22 370 - 375 2001 [Not refereed][Invited]
  
• Fabrication of Micropores and Grooves on Aluminum by Laser Irradiation and Electrochemical Technique

  T. Kikuchi, M. Sakairi, H. Takahashi, Y. Abe, N. Katayama

  Journal of the Electrochemical Society 148 (11) C740 - C745 2001 [Refereed][Not invited]
  
• Alアノード酸化とレーザー照射を利用した金属微細構造の作製 –新LIGAプロセスを目指して-

  菊地竜也, 諸松竹, 加藤善大, 坂入正敏, 高橋英明

  表面技術 50 697 - 704 1999 [Not refereed][Invited]
  
• アノード酸化を基礎とする新規なアルミニウム表面改質・加工技術 –機能性表面の創成を目指して-

  高橋英明, 坂入正敏, 諸松竹, 渡辺恵司, 菊地竜也, 三輪浩二, 加藤善大, 上西早苗

  軽金属 50 544 - 551 1999 [Not refereed][Invited]
  
• アルミニウムのアノード酸化／レーザー照射／電気めっきを用いた微細回路板の作製

  菊地竜也, 坂入正敏, 高橋英明, 阿部芳彦, 片山直樹

  表面技術 50 (9) 829 - 835 1999 [Refereed][Not invited]
  

Books etc

• 超撥水・超撥油・滑液性表面の技術（第２巻）

  菊地竜也, 小野田文哉, 近藤龍之介, 中島大希, 鈴木亮輔, 夏井俊悟 (Contributor陽極酸化による滑落性制御型超撥水・超撥油アルミニウム表面の創製)
  サイエンス＆テクノロジー 2021/03
• 撥水・撥油・親水性材料の開発動向

  菊地竜也, 中島大希, 近藤龍之介, 鈴木亮輔, 夏井俊悟 (Contributor陽極酸化によるアルミニウム表面のナノ構造制御と超親水性・超撥水性の発現)
  シーエムシー出版 2021/03
• 脱石油に向けたCO2資源化技術 ―化学・生物プロセスを中心にー

  鈴木亮輔, 坂口紀史, 菊地竜也, 夏井俊悟 (ContributorCO2還元によるカーボンナノチューブの生成)
  シーエムシー出版 2020/07
• Extractive Metallurgy of Titanium

  Ryosuke O. Suzuki, Shungo Natsui, Tatsuya Kikuchi (ContributorOS process: calciothermic reduction of TiO2 via CaO electrolysis in molten CaCl2)
  Elsevier 2019 287-314
• ナノファイバーの製造・加工技術とその応用事例

  菊地竜也, 中島大希 (Contributorアノード酸化によるアルミナナノファイバーの作製)
  技術情報協会 2019
• 超親水・親油性表面の技術

  菊地竜也, 中島大希 (Contributorアノード酸化アルミナナノファイバーによるアルミニウム表面の高速超親水化技術)
  サイエンス＆テクノロジー 2018
• キャパシタ便覧

  高橋英明, 坂入正敏, 菊地竜也, 小山瞬 (Joint work複合酸化物皮膜の形成によるアルミニウム電解コンデンサーの大容量化)
  丸善 2009
• Progress in Corrosion Science and Engineering, Modern Aspects of Electrochemistry

  Hideaki Takahashi, Masatoshi Sakairi, Tatsuya Kikuchi (Joint workAnodic Oxide Films on Aluminum: Their Significance for Corrosion Protection and Micro- and Nano-Technologies-)
  Springer 2009

Conference Activities & Talks

• アルミニウムの陽極酸化によるナノ構造構築と機能の発現  [Invited]

  菊地竜也

  表面技術協会第149回講演大会  2024/03
• 加熱クラック生成挙動に及ぼすアルマイトのナノ構造の影響  [Invited]

  中島大希, 布村順司, 菊地竜也

  SURTECH2024 表面技術協会ARS第113回例会  2024/01
• アルミニウムの陽極酸化によるナノ構造構築と機能の発現  [Invited]

  菊地竜也

  表面技術協会冬季セミナー「研究/技術者のための表面処理基礎講座」  2023/12
• Fabrication of slippery and sticky superhydrophobic aluminum via anodizing in pyrophosphoric acid  [Invited]

  Tatsuya Kikuchi, Fumiya Onoda, Junnosuke Yasuda, Mana Iwai

  International Conference on Surface Engineering (ISCE2023) & Regional INTERFINISH 2023  2023/11
• 塩基性電解質を用いたアルミニウムのアノード酸化  [Invited]

