Habazaki Hiroki

Faculty of Engineering　Applied Chemistry　Functional Materials ChemistryProfessor
Research Institute for Electronic Science　Green Nanotechnology Research CenterProfessor
Research Institute for Electronic Science　Research Center of Mathematics for Social CreativityProfessor
Office for Integrated Technical Core HubProfessor
Last Updated :2026/02/04

■Researcher basic information

Degree

  • Doctor of Science, Tohoku University

Researchmap personal page

Home Page URL

J-Global ID

Research Keyword

  • Corrosion and Passivity
  • Water splitting
  • Super-liquid repellent and liquid-slippery surfaces
  • Interfacial Electrochemistry
  • Anodizing
  • Nanoporous materials

Research Field

  • Nanotechnology/Materials, Thin-film surfaces and interfaces
  • Nanotechnology/Materials, Energy chemistry
  • Nanotechnology/Materials, Structural and functional materials
  • Nanotechnology/Materials, Nanomaterials

Educational Organization

■Career

Career

  • Apr. 2023 - Present
    Dean of Faculty and School of Engineering, Hokkaido University
  • Apr. 2010 - Present
    Faculty of Engineering, Hokkaido University, Professor
  • Apr. 2016 - Mar. 2019
    Hokkaido University, Center for Advanced Research of Energy and Materials, Faculty of Engineering, Director
  • Apr. 2006 - Mar. 2010
    Graduate School of Engineering, Hokkaido University, Professor
  • Apr. 2000 - Mar. 2006
    Graduate School of Engineering, Hokkaido University, Associate Professor
  • Oct. 2000 - Sep. 2005
    Corrosion and Protection Centre, UMIST, Visiting Researcher
  • Apr. 1988 - Mar. 2000
    Institute for Materials Research, Tohoku University, Research Associate
  • Nov. 1993 - Oct. 1995
    Corrosion and Protection Centre, UMIST, Postdoctoral Researcher

Educational Background

  • Apr. 1986 - Mar. 1988, Tohoku University, Graduate School of Science, Department of Chemistry
  • Apr. 1982 - Mar. 1986, Tohoku University, Faculty of Science, Department of Chemistry

Committee Memberships

  • Jan. 2024 - Present
    the committee of Capacitor Technology, the Electrochemical Society of Japan, Secretary general
  • Apr. 2023 - Present
    北海道工学教育協会, 会長, Society
  • Jan. 2009 - Present
    The Electrochemical Society of Japan, Board Member of the Committee of Capacitor Technology, Society
  • Jan. 1997 - Present
    表面技術協会，金属のアノード酸化皮膜の機能化部会, 幹事, Society
  • Jan. 2023 - Dec. 2024
    International Society of Electrochemistry, Division Chair, Society
  • Mar. 2022 - Feb. 2024
    The Surface Finishing Society of Japan, Vice-President, Society
  • Jan. 2010 - Dec. 2023
    固体イオニクス学会, 役員, Society
  • Mar. 2019 - Mar. 2021
    電気化学会, 理事, Society
  • Jan. 2016 - Dec. 2019
    表面技術協会 アノード酸化皮膜の機能化部会, 代表幹事, Society
  • Mar. 2018 - Feb. 2019
    表面技術協会, 編集委員長, Society
  • Jan. 2017 - Dec. 2018
    電気化学会, 北海道支部長, Society
  • Jan. 2015 - Dec. 2016
    表面技術協会, 北海道支部長, Society
  • Jan. 2013 - Dec. 2014
    腐食防食学会, 北海道支部長, Society
  • Jan. 2010 - Dec. 2012
    腐食防食協会, 北海道支部副支部長, Society
  • 2010 - 2011
    Internationa Society of Electrochemistry, シンポジウムオーガナイザー, Society
  • 2009 - 2011
    電気化学会, 編集委員, Society
  • 2009 - 2010
    Internationaｌ Society of Electrochemistry, シンポジウムオーガナイザー, Society
  • Apr. 2005 - Mar. 2009
    表面技術協会, 「表面技術」編集委員, Society

Position History

  • 教育研究評議会評議員, 2019年4月1日 - 2021年3月31日
  • 教育研究評議会評議員, 2021年4月1日 - 2023年3月31日
  • 工学部長, 2023年4月1日 - 2025年3月31日
  • 大学院工学研究院長, 2023年4月1日 - 2025年3月31日
  • 大学院工学研究院附属エネルギー・マテリアル融合領域研究センター長, 2016年4月1日 - 2017年3月31日
  • 大学院工学研究院附属エネルギー・マテリアル融合領域研究センター長, 2017年4月1日 - 2019年3月31日
  • 大学院工学研究院副研究院長, 2019年4月1日 - 2021年3月31日
  • 大学院工学研究院副研究院長, 2021年4月1日 - 2023年3月31日
  • 評価室室員, 2018年7月1日 - 2020年6月30日
  • 評価室室員, 2020年7月1日 - 2022年6月30日
  • 評価室室員, 2022年7月1日 - 2023年3月31日

■Research activity information

Awards

  • Mar. 2020, The Electrochemical Society of Japan, Fellow　　　　　　　　　　　　　　　
  • Feb. 2020, 北海道大学, 教育研究総長表彰　　　　　　　　　　　　　　　
  • Mar. 2019, The Electrochemical Society of Japan, Best Paper Award　　　　　　　　　　　　　　　
    辻 悦司;松浦 志紀;青木 芳尚;幅崎 浩樹
  • Mar. 2013, ECSJ Award of Scientific Excellence　　　　　　　　　　　　　　　
    幅崎 浩樹
  • Mar. 2005, JSPS, JSPS Prize　　　　　　　　　　　　　　　
    幅崎 浩樹
  • Sep. 1997, Institute of Corrosion, T.P. Hoar Award　　　　　　　　　　　　　　　
    HABAZAKI Hiroki

Papers

Other Activities and Achievements

Books and other publications

  • Shreir's Corrosion　　　　　　　　　　　　　　　
    Elsevier, 2009

Affiliated academic society

  • 固体イオニクス学会　　　　　　　　　　　　　　　
  • 表面技術協会　　　　　　　　　　　　　　　
  • 腐食防食学会　　　　　　　　　　　　　　　
  • 日本金属学会　　　　　　　　　　　　　　　
  • 日本化学会　　　　　　　　　　　　　　　
  • 電気化学会　　　　　　　　　　　　　　　
  • 炭素材料学会　　　　　　　　　　　　　　　
  • The Electrochemical Society　　　　　　　　　　　　　　　
  • Internationa Society of Electrochemistry　　　　　　　　　　　　　　　
  • 日本工学アカデミー　　　　　　　　　　　　　　　
  • 日本鉄鋼協会　　　　　　　　　　　　　　　

