Updated on 2026/04/22

写真a

 
TOKUNAGA DAIJIRO
 
Organization
School of Engineering Assistant Professor
Title
Assistant Professor
External link

Research Interests

  • マランゴニ対流

  • 積層造形

  • レーザ溶接

  • 内部加工

  • ガラス

  • ダイヤモンド

  • セラミックス

  • レーザ

  • デンドライト結晶

  • 気泡

  • 可視化

Research Areas

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Manufacturing and production engineering

Education

  • Chiba University

    2020.4 - 2023.3

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    Country: Japan

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  • Chiba University

    2018.4 - 2020.3

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  • Chiba University   Faculty of Engineering   Mechanical Engineering

    2014.4 - 2018.3

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    Country: Japan

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Research History

  • Institute of Science Tokyo   School of Engineering, Department of Mechanical Engineering   Assistant Professor

    2023.4

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    Country:Japan

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Professional Memberships

Papers

  • Near-infrared in situ observation of bubble migration and crystal growth behavior in a laser-induced Al2O3 molten pool

    Daijiro Tokunaga, Yuko Aono, Atsushi Hirata

    Journal of Visualization   2025.10

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    Authorship:Lead author   Publishing type:Research paper (scientific journal)  

    DOI: 10.1007/s12650-025-01087-0

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  • Laser-Induced Two-Way Shape Memory Effect in TiNiCu Films of Different Thicknesses

    Chihiro Nara, Takahiro Kurosawa, Daijiro Tokunaga, Atsushi Hirata, Junpei Sakurai, Yuko Aono

    Nanomanufacturing and Metrology   8 ( 1 )   2025.7

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    Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    Abstract

    Shape memory alloys (SMAs) can recover their original shape after deformation when heated above a specific transformation temperature. This study investigates the induction of the two-way shape memory effect (TWSME) in SMA films through laser surface treatment. Ti50Ni40Cu10 SMA films with thicknesses of 20–40 μm were fabricated using the melt-spinning method and subjected to laser irradiation under varying conditions. The effects of film thickness and laser parameters on actuation characteristics and crystalline structure were evaluated. The results demonstrate the successful induction of TWSME in the laser-treated SMA films, with actuation capability depending on the balance between the modified and unmodified layers through the thickness. X-ray diffraction analysis reveals the presence of residual martensitic phase in the laser-treated specimens, contributing to the TWSME. Optimal actuation is achieved with a relatively thick modified layer while maintaining sufficient unmodified material for recovery to the memorized shape. This study provides insights into the laser-induced TWSME in SMA films and its potential applications in microactuators, where bidirectional actuation without external preloading is desirable.

    DOI: 10.1007/s41871-025-00263-y

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    Other Link: https://link.springer.com/article/10.1007/s41871-025-00263-y/fulltext.html

  • Fundamental study on direct and serial joining of spherical alumina particles with CO2 laser Reviewed

    Yuta Hosoya, Daijiro Tokunaga, Satoshi Momozono, Yuko Aono, Atsushi Hirata

    Journal of Materials Processing Technology   326   118314 - 118314   2024.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.jmatprotec.2024.118314

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  • Laser slicing of a diamond at the {100} plane using an irradiation sequence that restricts crack propagation along the {111} plane Reviewed

    Kosuke Sakamoto, Daijiro Tokunaga, Sho Itoh, Hirofumi Hidai, Souta Matsusaka, Takashige Omatsu, Koji Koyama, Seong-Woo Kim, Noboru Morita

    Diamond and Related Materials   110045 - 110045   2023.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.diamond.2023.110045

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  • Curved hole drilling by laser manipulation of a heat spot inside glass Reviewed

    Kaito Miyakoda, Koki Sunayama, Kosuke Sakamoto, Daijiro Tokunaga, Hirofumi Hidai, Souta Matsusaka

    Precision Engineering   81   1 - 7   2023.5

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.precisioneng.2023.01.008

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  • Slicing of diamond by internal modification with ultrashort pulsed laser illumination Reviewed

    徳永大二郎, 佐藤正隆, 伊東翔, 比田井洋史, 比田井洋史, 尾松孝茂, 尾松孝茂, 松坂壮太

    砥粒加工学会誌   67 ( 6 )   2023

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    Authorship:Lead author   Language:Japanese  