  岩井愛, 菊地竜也

  表面技術協会ARS第38回姫路コンファレンス  2023/11
• ハニカムナノ構造をもつ酸化アルミニウム皮膜の作製と三次元複雑構造への応用展開  [Invited]

  岩井愛, 菊地竜也

  第9回北大・部局横断シンポジウム  2023/10
• アルミニウムのアノード酸化の基礎2  [Invited]

  菊地竜也

  表面技術協会ARS第112回例会  2023/09
• アルミニウムのアノード酸化の基礎1  [Invited]

  菊地竜也

  表面技術協会ARS第112回例会  2023/09
• 新規な電解質を用いたアルミニウムのアノード酸化によるナノテクノロジー  [Invited]

  菊地竜也

  電気化学会第90回大会  2023/03
• 塩化ナトリウム／エチレングリコール溶液を用いたポーラスアルミナの高速電解剥離  [Invited]

  菊地竜也, 宮本和哉, 岩井愛

  表面技術協会ARS第37回三河コンファレンス  2022/11
• アルミニウムのアノード酸化の基礎2  [Invited]

  菊地竜也

  表面技術協会ARS第109回例会  2022/09
• アルミニウムのアノード酸化の基礎1  [Invited]

  菊地竜也

  表面技術協会ARS第109回例会  2022/09
• アルミニウムの陽極酸化による自己規則化ナノ構造の作製と応用  [Invited]

  菊地竜也

  電気化学会電解科学技術委員会第116回委員会  2022/06
• 新規な電解質を用いた陽極酸化によるポーラスアルミナのナノ構造制御  [Invited]

  菊地竜也, 岩井愛

  日本金属学会2022年春期第170回講演大会  2022/03
• アルミニウムのアノード酸化の基礎２  [Invited]

  菊地竜也

  表面技術協会ARS第107回例会  2021/12
• アルミニウムのアノード酸化の基礎１  [Invited]

  菊地竜也

  表面技術協会ARS第107回例会  2021/12
• Fabrication of self-ordered porous alumina by anodizing aluminum in alkaline sodium tetraborate solution  [Invited]

  Mana Iwai, Tatsuya Kikuchi

  Hokkaido University-Seoul National University The 10th Joint Symposium on Materials Science and Engineering  2021/12
• Fabrication of sticky and slippery superhydrophobic aluminum surfaces by electrochemical anodizing  [Invited]

  Tatsuya Kikuchi, Fumiya Onoda, Ryunosuke Kondo, Daiki Nakajima

  Hokkaido University-Seoul National University The 10th Joint Symposium on Materials Science and Engineering  2021/12
• アノード酸化入門  [Invited]

  菊地竜也

  表面技術協会2020年夏季セミナー「表面処理入門講座」  2020/08
• 海外におけるアノード酸化研究の潮流とナノ構造体作製技術  [Invited]

  菊地竜也

  表面技術協会ARS第36回富山コンファレンス  2019/10
• Fabrication of Self-Ordered Porous alumina by Etidronic Acid Anodizing  [Invited]

  Tatsuya Kikuchi, Mana Iwai, Yusuke Suzuki, Shungo Natsui, Ryosuke O. Suzuki

  3rd International Symposium on Anodizing Science and Technology (AST2019)  2019/06
• アルミニウムのアノード酸化の基礎  [Invited]

  菊地竜也

  表面技術協会ARS第102回例会 ーチュートリアル：アノード酸化の基礎ー  2019/05
• ピロリン酸アノード酸化による高速超親水・滑落性制御型超撥水アルミニウム材料の創製  [Invited]

  菊地竜也, 中島大希, 夏井俊悟, 鈴木亮輔

  表面技術協会第139回講演大会  2019/03
• アルミニウムアノード酸化皮膜の基礎  [Invited]

  菊地竜也

  表面技術協会ARS第99回例会 ー平成30年度チュートリアル：アノード酸化の基礎ー  2018/06
• エチドロン酸アノード酸化による高電圧・硬質・発光皮膜の作製  [Invited]

  菊地竜也

  表面技術協会ARS第34回松島コンファレンス  2017/10
• 新規な電解質を用いた多孔質皮膜の生成挙動と特性  [Invited]

  菊地竜也

  表面技術協会ARS第97回例会  2017/09
• 新規な電解質を用いたアノード酸化によるアルミニウム表面の機能化  [Invited]