Research Themes

  • Novel preparation of highly active iron-based alloy electrodes by anodic oxidation and their activation mechanism
    Grants-in-Aid for Scientific Research
    01 Apr. 2023 - 31 Mar. 2027
    幅崎 浩樹, 北野 翔
    金属のアノード酸化法は、金属・合金上に多孔質酸化膜を簡便に形成できる優れた手法であり、アルミニウムなどでは工業的に広く使われている。研究代表者らは、このアノード酸化法をFeNi系合金に適応した場合、アルカリ水電解用酸素発生電極としての活性および耐久性が大幅に改善されることを見出している。本研究ではその活性化の機構の解明と高活性電極の設計指針の確立を目指すものである。
    本年度は実用FeNi合金であるFe-54 mass% Co-17 mass% Ni合金（Kovar合金）、Fe-45 mass％Ni合金（45 Permalloy合金)、Fe-42 mass% Ni(42Invar合金)、Fe-78 mass% Ni（78 Permalloy合金)を試料としてアノード酸化をフッ化物含有エチレングリコール溶液中において行い、そのアノード酸化膜の解析を進めるとともにOER特性を評価し、Kovar合金が最も優れた酸素発生反応（OER）活性を示すことを確認した。
    さらに、そのアノード酸化後のKOH水溶液中にお行ける酸化膜の構造変化をその場観察するために、in situ Raman測定法の確立を行った。その場観察用に自作の電気化学セルを開発し、in situ Raman測定が可能な環境を確立した。また、予備測定から、アノード酸化で生成したフッ化物相がKOH浸漬に伴い、オキシ水酸化物とスピネル酸化物の混合層へと変化し、このスピネス酸化物相は酸素発生する貴な電位域では消失することが明らかとなった。
    また、高活性相と推定されるオキシ水酸化物の結晶性がOERにどのように影響するかを明らかにするために、水熱処理による高結晶性相の形成の試みに着手した。
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 23H00224
  • 高性能・小次世代高電力密度パワエレ機器に向けた高性能コンデンサの研究開発　　　　　　　　　　　　　　　
    革新的パワーエレクトロニクス創出基盤技術研究開発事業
    2021 - 2025
    文部科学省, 北海道大学, Principal investigator
  • 汎用合金のアノード酸化による高活性・高耐久水電解電極の開発
    産学が連携した研究開発成果の展開 研究成果展開事業 研究成果最適展開支援プログラム(A-STEP) トライアウト トライアウト
    2022 - 2023
    幅崎 浩樹
    本研究開発では高効率な水素製造を可能とするために、集電体ともなりうる各種FeNiおよびFeNiCo実用合金のアノード酸化によって、アルカリ水電解による酸素発生反応および水素発生反応を活性化し、0.6Acm-2の電流において0.35V以下の過電圧を1か月保持できるか検証し、ライフサイクルコストの低い実用的水素製造用電極の開発を目指す。
    科学技術振興機構, 北海道大学, Principal investigator
  • Development of magnesium current collectors with high corrosion resistance at high voltages
    Grants-in-Aid for Scientific Research
    30 Jul. 2020 - 31 Mar. 2022
    Habazaki Hiroki
    In this study, to clarify the possibility of a magnesium cathode current collector in environments containing fluoride ions for lithium-ion batteries, the stability of magnesium in various electrolyte solutions for lithium-ion batteries at high potentials was investigated. As a result, in the LiPF6-based electrolyte, magnesium can be passivated up to about 4 V vs Li+/Li, and is deactivated at higher potentials. Surface analysis suggests that this is due to the inability to form a stable passivation film composed of MgF2 in this environment. On the other hand, when the stability was evaluated using the electrolyte for the fluoride shuttle battery, it was found that no de-passivation occurred up to 10 V.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Hokkaido University, 20K21230
  • Tailoring of highly active amorphous oxide electrodes derived from anodizing of iron-base alloys
    Grants-in-Aid for Scientific Research
    01 Apr. 2019 - 31 Mar. 2022
    Habazaki Hiroki
    Highly efficient hydrogen production by alkaline water electrolysis is an important process for achieving carbon neutrality. In this study, we found that the overpotential of the oxygen evolution reaction in KOH solution can be significantly reduced by simple anodic oxidation of commercially available FeNiCo and FeNi alloys, and that the electrode has excellent durability. It was also found that the porous fluoride layer formed by anodic oxidation is an excellent precursor that is quickly converted to highly active oxyhydroxides in KOH.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 19H02469
  • Preparation of highly active and durable oxygen electrodes using carbon nanofibers with a unique orientation
    Grants-in-Aid for Scientific Research
    01 Apr. 2016 - 31 Mar. 2019
    Habazaki Hiroki, Kowalski Damian, Aoki Yoshitaka, Zhu Chunyu, Yamada Naohito, Sakashita Ryosuke, Sato Yuki
    In this study, platelet-type carbon nanofibers (pCNF) were prepared using porous anodic alumina template with many cylindrical nanopore channels and Co3O4 nanoparticles were deposited on pCNF for tailoring highly active and durable oxygen reduction and oxygen evolution reactions that would be required to develop next-generation fuel cells and metal-air batteries. We found that Co3O4 nanoparticles were uniformly dispersed on pCNF that has exposed carbon edge plane at the side wall of pCNF, and the Co3O4/pCNF exhibited a good oxygen reduction reaction activity. In contrast, poor dispersion of Co3O4 was found on multi-walled carbon nanotubes, in which basal planes of carbon were exposed on the side wall. Through this study, we found the importance of carbon surface structure on the dispersion of oxide nanoparticles and electrocatalytic activities.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 16H04530
  • Tailoring of superoleophobic stainless steel surfaces
    Grants-in-Aid for Scientific Research
    01 Apr. 2015 - 31 Mar. 2017
    Habazaki Hiroki, TSUJI Etsushi
    Fabrication of anti-fouling and ice-phobic surfaces on practical metallic materials, such as stainless steels, is of importance in daily life and for industrial applications. In this study, we successfully fabricated superhydrophobic and superoleophobic surfaces on stainless steel. The surfaces were obtained by preparing the hierarchical micro-/nano-scale rough surfaces, and the roughness was introduced by single chemical or electrochemical etching of stainless steel and following novel anodizing technique.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 15K14171
  • High strength and high corrosion resistant Mg alloys designed using a heterogeneity integration method
    Grants-in-Aid for Scientific Research
    01 Apr. 2013 - 31 Mar. 2016
    Yamasaki Michiaki, HABAZAKI Hiroki, MAYAMA Tsuyoshi
    I have sought to design multifunctional Mg alloys with synchronized LPSO phase, using heterogeneity integration method that considers geometrical and electrochemical viewpoints. The microstructure of extruded Mg/LPSO two-phase alloys is characterized by a multimodal microstructure; fine DRXed alpha-Mg grains with random orientation and coarse alpha-Mg grains with strong fiber-texture. The LPSO phase grains also develop string fiber texture. While the fine DRXed region contributes to the improvement in ductility, the coarse grains and LPSO phase contribute to its increased mechanical strength. From the viewpoint of corrosion science, the LPSO phase may be considered as a secondary phase causing a potential difference between phases. Controlling the Volta potential through chemical composition design of the LPSO phase is effective for reducing the potential difference. Al addition to the Mg/LPSO two-phase alloy is effective for reduction of potential difference.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Kumamoto University, 25289251