    J-GLOBAL

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  • Focus movement distance per pulse dependence of electrical conductivity and diameter of diamond internal modification induced by picosecond laser Reviewed

    Daijiro Tokunaga, Masataka Sato, Sho Itoh, Hirofumi Hidai, Takashige Omatsu, Souta Matsusaka

    Scientific Reports   12 ( 1 )   2022.10

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    Abstract

    Internal and local modifications via ultrashort pulsed laser illumination to diamond are promising for manufacturing diamond electronic devices. The relationship between the diameter/electrical conductivity of modified regions and the laser fluence distribution was investigated. Picosecond laser illumination without scanning the laser focus fabricated short modified regions in diamond. As a result, the calculated laser fluence distribution matches the distribution of the modified regions. Wire-shaped modified regions were fabricated via laser illumination with scanning of the laser focus, and the corresponding diameter and electrical conductivity were investigated by controlling the laser focus movement distance per pulse (Vf). The modified regions fabricated with varying Vf were divided into three categories depending on the trend of the relationship between the diameter and electrical conductivity. The diameters of the modified regions were constant at the maximum values when Vf was sufficiently small, decreased with increasing Vf, and reached a minimum when Vf was sufficiently large. The modified regions became more electrically conductive with increasing Vf, even when the deposited energy per unit length decreased. Moreover, the electrical conductivity decreased significantly when the diameter became constant at the minimum value. Finally, the relationship between the diameter/electrical conductivity of the modified regions and the laser fluence distribution was elucidated.

    DOI: 10.1038/s41598-022-21432-9

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    Other Link: https://www.nature.com/articles/s41598-022-21432-9

  • Branched hole drilling in silica glass by continuous-wave laser backside irradiation Reviewed

    Shun Sato, Daijiro Tokunaga, Hirofumi Hidai, Souta Matsusaka, Akira Chiba, Noboru Morita

    Precision Engineering   60   189 - 193   2019.11

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Elsevier BV  

    DOI: 10.1016/j.precisioneng.2019.07.021

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  • A novel method of triggering fiber fuse inside glass by optical breakdown and glass drilling as its application Reviewed

    Daijiro Tokunaga, Shun Sato, Hirofumi Hidai, Souta Matsusaka, Akira Chiba, Noboru Morita

    Applied Physics A   125 ( 6 )   2019.5

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    Authorship:Lead author   Language:English   Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    DOI: 10.1007/s00339-019-2691-9

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    Other Link: http://link.springer.com/article/10.1007/s00339-019-2691-9/fulltext.html

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MISC

  • 超短パルスレーザによる ダイヤモンドの スライシング

    徳永 大二郎, 坂本 康輔, 佐藤 正隆, 比田井 洋史, 松坂 壮太

    New diamond = ニューダイヤモンド / ニューダイヤモンドフォーラム   40 ( 4 )   10 - 13   2024.10

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    Authorship:Lead author   Language:Japanese   Publishing type:Article, review, commentary, editorial, etc. (scientific journal)  

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  • 「超短パルスレーザ誘起内部変質によるダイヤモンドスライス加工」こぼれ話 Invited

    徳永大二郎

    砥粒加工学会誌   68 ( 7 )   363 - 364   2024.7

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    Authorship:Lead author   Language:Japanese  

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  • ダイヤモンドのレーザ加工

    光技術動向調査報告書   2023.3

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    Authorship:Lead author  

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Presentations

  • Analysis of bubble motion in molten alumina induced by laser irradiation using particle tracking velocimetry (PTV) International conference

    Daijiro Tokunaga, Yuko Aono, Atsushi Hirata

    21th International Symposium on Flow Visualization  2025.6 

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    Event date: 2025.6

    Language:English   Presentation type:Oral presentation (general)  

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  • レーザ照射雰囲気がAl2O3の溶融凝固挙動に与える影響

    渡邊貴博, 徳永大二郎, 青野祐子, 平田敦

    2025年度精密工学会春季大会学術講演会  2025.3 

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    Event date: 2025.3

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  • 近赤外光を利用したレーザ溶融アルミナの高倍率in-situ観察