  菊地竜也

  表面技術協会ARS第33回熱海コンファレンス  2016/10
• アルミニウムのアノード酸化と機能化  [Invited]

  菊地竜也

  軽金属学会 新エネルギー向け表面処理研究部会 講演会  2015/10
• ポーラスアルミナの生成挙動におよぼす電解質化学種の影響  [Invited]

  菊地竜也

  表面技術協会ARS第31回足柄コンファレンス  2014/11
• カルシウム還元を用いた電解コンデンサ用マイクロポーラス合金の作製  [Invited]

  菊地竜也, 吉田雅純, 夏井俊悟, 幅崎浩樹, 鈴木亮輔

  2014年電気化学秋季大会  2014/09
• 新しいナノポーラスアルミナを求めて  [Invited]

  菊地竜也

  第30回ARS弘前コンファレンス  2013/11
• ポーラス型アノード酸化皮膜のマイクロ・ナノテクノロジー  [Invited]

  菊地竜也

  資源・素材2013 平成25年度資源・素材関係学協会合同秋季大会  2013/09
• カルシウム無電解還元法によるコンデンサ用Ti合金微粒子の作製  [Invited]

  菊地竜也, 吉田雅純, 鈴木亮輔

  第29回ARS伊豆長岡コンファレンス  2012/11
• レーザー照射と電気化学的手法を融合した新規な微細構造体の創製  [Invited]

  菊地 竜也

  2010年北海道夏期セミナー  2010/07
• 高温アルコール中におけるアルミニウム合金の腐食 —腐食挙動におよぼす合金組成、溶液組成およびアノード酸化皮膜の影響—  [Invited]

  菊地 竜也

  表面技術協会第119回講演大会  2009/03
• レーザー微細加工と貴金属めっき —異なる２つの表面技術—  [Invited]

  菊地 竜也

  表面技術協会北海道支部特別講演会  2006/12
• アルミニウムのマイクロパターニング  [Invited]

  菊地 竜也

  表面技術協会ARS第23回有明コンファレンス  2006/11
• レーザー微細加工法と電気化学による貴金属三次元構造体の作製  [Invited]

  菊地 竜也

  第22回ライラックセミナー・第11回若手研究者交流会  2005/06
• アノード酸化皮膜のレーザー加工を用いた三次元微細構造体作製法の開発  [Invited]

  菊地 竜也

  第６回２１世紀の境界領域研究を考えるシンポジウム  2004/06

MISC

• 北海道大学大学院工学研究院材料科学部門エコプロセス工学研究室 研究室紹介

  菊地竜也  アルミプロダクツ  36-  (2)  14  -15  2023  [Not refereed][Invited]
  
• 会員提案シンポジウム「材料電気化学」のご案内 テーマ材料電気化学が拓く金属・半導体の技術革新

  菊地竜也  電気化学  90-  286  2022  [Not refereed][Invited]
  
• アノード酸化の未来を創る

  菊地竜也  軽金属  71-  323  -324  2021  [Not refereed][Invited]
  
• 研究者紹介 一風変わったアノード酸化

  菊地竜也  表面技術  71-  355  2020  [Not refereed][Invited]
  
• AST2014国際会議報告 –さらに新しいアノード酸化の世界-

  菊地竜也  表面技術  66-  209  -211  2015  [Not refereed][Invited]
  
• 2014年電気化学会秋季大会報告

  大谷文章, 菊地竜也  Electrochemistry  83-  122  -125  2015  [Not refereed][Invited]
  
• アノード酸化皮膜のマイクロ・ナノテクノロジー

  菊地竜也, 坂入正敏, 高橋英明  軽金属  61-  373  2011  [Not refereed][Invited]
  
• A Novel Method for Microstructure Fabrication with Anodic Oxide Films

  KIKUCHI Tatsuya, SAKAIRI Masatoshi, YONEZAWA Tetsu, JHA Himendra, TAKAHASHI Hideaki  Jitsumu Hyomen Gijutsu  61-  (2)  207  -207  2010  [Not refereed][Invited]
  
• AST2008国際会議報告 –アノード酸化の新しい世界-

  菊地竜也  表面技術  60-  156  -158  2009  [Not refereed][Invited]
  
• 212th ECS Meeting

  KIKUCHI Tatsuya  Zairyo-to-Kankyo  57-  (4)  186  -187  2008  [Not refereed][Invited]
  