  • Development of laser-assisted anodizing technique for lightweight alloys
    Grants-in-Aid for Scientific Research
    01 Apr. 2013 - 31 Mar. 2015
    YAMASAKI Michiaki, OTSU Masaaki, HABAZAKI Hiroki
    In order to establish a laser-assisted anodizing technique for Mg-Zn-rare earth Mg/LPSO two-phase alloys, fundamental studies for development of an anodizing process and a laser-irradiation process were performed. (1) Development of novel anodizing technique using Na2SiO3-alkali-soution: Si-containing oxide films were fabricated on the surface of Mg-Zn-rare earth Mg/LPSO two-phase alloys by anodizing technique using Na2SiO3-alkali-soution. (2) Development of laser-irradiation technique: Anti-corrosive MgO surface films were fabricated on the surface of Mg-Zn-rare earth Mg/LPSO two-phase alloys by conversion technique from hydroxide to oxide using laser irradiation.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Kumamoto University, 25630295
  • Fabrication of intermediate temperature fuel cells using proton conducting anodic oxide film as a novel solud electrolyte
    Grants-in-Aid for Scientific Research
    01 Apr. 2012 - 31 Mar. 2015
    HABAZAKI HIROKI, AOKI Yoshitaka, TSUJI Etsushi
    IIn this study, we investigated the fabrication of membrane-electrode assembly using proton conductive anodic ZrO2-WO3 or ZrO2-WO3-SiO2 nanofilms, which were developed by us, for intermediate temperature fuel cells operating below ~300 degre C. Hydrogen permeable anode foils have been utilized as a support of the proton conducting nanofilms and several fabrication processes have been proposed and examined. We succeeded to generate power. Further, by modifying the anodizing process to form the proton conducting anodic films, we have increased the proton conductivity by nearly one order of magnitude.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 24360298
  • 実用金属表面の超撥水・超撥油化
    産学が連携した研究開発成果の展開 研究成果展開事業 研究成果最適展開支援プログラム(A-STEP) 探索タイプ
    2013 - 2013
    幅崎 浩樹
    アルミニウムの1化学エッチングによるマイクロピット表面の形成,2そのアノード酸化によるナノポーラス酸化膜の形成とポアワイドニングによるポア径・多孔度の調整,3表面のフルオロアルキルコーティングによる表面自由エネルギーの低減の組み合わせにより,表面張力22 mN m-1のオクタンをも弾く超撥油表面を達成した。さらにアルミニウム板の代わりにアルミニウムメッシュを用いることによりヘキサン(表面張力18 mN m-1)にも全く濡れない表面となり,ほぼあらゆる液体に汚れないアルミニウム表面を実現できた。ステンレス鋼についても電解エッチングとアノード酸化の組み合わせにより菜種油を弾く超撥油表面を得ることができた。
    北海道大学
  • アノード酸化による色素増感太陽電池用メソポーラスチタニア膜の合成
    産学が連携した研究開発成果の展開 研究成果展開事業 研究成果最適展開支援プログラム(A-STEP) 探索タイプ
    2011 - 2012
    幅崎 浩樹
    本研究ではスパッタとアノード酸化を組合わすことにより、熱処理なしで高結晶性メソポーラスTiO2膜を合成し、色素増感太陽電池の高性能化を図ることを目標とする。ITO透明導電性ガラス上にスパッタ成膜したTi薄膜を160°Cのリン酸含有グリセリン溶液中でアノード酸化することで、熱処理なしにアナターゼ型TiO2薄膜の作製に成功した。また、液性の異なるリン酸含有グリセリン溶液中でアノード酸化することにより、酸性度がその結晶性に大きく影響することを見出した。このTiO2膜を用いた色素増感太陽電池を実際に組むことで、これまで報告されている熱処理後のTiO2ナノチューブ薄膜を用いたものよりも優れた特性を示すことを明らかにした。今後は、これらの知見をもとにより熱処理なしでより高結晶性のTiO2薄膜を作製し、応用展開する予定である。
    北海道大学
  • Electrochemical Synthesis of Proton-conducting Oxide Nanofilms forIntermediate-temperature Fuel Cells
    Grants-in-Aid for Scientific Research
    2011 - 2012
    HABAZAKI Hiroki, AOKI Yoshitaka, TSUJI Etsushi
    Nobel proton-conducting oxide thin films were fabricated by simple anodizing technique for possible application as an solid electrolyte for intermediate-temperature fuel cells. The amorphous ZrO2-WO3-SiO2 films formed by anodizing revealed the proton conductivity sufficient for the fuel cell application at ~200oC. In addition, the oxide films showed unique thickness-dependent conductivity with theconductivity highly enhanced by reducing the film thickness less than 300 nm.
    Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 23656441
  • 中温域燃料電池用プロトン伝導性電解質ナノ膜の技術開発
    産学が連携した研究開発成果の展開 研究成果展開事業 研究成果最適展開支援プログラム(A-STEP) 探索タイプ
    2010 - 2010
    幅崎 浩樹
    次世代中温域燃料電池用電解質として期待される、プロトン伝導性ZrO2-WO3ナノ薄膜の技術開発を行った。種々の組成のZr-W合金上にアノード酸化ZrO2-WO3皮膜を形成したところ、タングステン添加量を増大させるとプロトン伝導性が一層向上することが明らかとなった。また、このアノード酸化皮膜はプロトン伝導率の膜厚依存性を示し、伝導率が増大する遷移膜厚がタングステン添加量の増大によって厚膜側へとシフトすることを明らかとした。このZrO2-WO3ナノ膜をITO基板上に形成するとさらに一桁以上伝導率の向上し、電解質膜として有望であることが確認された。しかしながら、MEAとした場合、新たに界面抵抗を低減する必要性が明らかとなった。
    北海道大学
  • 軽金属上への超撥水・超撥油性表面の創製
    科学研究費助成事業
    2009 - 2010
    幅崎 浩樹
    本研究では,アルミニウムやチタンなどの軽金属表面にアノード酸化をいう簡便な手法により,表面形態を制御した多孔質酸化皮膜を形成し,超撥水・超撥油性表面を創製することを目的とした。超撥水および超撥油表面を創製するには,表面エネルギーが小さくなるように表面組成を制御するとともに,表面粗さを導入する必要がある。特に階層構造をもった多孔質表面が表面を超撥水化するのに必要となる。
    階層構造表面を形成するために,まず,斜入射マグネトロンスパッタ法(OAD)とアノード酸化法を組み合わせた。アルミニウム上にOADによりサブミクロンサイズのAl-Nb合金カラム構造を得,さらにアノード酸化によりナノボアを導入した。酸化物表面は親水性であるので,現在知られている物質で最も表面エネルギーを小さくできるCF_3基を末端に持つフルオロアルキルリン酸単分子層で表面をコーティングした。その結果,超撥水のみならず,超撥油性までも発現することができた。この研究を通して,超撥油性を達成するには,階層構造を精密に制御する必要があることがわかり,特にサブミクロンカラム間のギャップサイズの制御が重要であることを明らかにした。
    一方,アノード酸化のみにより,階層構造を形成する手法の開拓として,ニオブのアノード酸化を行った。高温のリン酸塩含有グリセリン溶液中におけるアノード酸化により,マイクロコーン上の表面形態をしたナノポーラス皮膜が得られる。このコーンサイズやナノ構造をアノード酸化電圧や電解液中の水分量で制御でき,サイズが大きく,コーンの先端角が小さいほど,水の接触角が大きくなることがわかった。その結果,175°という極めて大きな接触角を持つ超撥水表面を得ることができた。
    日本学術振興会, 挑戦的萌芽研究, 北海道大学, 21656180
  • Plasma electrolytic oxidation of light metals : elucidation of the process and surface functionalization
    Grants-in-Aid for Scientific Research
    2007 - 2010
    HABAZAKI Hiroki, FUSHIMI Koji, AOKI Yoshitaka
    Plasma electrolytic oxidation (PEO) is an attractive process to form ceramics coatings on light metals, including magnesium, aluminum and titanium, in aqueous electrolytes at ambient temperature. The present study discloses the excellent healing properties of discharge channels in alkaline silicate electrolyte. Further, novel two-step PEO process is developed to form wear-resistant and highly adherent ceramics coating on β-Ti alloy with high mechanical strength and cold workability.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 19206077