    徳永大二郎, 青野祐子, 平田敦

    2025年度精密工学会春季大会学術講演会  2025.3 

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    Event date: 2025.3

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  • 炭化タングステンへの高温レーザピーニングによる特性向上

    青野 祐子, 徳永 大二郎, 平田 敦

    日本機械学会第31 回機械材料・材料加工技術講演会(M&P2024) 2024年11月3日  2024.11 

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    Event date: 2024.11

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  • PPG-MPU系形状記憶ポリマーの熱成形とその機械特性評価

    兪 智善, 徳永 大二郎, 平田 敦, 青野 祐子

    日本機械学会第31 回機械材料・材料加工技術講演会(M&P2024)  2024.11 

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    Event date: 2024.11

    Language:Japanese   Presentation type:Poster presentation  

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  • 薄膜形状記憶合金へのレーザ表面処理による駆動特性改質効果

    奈良 千尋, 徳永 大二郎, 平田, 敦, 櫻井 淳平, 青野 祐子

    日本機械学会第31 回機械材料・材料加工技術講演会(M&P2024)  2024.11 

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    Event date: 2024.11

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  • Laser Treatment Induced Two-Way Shape Memory Effect on different thickness TiNiCu films International conference

    Chihiro Nara, Takahiro Kurosawa, Daijiro Tokunaga, Atsushi Hirata, Jumpei Sakurai, Yuko Aono

    The 20th International Conference on Precision Engineering  2024.10 

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    Event date: 2024.10

    Language:English   Presentation type:Poster presentation  

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  • Direct observation of bubbles inside the molten pool in laser welding of Alumina International conference

    Daijiro Tokunaga, Yuko Aono, Atsushi Hirata

    The 20th International Conference on Precision Engineering  2024.10 

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    Event date: 2024.10

    Language:English   Presentation type:Oral presentation (general)  

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  • 近赤外光を利用したレーザ溶融セラミックス内気泡の可視化

    徳永 大二郎, 青野 祐子, 平田 敦

    2024年度精密工学会秋季大会学術講演会  2024.9 

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    Event date: 2024.9

    Language:Japanese   Presentation type:Oral presentation (general)  

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  • 熱履歴制御によるセラミックス微小要素の高強度レーザ融接の試み

    徳永大二郎, 渡辺貴博, 青野裕子, 平田敦

    2024年度精密工学会春季大会学術講演会  2024.3 

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    Event date: 2024.3

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  • 大電力パルスマグネトロンスパッタリングSiC薄膜のレーザ改質による潤滑性の向上

    佐藤智輝, 稲葉梨々花, 徳永大二郎, 青野裕子, 平田敦

    2024年度精密工学会春季大会学術講演会  2024.3 

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    Event date: 2024.3

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  • Crack propagation direction in diamond by laser illumination International conference

    Kosuke Sakamoto, Daijiro Tokunaga, Hirofumi Hidai, Sho Itoh, Takashige Omatsu, Koji Koyama, Seong-woo Kim, Souta Matsusaka

    The 25th International Symposium on Advance in Abrasive Technology  2023.12 

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    Event date: 2023.12

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  • ピコ秒レーザ光を用いたダイヤモンド内部の亀裂進展

    坂本 康輔, 徳永 大二郎, 比田井 洋史, 伊東 翔, 尾松 考茂, 小山 浩司, 金 聖祐, 松坂 壮太

    2023年度精密工学会秋季大会学術講演会  2023.9 

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    Event date: 2023.9

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  • ピコ秒パルスレーザ光を用いた{100}面でのダイヤモンドレーザスライシング

    坂本 康輔, 徳永 大二郎, 比田井 洋史, 伊東 翔, 尾松 考茂, 小山 浩司, 金 聖祐, 松坂 壮太

    ABTEC 2023  2023.8 

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    Event date: 2023.8

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  • Observation of crack propagation and stress distribution in diamond induced by ultrashort-pulsed laser illumination International conference

    D. Tokunaga, K. Sakamoto, S. Itoh, H. Hidai, T. Omatsu, S. Matsusaka

    Proc. SPIE 12409, Laser-based Micro and Nanoprocessing XVII  2023.1 

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    Event date: 2023.1 - 2023.2