• 2008年3学協会北海道支部研究発表報告

  菊地竜也  Zairyo-to-Kankyo  57-  229  2008  [Not refereed][Invited]
  
• 分岐点

  菊地竜也  まてりあ  43-  251  2004  [Not refereed][Invited]
  
• Micro-Technology on Aluminum Surface with Anodizing, Laser Irradiation, and Electrochemical Technique

  KIKUCHI Tatsuya, SAKAIRI Masatoshi, TAKAHASHI Hideaki  Jitsumu Hyomen Gijutsu  52-  (1)  84  -85  2001  [Not refereed][Not invited]
  
• Fabrication of Metal Micro-Structure with Anodizing of Aluminum and Laser Irradiation - For Development of Novel LIGA Processes-

  Tatsuya KIKUCHI, Song Zhu CHU, Zenta KATO, Masatoshi SAKAIRI, Hideaki TAKAHASHI  J. Surface Fini. Soc. of Japan.  50-  (8)  697  -704  1999  [Not refereed][Not invited]
  

Industrial Property Rights

• 特願2023-117061:アルミニウム材の製造方法  2023年

  岩井愛, 菊地竜也, 中島大希
• 特願2023-103649:構造色部材及びその製造方法  2023年

  菊地竜也, 芦澤来虹, 中島大希
• 特願2023-063321:表面処理アルミニウム材、その製造方法及び半導体処理装置用部材  2023年

  中島大希, 菊地竜也
• 特願2020-118492:アルミニウム部材及びその製造方法  2020年

  菊地竜也, 佐藤美羽, 布村順司, 大谷良行
• 特願2020-193670:チタンの製造方法  2020年

  鈴木亮輔, 野口宏海, 菊地竜也, 堀川松秀, 金子拓実
• 特許5446514:配線基板の製造方法  

  特願2009-155401
• 特許4257676:めっきによる三次元微細構造体の成形法  

  特開2004-091878

Awards & Honors

• 2020 日本鉄鋼協会 ２０２０年度俵論文賞
  
• 2018 日本金属学会 第66回論文賞
  
• 2018 北海道大学 平成29年度教育研究総長表彰
  
• 2016 北海道大学 平成27年度研究総長賞奨励賞
  
• 2015 日本金属学会 第63回論文賞
  
• 2004 表面技術協会 平成16年度進歩賞
  
• 1998 日本金属学会・日本鉄鋼協会 第6回奨学賞
  

Research Grants & Projects

• 塩基を用いた高耐食性アルマイトの創製と超寿命アルミニウム材料への応用

  日本学術振興会：科学研究費補助金（基盤研究（B））

  Date (from‐to) : 2022/04 -2025/03 

  Author : 菊地 竜也
• アルミニウム製水滴発電機の創製

  日本学術振興会：科学研究費補助金（挑戦的研究（萌芽））

  Date (from‐to) : 2022/06 -2024/03 

  Author : 菊地 竜也
• 表面ナノ構造の最適設計に基づく超高耐食性アルミニウム材料の創製

  日本学術振興会：科学研究費補助金（基盤研究（B））

  Date (from‐to) : 2019/04 -2022/03 

  Author : 菊地 竜也
• 高速超親水・超撥水金属材料の創製と熱エネルギー交換デバイスへの応用

  日本学術振興会：科学研究費補助金（基盤研究（B））

  Date (from‐to) : 2016/04 -2019/03 

  Author : 菊地 竜也
• 光学顕微鏡の回折限界を超える高規則配列ナノレンズアレイの創製

  日本学術振興会：科学研究費補助金（挑戦的萌芽研究）

  Date (from‐to) : 2016/04 -2018/03 

  Author : 菊地 竜也
• チタン系電解コンデンサ用マイクロ・ナノ合金微粒子の創成

  日本学術振興会：科学研究費補助金（挑戦的萌芽研究）

  Date (from‐to) : 2013/04 -2015/03 

  Author : 菊地 竜也
• 高規則化ナノレンズアレイの創製と光学的応用

  日本学術振興会：科学研究費補助金（若手研究（A））

  Date (from‐to) : 2012/04 -2015/03 

  Author : 菊地 竜也
• 自己組織化・高密度ナノポーラス金属の創成

  日本学術振興会：科学研究費補助金（挑戦的萌芽研究）

  Date (from‐to) : 2011/04 -2013/03 

  Author : 菊地 竜也
• 環境対応型マイクロアクチュエーターの試作

  日本学術振興会：科学研究費補助金（若手研究（B））

  Date (from‐to) : 2008/04 -2010/03 

  Author : 菊地 竜也
• レーザー照射/電気化学によるアルミニウムの表面微細加工

  日本学術振興会：科学研究費補助金（特別研究員奨励費）

  Date (from‐to) : 2000/04 -2003/03 