  • グロー放電発光分光法による耐食表面の高分解能解析法の確立
    科学研究費助成事業
    2007 - 2008
    幅崎 浩樹, 伏見 公志
    グロー放電発光分光法(GDOES)がナノ薄膜の迅速分析法として有効であることを示し, 高分解能デプスプロファイルを得るための手法を確立する研究を推進した。まず, 耐海水ステンレス鋼であるSUS312L鋼を用いて, 異なる粒径のアルミナ研磨液を用いて試料を鏡面研磨した。その表面粗さを原子間力顕微鏡(AFM)を用いて計測し, GDOES分析における深さ分解能との相関関係を調べた。研磨条件によりステンレス鋼上に生成する大気酸化皮膜の厚さや組成が変化する可能性があるので, 深さ分解能の評価としてその皮膜直下に存在する銅濃縮層を指標として用いた。GDOESプロファイル上の界面濃縮層の銅のピークの半値幅は表面粗さの対数に対して直線的に変化し, 表面粗さの分解能の影響がきわめて大きいことを明らかにした。同じ鏡面研磨でも表面粗さをできるだけ低減することがナノ薄膜の分析において, 高い深さ分解能を得る上で重要であることを示した。
    また, 従来のX線光電子分光法やオージェ電子分光法などの表面分析法では, 感度が低く, 塩化物イオン含有水溶液中で生成した不動態皮膜中の塩化物イオンをGDOESを用いることで検出できた。塩化物イオンは不動態皮膜中の鉄リッチな皮膜外層にのみ存在しており, クロムリッチな皮膜内層には達していないことを示すことができた。
    以上のように, ステンレス鋼の不動態皮膜や大気酸化皮膜のような厚さ2-3nm程度の表面酸化皮膜でも, 十分に表面を平滑にした試料を用いることで, 高分解能, 高感度で分析できる手法を確立できた。
    日本学術振興会, 萌芽研究, 北海道大学, 19656184
  • プラズマ陽極酸化による軽量・高強度チタン合金への耐魔耗性コーティング
    産学が連携した研究開発成果の展開 研究成果展開事業 地域事業 地域イノベーション創出総合支援事業 シーズ発掘試験
    2007 - 2007
    幅崎 浩樹
    火花放電(プラズマ)を伴う陽極酸化プロセスにより,通常高温でなければ生成しない硬質なセラミックス酸化物を常温の水溶液中においてチタン合金上に密着性良く生成する。本技術によりチタン合金の耐摩耗性の大幅な改善を目指す。
    北海道大学, Principal investigator
  • Structural control and self-organization of the functional oxide films formed on titanium
    Grants-in-Aid for Scientific Research
    2004 - 2006
    HABAZAKI Hiroki, FUSHIMI Koji, KONNO Hidetaka
    1.Formation of self-organized porous anodic oxide
    We have successfully developed self-organized porous anodic oxide films on Ti-Si alloys in hot glycerol solution containing dibasic phosphate. The key issue for the formation of the porous films is suppression of the crystallization of anodic oxide, which induces gas evolution during anodic film growth. The similar porous films are also developed on niobium and aluminum substrates. The cell size of the porous films on aluminum is dependent upon the formation voltage, similar to those formed in acid aqueous solutions.
    2.Formation of barrier-type anodic oxide with excellent dielectric properties
    Incorporation of foreign species from substrate suppresses effectively the development of crystalline anodic oxide on titanium. By increasing alloying element content, the structure of the air-formed film present before anodizing is modified, such that growth of amorphous oxide continues to higher formation voltages. The compositional dependence of the dielectric properties of anodic oxides formed on a range of titanium alloys has been examined systematically.
    3.Hard coating of titanium alloys by spark anodizing
    Spark anodizing of titanium, Ti-6Al-4V and Ti-15V-3Al-3Cr-3Sn has been performed in alkarine electrolyte containing aluminate and phosphate. Highly crystalline Al2TiO5-based oxide coatings,〜20μm thick, have been developed by dc-biased ac anodizing to high voltages. Regardless of the materials used, the coatings with hardnes of 〜6GPa have been obtained. The coatings have porosity, associated with discharge channel. From optical measurements during spark anodizing, the temperature at the discharge region has been estimated to be 4500〜5000℃. Such high temperature allows us to develop the highly crystalline coatings with high concentration of electrolyte species even in an aqueous solution at ambient temperature.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), HOKKAIDO UNIVERSITY, 16360353
  • 配向制御ナノ・マイクロカーボンの液相テンプレート合成
    科学研究費助成事業
    2004 - 2005
    幅崎 浩樹, 金野 英隆
    ポリ塩化ビニル(PVC)と多孔質アノード酸化アルミナテンプレートから液相鋳型炭素化で得られるカーボンナノファイバーの構造について,詳細な検討を行った。まず,600℃の低温熱処理の段階でファイバー軸方向への炭素の層の積層が確認され,PVCがピッチ状になった段階で生成している多環芳香族化合物がface-onの配向を持ってアルミナと相互作用することがこのような配向の生成原因であることが示唆された。
    また,2800℃〜3000℃の熱処理によりカーボンナノファイバーの側面に炭素の層5層程度からなるループの形成が確認され,TEMによる試料の傾斜観察からファイバーの螺旋構造の可能性もあることが示された。
    このような熱処理による構造の変化およびファイバー径のリチウムイオン二次電池の負極特性との関連を検討した。1000℃熱処理した試料の可逆容量が大きく,1500および2800℃熱処理した試料の可逆容量は200mAhg^<-1>程度しかなかった。黒鉛化している2800℃熱処理試料の容量が通常の黒鉛材料(理論容量372mAhg^<-1>)よりもかなり小さいのは,ループの生成が関係している可能性が大である。1000℃熱処理試料では,充放電電流密度を増大させても容量の低下は小さく,特にファイバー径が小さいときに容量の低下が小さくなる傾向が見られた。これは,径を小さくすることでインターカレーションしたリチウムイオンの炭素内での拡散距離が短くなることと対応しているものと考えられる。
    日本学術振興会, 萌芽研究, 北海道大学, 16651053
  • Synthesis of Laminated Graphite Nano-composites Using Exfoliated Graphite
    Grants-in-Aid for Scientific Research
    2001 - 2003
    KONNO Hidetaka, HABAZAKI Hiroki
    Exfoliated graphite has very large sorption capacity for oils. Utilizing this property, various metal complexes, silicone compounds, metal alkoxides and others were impregnated into exfoliated graphite, and pretreated, mainly by heat treatment in air or hydrolysis in water vapor, to form precursors. By heating these precursors in an inert atmosphere, the following multi-functional carbonaceous materials were synthesized.
    (1) Ni/graphite composite, Fe/graphite composite, Fe_3O_4/graphite composite (potential applications : magnetic materials, absorber for electromagnetic radiation, catalyst, and so on)
    (2) Graphite coated with ultra thin Si-C-O composites (oxidation resistant carbon material, conductive materials at high temperatures)
    (3) Mn2O3 or MnO2/graphite composite (electrode materials for super capacitors)
    (4) Nano-particles of single or multi-component metal carbides, such as β-SiC, TiC, ZrC, (Ti,Zr)C and others.
    The developed method to synthesize (4) is promising as an industrial process because it is simple and low cost.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 13450279
  • Tailoring of Oxidation-Resistant Nb-base Alloys at Ultra-High Temperatures and Understanding of their Oxidation Mechanism
    Grants-in-Aid for Scientific Research
    2001 - 2002
    HABAZAKI Hiroki