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  • Shape of the ultrashort-pulsed laser-modified region in diamonds International conference

    Daijiro Tokunaga, Hirofumi Hidai, Souta Matsusaka, Akira Chiba, Takashige Omatsu, Noboru Morita

    The 23rd International Symposium on Advances in Abrasive Technology  2021.12 

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    Event date: 2021.11 - 2021.12

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  • レーザにより生成されるダイヤモンド内部変質詳細観察およびスライス加工への応用

    徳永 大二郎, 比田井 洋史, 松坂 壮太, 千葉 明, 尾松 孝茂, 森田 昇

    2021年度精密工学会春季大会学術講演会 

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    Event date: 2021.3

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  • Blanched hole drilling in glass by two beam illumination International conference

    Daijiro Tokunaga, Shun Sato, Hirofumi Hidai, Souta Matsusaka, Akira Chiba, Noboru, Morita

    The 8th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN 2019)  2019.11 

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    Event date: 2019.11

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  • レーザによるダイヤモンド内部黒鉛に対する通電加熱および抵抗値の温度依存性計測

    徳永大二郎, 比田井洋史, 松坂壮太, 千葉明, 森田昇

    2019年度砥粒加工学会学術講演会  2019.8 

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    Event date: 2019.8

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  • A novel method of triggering fiber fuse inside glass by breakdown International conference

    Daijiro Tokunaga, Shun Sato, Hirofumi Hidai, Souta Matsusaka, Akira Chiba, Noboru Morita

    2019 International Conference on Smart Science  2019.3 

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    Event date: 2019.3 - 2019.4

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  • 超短パルスレーザによるダイヤモンド内部加工

    徳永大二郎, 比田井洋史, 松坂壮太, 千葉明, 森田昇

    第25回「精密工学会 学生会員卒業研究発表講演会論文集」  2018.3 

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  • 超短パルスレーザ による単結晶ダイ ヤモンドウエハの スライシング加工 Invited

    徳永大二郎

    公益社団法人 精密工学会/公益財団法人 精密測定技術振興財団 共催 第440 回講習会  2024.11 

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    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  • Diamond slicing at the {100} plane using a picosecond laser beam by developed method restricting crack propagation along the cleaved plane International conference

    Kosuke Sakamoto, Daijiro Tokunaga, Hirofumi Hidai, Sho Itoh, Takashige Omatsu, Koji Koyama, Seong-Woo Kim, Souta Matsusaka

    Progress in Ultrafast Laser Modification of Materials  2023.6 

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    Language:English   Presentation type:Poster presentation  

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  • 単結晶ダイヤモンドのレーザスライシング Invited

    徳永大二郎

    公益社団法人砥粒加工学会 次世代固定砥粒加工プロセス専門委員会 第121回研究会  2025.6 

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    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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  • 半導体結晶材料のレーザ加工/スライシング技術 Invited

    一般社団法人 溶接学会 第143回 マイクロ接合研究委員会  2023.9 

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    Language:Japanese   Presentation type:Public lecture, seminar, tutorial, course, or other speech  

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Industrial property rights

  • Method for Slicing Crystal Material, Method for Manufacturing Wafer, and Member comprising Crystal Material

    Hirofumi Hidai, Kosuke Sakamoto, Daijiro Tokunaga, Souta Matsusaka, Sho Ito, Koji Koyama, Kim Seongwoo

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    Application no:特願PCT/JP2024/011511 

    Announcement no:特開2025-12322A 

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Awards

  • 2023年度 砥粒加工学会賞論文賞

    2023.3   公益社団法人砥粒加工学会   超短パルスレーザ誘起内部変質によるダイヤモンドスライス加工

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    Award type:Honored in official journal of a scientific society, scientific journal 

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  • YOUNG RESERCHERS AWORD

    2019.11   The Japan Society for Precision Engineering  

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    Award type:Award from international society, conference, symposium, etc. 