  Author : 菊地 竜也

Educational Activities

Teaching Experience

Social Contribution

Social Contribution

Social Contribution

• 北海道大／アルマイトの安全な「超高速剥離法」開発

  Date (from-to) : 2022/08/19

  Role : Others

  Event, Program, Title : 鉄鋼新聞
• 北海道大学、アルマイトの安全な超高速剥離法を開発

  Date (from-to) : 2022/07/28

  Role : Others

  Event, Program, Title : 日刊軽金属
• 北大、ナノ細孔アルマイト薄膜を剥離製造 ナノテク材の工業化加速

  Date (from-to) : 2022/07/28

  Role : Others

  Event, Program, Title : 日刊工業新聞
• アルミニウムのアノード酸化 -基礎と研究紹介-

  Date (from-to) : 2018/12/12

  Role : Lecturer

  Sponser, Organizer, Publisher  : （株）UACJ

  Event, Program, Title : 講演会
• 輝け！ 高専生！ 大学・大学院進学へのご招待

  Date (from-to) : 2018/11/12

  Role : Lecturer

  Sponser, Organizer, Publisher  : 函館工業高等専門学校

  Event, Program, Title : 物質環境工学科講演会
• アルミニウムのアノード酸化の革新を目指して

  Date (from-to) : 2018/08/02

  Role : Lecturer

  Sponser, Organizer, Publisher  : 日本軽金属（株）

  Event, Program, Title : 講演会
• 表面ナノ構造に基づく新規機能性アルミニウム材料の開発

  Date (from-to) : 2018/06/27

  Role : Lecturer

  Sponser, Organizer, Publisher  : 軽金属奨学会

  Event, Program, Title : 軽金属の表面処理と新しい展開 講演会
• アルミニウムのアノード酸化による機能性材料の創製

  Date (from-to) : 2018/04/20

  Role : Lecturer

  Sponser, Organizer, Publisher  : 名古屋大学未来社会創造機構材料電気化学講座

  Event, Program, Title : 講演会
• ナノ構造を制御した機能性アルミニウム材料 —誰でも簡単に、安価に、新しい特性を—

  Date (from-to) : 2017/09/29

  Role : Informant

  Sponser, Organizer, Publisher  : 北海道大学工学部

  Event, Program, Title : 工学系イノベーションフォーラム
• ナノ構造を制御した機能性アルミニウム

  Date (from-to) : 2017/07/27

  Role : Lecturer

  Sponser, Organizer, Publisher  : 北海道経済連合会産業振興委員会

  Event, Program, Title : 講演会
• アルマイトのナノテクノロジー

  Date (from-to) : 2015/08/31

  Role : Lecturer

  Sponser, Organizer, Publisher  : 文部科学省ナノテクノロジープラットフォーム事業 微細構造解析プラットフォーム

  Event, Program, Title : 2015年度第1回ワークショップ
• 特別講評講師

  Date (from-to) : 2014/11/15-2014/11/16

  Role : Lecturer

  Sponser, Organizer, Publisher  : 道内国立高専専攻科

  Event, Program, Title : 平成26年度研究発表・交流会
• マイクロ・ナノテクノロジーの世界 －小さなものを形づくる技術－

  Date (from-to) : 2010/09/11

  Role : Lecturer

  Sponser, Organizer, Publisher  : 北海道大学・稚内高等学校

  Event, Program, Title : 工学セミナー２０１０
• レーザーパターニングによる微細金属構造体形成法の開発

  Date (from-to) : 2009/03/02

  Role : Panelist

  Sponser, Organizer, Publisher  : 北海道大学・北海道

  Event, Program, Title : 産学官連携で地域資源を活かす
• 北大、道工試、微細金属の3次元構造体作製法を開発

  Date (from-to) : 2003/05/02

  Role : Others

  Sponser, Organizer, Publisher  : 日本工業新聞
• 北大など、アルミ表面に3次元微細構造体を加工する新技術

  Date (from-to) : 2002/05/15

  Role : Others

  Sponser, Organizer, Publisher  : 日本工業新聞