    Sputter-deposited Nb alloys containing both aluminum and chromium reveal high oxidation resistance above 1073 K, in contrast to less oxidation-resistant Nb-Al and Nb-Cr binary alloys. The oxidation of the ternary alloys generally follows the parabolic rate law, indicating that diffusional transport of matter is the rate-determining step. However, the high oxidation resistance of the ternary alloys containing about 40 at% niobium is not due to the formation of an alumina scale, but due to an outer chromia layer with the inner layer consisting of a mixture of alumina, chromium-niobium and/or aluminum-niobium double oxides. When the ternary alloys containing about 40 at% niobium were oxidized in O_2-SO_2 atmospheres, preferential oxidation of aluminum occurs as a consequence of a transient sulfidation of aluminum at the alloy/scale interface. However, the preferential oxidation results in internal oxidation of the alloys, not in the formation of continuous external alumina scale. Further increase in aluminum content by reducing niobium content, finally results in the formation of highly protective α-alumina scales above 1073 K. Coating of this aluminum-rich niobium alloy to niobium-base alloys with high mechanical properties at high temperatures may induce interdiffusion between the coating and substrate, leading to degradation of the oxidation resistance. The authors have successfully demonstrated that introduction of an anodic alumina layer between the coating and substrate as a diffusion barrier layer suppresses effectively the interdiffusion, thus high oxidation resistance of the coating is sustained at high temperatures.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), HOKKAIDO UNIVERSITY, 13650770
  • DEVELOPMENT OF NOVEL MATERIALS FOR ENVIRONMENTAL PROTECTION AND ENERGY SUPPLY GLOBAL CARBON DIOXIDE RECYCLING
    Grants-in-Aid for Scientific Research
    1998 - 2001
    ASAMI Katsuhiko, SHIMAMURA Kazuo, KIKUCHI Michio, KAWASHIMA Asahi, KUMAGAI Naokazu
    We are proposing a CO_2 recycling system for preventing global warming caused by CO_2 emissions in conjunctions with development of human activities. The system consists of methanation of CO_2 which are recovered at fuel consumers sites such as power plants. Methanation needs highly active catalysts and hydrogen which can be obtained from seawater electrolysis using solar energy. To substantiate this system in global scale, we need to develop low cost catalysts and electrode with high efficiency for hydrogen evolution and oxygen evolution reactions at seawater electrolysis. The objectives of this investigation are to develop such new catalysts and electrode substances.
    Comparison between Ni-Mo and Ni-Mo-O alloy electrodes fabricated on Ni substrate showed existence of small amount of O imparts both higher activity for hydrogen evolution reaction and higher durability. Another electrode candidate was Ni-Fe-C alloy system. It showed almost no increase in hydrogen overpotential even after accelerating test for two years at a high current density of 50,000 A/m^2. It was also stable and suffered no corrosion even after repeated stoppage of electrolysis in a concentrated NaOH solution at high temperature.
    For the first time in the world, we have succeeded in preparation of electrodes with 100 % oxygen evolution efficiency for seawater electrolysis using MnO_2 type oxide electrode installed on titanium substrate. It was also found combined addition of Mo and W was more effective for selective oxygen evolution at seawater electrolysis and we were able to reduce electrolysis voltage successfully.
    Moreover, we found methanation catalysts prepared from amorphous Ni-Zr alloys had high activity sfpr methanation. We have also succeeded in develop more active catalyst using amorphous Ni-Zr-Sm alloys as precursors of the catalysts. It was clarified that samarium stabilize tetragonal phase of zirconia on which dispersion of Ni particles were also enhanced.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Tohoku University, 10355027
  • Preparation of Corrosion-Resistant Bulk Amorphous Alloys
    Grants-in-Aid for Scientific Research
    1999 - 2000
    HABAZAKI Hiroki
    Corrosion-resistant bulk Ni-Cr-Nb-P-B, Ni-Cr-Ta-P-B and Ni-Cr-Me-P-B alloys with cylindrical shape of 1 and 2 mm diameter are prepared by a copper mold casting method. A good correlation between the glass forming ability and stability of super-cooled liquid state has been found for these alloy systems except the molybdenum-containing alloy system. The bulk amorphous alloys thus prepared are spontaneously passive even in very aggressive 6M and 12M HCl solutions open to air at 303 K.The bulk amorphous alloys reveal the same anodic and cathodic polarization curves as the corresponding melt-spun alloy ribbons, as far as amorphous single phase alloys are obtained. Precipitation of fcc Ni phase in the bulk amorphous alloys is detrimental to the corrosion resistance of the alloys. The influence of the precipitation is, however, strongly dependent upon the size of the precipitates. When fcc Ni with size of 20〜nm is formed in the amorphous matrix, the alloys show about two orders of magnitude higher passive current density in comparison with the amorphous single phase alloys. In contrast, precipitation of fcc Ni with only 2-3 nm size results in the increase only twice in the passive current density. Bulk amorphous Ni-10Cr-5Nb-16P-4B alloy plates of 2 mm thickness are also prepared by consolidation of gas-atomized amorphous alloy powders by sheath rolling at a super-cooled liquid state, that is, 708 K.The bulk alloy thus prepared is found to reveal similar extremely low corrosion rate in 6M HCl at 303 K to the corresponding melt-spun alloy. However, in 12M HCl solution, the sheath-rolled alloy shows preferential corrosion attack at boundaries of the gas-atomized powders, possibly due to the influence of the oxidation of the particle surface during heating for consolidation. Thus, further improvement of the preparation processes to obtain highly corrosion-resistant bulk amorphous alloys using this method.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), 11650731
  • TAILORING NOVEL MATERIALS FOR GLOBAL CO_2 RECYCLING
    Grants-in-Aid for Scientific Research
    1998 - 2000
    ASAMI Katsuhiko, KIKUCHI Michio, KAWASHIMA Asahi
    We are proposing a CO_2 recycling system for preventing global warming caused by CO_2 emissions in conjunctions with development of human activities. The system contsists of methanation of CO_2 which are recovered at fuel consumers sites such as power plants. Methanation needs highly active catalysts and hydrogen which can be obtained from seawater electrolysis using solar energy. To substantiate this system global scale, we need to develop low cost catalysts and electrode with high efficiency for hydrogen evolution and oxygen evolution reactions at seawater electrolysis. The objectives of this investigation are to develop such new catalysts and electrode substances.
    We have found methanation catalysts prepared from amorphous Ni-Zr alloys have high activity for methanation. We have also succeeded in develop more active catalyst using amorphous Ni-Zr-Sm alloys as precursors of the catalysts. It was clarified that samarium stabilize tetragonal phase of zirconia on which dispersion of Ni particles are also enhanced. Catalysts prepared from gas-atomized Ni-Zr-Sm alloys also had high activity.
    Ni-Mo and Co-Al-Mo alloy electrode fabricated by sputter-deposition showed high activity for hydrogen evolution reaction. By using arc-ion-plating method, not only adhesiveness to the substrate but also hydrogen evolution efficiency of Ni-Mo alloy electrode was improved ; the most effective composition was Ni-(10-20)at%Mo-(5-10)at%O with the overpotential for hydrogen evolution lower than 100 mV at the cuurent density of 4×10^3A/m^2.
    It was succeeded to prepare an electrode with 100% oxygen evolution efficiency for seawater electrolysis using MnO_2 type oxide electrode installed on titanium stubstrate. The structure of the prepared electrode consisted of chemically homogeneous nanocrystalline manganese oxide with γ-MnO_2 structure containing solid-solved hexavalent tungsten. It was also found combined addition of Mo and W is more effective for selective oxygen evolution at seawater electrolysis and we were able to reduce electrolysis voltage successfully.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B)., Tohoku University, 10044118
  • PREPARATION AND CHARACTERIZATION OF SURFACE CONTROLLED FUNCTIONAL MATERIALS USING NON-EQUILIBRIUM ALLOYS AS THEIR PRECURSORS
    Grants-in-Aid for Scientific Research
    1997 - 1999
    ASAMI Katsuhiko, HABAZAKI Hiroki, KIKUCHI Michio
    1. Ni catalysts supported by zirconia, which have high activity for the reaction for methanation of carbon dioxide with hydrogen, were prepared from amorphous Ni-Zr alloys, and evaluated their activity in relation with alloy composition, reaction temperature. It was found that their activity was highest when they have prepared from Ni-Zr alloys containing Zr from 40 to 50at%Zr. The origin of the alloy composition dependence was explained by the alloy composition dependence of dispersion of metallic Ni on the catalyst surface, turnover number, and the relative concentration of tetragonal zirconia in the support. On the base of the above results, catalysts with higher activity were prepared by addition of a certain amount of Sm which caused stabilization of tetragonal phase of zirconia and increase of Ni dispersion on zirconia.
    2. Non-equilibrium Nb-W and Nb-Mn alloys were prepared by sputtering method. They showed amorphous structure within the composition range of 20-50at%W and 26-75at%Mn, respectively. Their corrosion resistance and surface compositions were evaluated by electrochemical measurements and photoelectron spectroscopy.
    3. Co-20at%Al alloy prepared by sputtering method was a non-equilibrium metallic compound with CsCl-type structure. When alloy films were prepared by reactive sputtering in NィイD22ィエD2 and OィイD22ィエD2 containing atmosphere, they showed ferromagnetic property with high performance even at high frequency region. It was clarified that they were composed of nano-particles of Co surrounded by insulating AlN and AlィイD22ィエD2OィイD23ィエD2, respectively.
    4. Sr-Bi-Ta oxides prepared by sol-gel method followed by annealing at low temperatures showed no ferroelectric properties. But they become ferroelectric substance at high temperature annealing. Their performance was, however, dependent on annealing temperature and atmosphere during annealing. It was made clear that deviation of surface composition from stoichiometry and existence of metallic Bi were harmful to ferroelectric performance.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), TOHOKU UNIVERSITY, 09650776
  • Investigation of electrocatalysts for CO_2 reduction to methane using gas-diffusion electrode and mechanism of enhanced activity
    Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    1997 - 1998
    KAWASHIMA Asahi, HABAZAKI Hiroki
    First of all, we have compared the steady state conventional potentiostatic method with pulsed method in the electrochemical reduction of CO_2. It was found that the faradaic efficiencies for the pulsed electroreduction ofCO_2 to methane and ethylene using copper electrode are higher than those for the potentiostatic reduction and more stable in a long-term electrolysis. In the next study, we have made various electrolysis from copper-based alloys and examined the faradaic efficiencies for methane and ethylene production from CO_2 reduction using pulsed electrolysis in CO_2 saturated 0.1 M KHCO_3 solution at room temperature. Amorphous Cu-Zr and Cu-Tialloy electrodes were prepared using a single-roller melt-spinning method. The sputtering method was applied to prepare Cu-Ag alloys. The amorphous Cu-(30, 40, 60)Zr and Cu-30Ti alloys showed considerably low faradaic efficiencies for methane and ethylene production and both efficiencies were less than 3 %. The sputter-deposited crystalline Cu-Ag alloy electrodes, when the alloys contain small amount of Ag (5-7at%), have a higher faradaic efficiency of methane in comparison with pure Cu electrode. However, excess amount of Ag was detrimental. Although methane and ethylene were not detected on pure Ag electrode, the efficiency of methane increased with the addition of a small amount of Cu but the efficiency was lower than that on pure Cu electrode. Next, gas-diffusion electrodes have been employed as the cathode. The gas-diffusion electrodes have been prepared from sputter-deposited Cu-Ag alloyed powder, carbon black powder and polytetrafluoroethylene dispersion. Thegas-diffusion electrode only made up of carbon black powder produced exclusively hydrogen gas. However, the Cu-Ag alloy powder-loaded gas-diffusion electrodes produced methane and ethylene and the total reduction current density was remarkably high, but their faradaic efficiencies were lower than those on the plate-type alloyelectrodes.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), TOHOKU UNIVERSITY, 09650778
  • 耐高温腐食性非平衡合金の創製と耐食機構の解明
    科学研究費助成事業
    1997 - 1998
    幅崎 浩樹
    スパッタ法を用いてアモルファスAl-Nb-Mo三元合金を石英基板上に作製し,その高温硫化および酸化環境における耐食性を評価するとともに,その耐食機構について検討した.まず,Al-Nb-Mo合金の高温硫化は二段階の放物線則に従う硫化挙動を示し,保護性の硫化物スケールが生成し,その中の拡散が律速となることがわかった.定常状態における硫化速度は初期よりも小さく,より保護性の高いスケールが定常状態では生成している.その定常状態の硫化速度はニオブやモリブデン単体よりも小さく,さらにAl-MoやAl-Nb二元合金よりも小さいことが明らかとなった.また,その硫化速度はアルミニウム量がほぼ同じ場合,モリブデンよりもニオブの割合が多いほうが小さくなることも判明した.生成した硫化物スケールの解析を行ったところ,3層からなるスケールが生成していることがわかった.最外層にはAl_2S_3があり,その下に少量のアルミニウムを含むNbS_2,そして最内層は少量のアルミニウムを含んだMoS_2とNb_3S_4からなる.初期の比較的速い硫化はアルミニウムが優先的に硫化し,より保護性の高い高融点金属の硫化物が生成する前にAl_2S_3スケールが生成し,この中の拡散が反応を律速するためである.Nb-Mo二元合金を硫化した場合もNbS_2MoS_2-Nb_3S_4の2層スケールが形成したが,この合金よりもAl-Nb-Mo三元合金の方が高い耐高温硫化性を示したことから,Al^<3+>イオンがドープされたNbS_2/MoS_2-Nb_3S_4スケールはAl^<3+>イオンを含まない同じスケールよりも保護性が高いことが明らかとなった.Al-Nb-Mo三元合金の耐高温酸化性は合金中のアルミニウム量が多くなるほど向上し,直線則から放物線則に従う酸化挙動に変化した.放物線則を示した合金ではスケール表面に保護性の高いAl_2O_3層が生成することで耐酸化性が向上し,Al-21Nb-14Mo合金ではクロミアスケールを生成する耐熱合金に匹敵する耐高温酸化性を示すした.
    日本学術振興会, 奨励研究(A), 東北大学, 09750769
  • Tailoring of new amorphous alloy catalysts for conservation of atmosphere
    Grants-in-Aid for Scientific Research
    1995 - 1998
    HASHIMOTO Koji, AKIYAMA Eiji, HABAZAKI Hiroki, KAWASHIMA Asahi, ASAMI Katsuhiko
    Since non-equilibrium alloys become a single phase supersaturated solid solution by additions of large amounts of various elements, tailoring of catalysts for conservation of environments by combination of elements necessary for high reactivity and selectivity was aimed.
    1. Catalysts for decomposition of nitrogen oxides : For direct decomposition of nitrogen oxide to nitrogen and oxygen, Pd/NiTaO_6 catalyst formed from amorphous Ni-Ta-Pd alloys showed the most stable high reactivity in a wide temperature range up to 900ﾟC.When this was used as a catalyst for reduction of nitrogen monoxide by propane in oxygen containing atmosphere, a high conversion was observed at low temperatures such as 300ﾟC
    2. Catalysts for decomposition of chlorofluorocarbon : Amorphous Ni-Zr alloys possess high reactivity and durability for hydrolytic decomposition of CFC-12 into CO_2, HC1 and HF.The durability increased remarkably by the addition of phosphorus. Active species formed from the alloys were ZrF2, (F,O)_<2,706> and Zr(F,O)_<3.80ﾟ>
    3. Catalysts for methanation of carbon dioxide : Amorphous Ni-Zr alloys have the highest activity and 100% selectivity for methane formation by the reaction of CO_2 with H_2 in comparison with conventional Ni-impregnated ZrO_2, crystalline Ni-Zr and precious metal catalysts. Because nickel supported on tetragonal ZrO_2, which is an essentially metastable phase and formed during the reaction, showed a selectively high activity and because the addition of rare earth elements stabilizes the tetragonal ZrO_2 phase, the most active catalysts were obtained from amorphous Ni-Zr-rare earth element alloys.
    4. Hydrogen evolution cathodes for seawater electrolysis : Tailoring of highly active electrodes for production of hydrogen necessary for methanation of CO_2 was carried out by preparing amorphous alloys. Modification of the electronic structure of nickel by the addition of molybdenum resulted in the cathodes whose activities are competitive to that of platinum.
    Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), TOHOKU UNIVERSITY, 07405032
  • Tairoring Amorphous Surface Alloys Resistant against High Temperature Corrosion
    Grants-in-Aid for Scientific Research
    1993 - 1995
    HASHIMOTO Koji, KUMAGAI Naokazu, YOSHIOKA Hideaki, HABAZAKI Hiroki, KAWASHIMA Asahi, ASAMI Katsuhiko
    One of the objectives of this work is to tailor amorphous surface alloys on conventional metals by sputter deposition in order to protect the underlying conventional metals against sulfidation and oxidation at high temperatures. Tailoring active catalysis from amorphous alloy precursors for hydrolytic decomposition of cholorofluorocarbon is another aim of this work. We succeeded to prepare amorphous Al-Mo, Al-Nb and Al-Ta alloys with high resistance against both sulfidation and oxidation. In addition, the above-mentioned alloys with small additions of silicon have been obtained for further enhancement of oxidation resisitance. It is the first time on the history of corrosion science that the alloys with low sulfidation rates which are comparable to the oxidation rates of oxidation-resistant conventional alloys are obtained. Sulfide scales formed on these alloys consist of an outer aluminum sulfide layr and an inner refractory metal sulfide layr, the latter of which has high protectiveness against sulfidation. The amorphous alloys are converted to intermetallics at high temperatures where sulfidation and oxidation take place, but the formation of fine grained intermatallics is responsible for better adhesion of the alloys to the substrate metals. Silicone contained in the alloys form silicides with refractory elements in the alloys at high temperatures, and because the silicides are stable against oxidation, the presence of silicon suppresses oxidation of refractory elements. Amorphous surface alloys have been successfully prepared on 304 stainless steel and show high protectiveness against both sulfidation and oxidation at high temperatures.
    In the catalytic decomposition of a cholorofluorocarbon CCl_2F_2 by hydrolysis into CO_2, HCl and HF the catalyst should be exposed to very aggressive decomposition products. The active and durable catalysts have been obtained as a result of the catalystic reaction from amorphous Ni-Zr alloy precursors containing small amounts of chromium, molybdenum or tungsten.
    Japan Society for the Promotion of Science, Grant-in-Aid for Developmental Scientific Research (B), Institute for Materials Research, Tohoku University, 05555187
  • HOT SULFIDATION-AND OXIDATION-RESISTANT NEW ALLOYS
    Grants-in-Aid for Scientific Research
    1993 - 1994
    HASHIMOTO Koji, J-CZACHOR M., MROWEC S., AKIYAMA Eiji, KAWASHIMA Asahi, ASAMI Katsuhiko
    High temperature corrosion of sputter-deposited amorphous Al- (34-46) Mo and Al-31Mo- (6-16) Si alloys has been studies as a function of temperature in sulfur vapor, as well as in oxygen and air. The sulfidation process follows parabolic kinetics. The alloys showed excellent resistance to sulfide corrosion, their sulfidation rates being comparable with oxidation rates of chromia-forming materials. The oxidation resistance of binary Al-Mo alloys has been found to be satisfactory, but only at temperatures not exceeding 1073K.Above the melting point of MoO_3 (1069K), the scale, consisting mainly of Al_2O_3 with 5% MoO_3, becomes unprotectable because of evaporation of MoO_3. However, ternary Al-Mo-Si alloys show excellent resistance to oxidizing environment up to about 1200K,their oxidation rates being comparable with those of Al_2O_3 formers. This resulted from the fact that during heating of the ternary alloys, Mo_5Si_3 scale was formed instead of AlMo_3 formed.
    The beneficial effect of alloying with aluminum enhancing the sulfidation resistance of molybdenum has been studied as a function of aluminum content. The reaction rate of Mo-Al alloys with low aluminum contents is lower than that of pure molybdenum and decreases with increasing aluminum content. The lower sulfidation rate is explained in terms of the aluminum doping effect in the MoS_2 scale.
    Sputter-deposited Al-Nb alloys have excellent sulfidation resistance, their sulfidation rates being lower than that of niobium. Although their initial sulfidation rate is high due to the preferential sulfidation of aluminum, which leads to the enrichment of niobium at metal/scale interface, and consequently, the protective NbS_2 scale formed on the Al-Nb alloys.
    The resistance of these alloys to high temperature oxidation is higher than that of niobium. The oxide scale is composed of a double aluminum-niobium oxide and alumina, which lead to high oxidation resistance.
    Japan Society for the Promotion of Science, Grant-in-Aid for international Scientific Research, TOHOKU UNIVERSITY, 05044075
  • IN-SITU CHARACTERIZATION OF SURFACES ON NEW ELECTRODE FOR FUEL CELLS AND ELECTROLYSIS
    Grants-in-Aid for Scientific Research
    1991 - 1994
    HASHIMOTO Koji, AKIYAMA Eiji, HABAZAKI Hiroki, KAWASHIMA Asahi, ASAMI Katsuhiko
    X-ray photoelectron spectroscopy is an effective method for nondestructive determination of valence and composition in the specimen surface. In-situ determination of the surface is particularly necessary for a better understanding of chemical species contributing to the reaction on the electrode surface exposed to relatively low oxidizing power. In-situ characterization in XPS is to determine the surface without oxidation of the surface species as a result of exposure to air before being exposed to high vacuum of the X-ray photoelectron spectrometer.
    In the present work an electrode in an electrolytic cell is rinsed with deaerated distillled water, transferred without air exposure into a globe box and is mounted on an air-tight transfer vessel for X-ray photoelectron spectrometer under nitrogen atmosphere in the globe box. Useful information has been obtained for the electrode surface without the detrimental effect of air oxidation.
    These include fuel cell electrodes for hydrogen, methane, ethane and propane as fuels, electrodes for evolution of hydrogen, chlorine and oxygen in electrolysis of seawater and electrodes for electrochemical oxidation of sulfite. In the study of amorphous alloy electrodes for fuel cells additions of platinum group elements and tin are effective in enhancing the electrocatalytic activity. The presence of a redox system of Sn^<2+>/Sn^<4+> which accelerates oxidation of fuels is confirmed. When the electrode is exposed to air after electrolysis, even platinum group elements are readily covered with oxides and hence the specification of the effective species for the electrode reactions is difficult. In fact platinum group elements directly act in the metallic state for oxidation of fuels and sulfite. These could not be obtained so far by ex-situ surface characterization.
    Japan Society for the Promotion of Science, Grant-in-Aid for General Scientific Research (A), INSTITUTE FOR MATERIALS RESEARCH,TOHOKU UNIVERSITY, 03403012
  • 耐高温酸化性と耐高温硫化性を兼ね備えたアモルファスアルミニウム合金の耐食機構
    科学研究費助成事業
    1993 - 1993
    幅崎 浩樹, 秋山 英二
    耐高温硫化性と耐高温酸化性を兼ね備えた材料を見出すことを目的として,スパッター法によりアモルファスアルミニウム-高融点合金を作製し,その耐高温硫化性を10^3Paの硫黄蒸気中,耐高温酸化性を空気中で調べた。アモルファスAl-Mo合金の硫化は,放物線則に従い,その耐高温硫化性は金属モリブデンよりも高く,これまで知られている金属材料の中でも最も高いことがわかった。生成したスケールは二層からなり,外層はAl_2S_3,内層はMoS_2が主体であった。また,スケールは硫黄の内方拡散により成長することがマーカー試験により明らかになった。このアモルファスAl-Mo合金が高い耐高温硫化性を示す理由は,内層の主体であるMoS_2へのアルミニウムのドーピング効果によると考えられる。実際,モリブデンへ少量のアルミニウムを添加した場合,その添加量に応じて硫化速度が低下することからも,このことは支持された。
    Al-Mo合金の高温酸化速度は,1123Kまでは,クロミアスケールを形成する合金に匹敵するが,それ以上の温度では,酸化モリブデンの蒸発のため,重量減少が起こり,耐酸化性は充分ではない。このAl-Mo合金にケイ素を添加すると,耐酸化性は1223Kまで典型的なアルミナスケールを形成する合金に匹敵するほどまで向上した。ただし,過剰のケイ素の添加は耐高温硫化性を低下させた。ケイ素の添加のより耐酸化性が向上するのは,Al-Mo二元合金の場合には,高温でAl_8Mo_3とAlMo_3が生成するのに対し,ケイ素を添加した合金ではモリブデンリッチの金属間化合物に代わって,シリコンリッチで,耐酸化性に優れたMo_5Si_3が生成することが最も大きな要因であり,これによりモリブデンの酸化が抑制されたと考えられる。Al-Nb合金は耐酸化性は低いものの,耐高温硫化性はニオブを上回ることがわかった。
    日本学術振興会, 一般研究(C), 東北大学, 05650698
  • 機能性材料表面の創製　　　　　　　　　　　　　　　
    Competitive research funding
  • Tailoring of novel materials with surface functions　　　　　　　　　　　　　　　
    Competitive research funding

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syllabus

  • エネルギー材料特論, 2024年, 修士課程, 総合化学院
  • 物理化学Ⅰ, 2024年, 学士課程, 工学部
  • 電気化学, 2024年, 学士課程, 工学部