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  • 2025年度春季精密工学会学術講演会 アドバンスト・ベストプレゼンテーション賞

    2025.3   公益社団法人精密工学会  

    徳永大二郎,青野祐子,平田敦

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    Award type:Award from Japanese society, conference, symposium, etc. 

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  • ICPE2024 Poster Paper Award

    2024.11   The Japan Society for Precision Engineering  

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  • 2024年度秋季精密工学会学術講演会 ベストプレゼンテーション賞

    2024.9   公益社団法人精密工学会  

    徳永大二郎, 青野祐子, 平田敦

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    Award type:Award from Japanese society, conference, symposium, etc. 

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  • 全方位イノベーション創発博士人材養成プロジェクト 優秀賞

    2023.3   千葉大学  

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  • 千葉大学大学院融合理工学府長賞

    2020.3   千葉大学  

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  • 日本機械学会三浦賞

    2020.3   日本機械学会  

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Research Projects

  • セラミックス融液内気泡の近赤外光を用いたその場観察および複合場による制御の試み

    Grant number:25K17521  2025.4 - 2028.3

    日本学術振興会  科学研究費助成事業  若手研究

    徳永 大二郎

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    Grant amount:\4810000 ( Direct Cost: \3700000 、 Indirect Cost:\1110000 )

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  • マルチレーザ照射によるセラミックス微小要素の高効率レーザ融接の試み

    2024.10 - 2027.3

    公益財団法人天田財団  奨励研究助成(若手研究者枠) 

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    Authorship:Principal investigator 

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  • 最密充填粉末床の作製および高精度な熱履歴制御によるセラミックス溶融積層造形手法の開発

    2024.6 - 2026.6

    公益財団法人みずほ学術振興財団  「第67回 工学研究助成」 

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    Authorship:Principal investigator 

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  • 極限的時間・空間分解能での溶融金属の流動挙動と冷却過程のダイナミクス解明

    Grant number:23KK0068  2023.9 - 2028.3

    日本学術振興会  科学研究費助成事業  国際共同研究加速基金(海外連携研究)

    比田井 洋史, 松坂 壮太, 伊東 翔

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    Grant amount:\21060000 ( Direct Cost: \16200000 、 Indirect Cost:\4860000 )

    高温の溶融金属が流動しながら冷却し凝固するプロセスは鋳造,溶断,溶接など金属部品の製造工程で広範にみられる.その流動速度,冷却速度,凝固プロセスは結晶構造,機械的特性と密接に関係し,その性能を決める重要な要素である.これまでは流動速度や温度測定が困難であった.これに対して,本手法では溶融金属に近接し,極めて高い空間・時間分解能で流動速度や温度測定する手法を実現する.
    高温溶融金属が流動しながら冷却し凝固するプロセスは金属部品の製造工程で幅広く見られる.この際の流動速度と冷却速度は結晶構造を決定し,結晶構造は強度などの機械的特性を決定する重要な要素である.本申請では,溶融金属が流動しながら急冷,凝固する様子を高い時間・空間分解能で可視化し,流動速度と冷却速度の測定法を確立する.このために,国際共同研究先とともに開発したレーザフェムトキャストプロセスを活用する.これは石英ガラスを型として用い,形成した微小な空洞にレーザ加熱により溶融した金属を高圧ガスにより注入する方法である.さらに,流動速度,冷却速度が結晶状態,機械的特性にどのように影響を与えるか明らかにする.あわせて,金属とガラス型の界面反応についても理解を深め,利用できる金属の種類を詳らかにする.最終的に応用のデモンストレーションとして微細3次元構造物の作製までを目的とする.
    本年度は,実験プラットフォームの改良の準備を行った.型の温度を制御できるようにガラスに吸収されるCO2レーザ,COレーザによる加熱に対応できるように改良したプラットフォームを設計した.さらにEPFLで行う型の作製をより効率的にできるように,型全体の形状とプラットフォームを改良した.さらに,金属温度表面の温度計測,凝固後の金属の構造の評価を行った.これらの結果から,型の形状の改良を行った.

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  • セラミックス微小要素の高強度レーザ融接およびメカニズムの解明

    Grant number:23K19095  2023.8 - 2025.3

    日本学術振興会  科学研究費助成事業  研究活動スタート支援

    徳永 大二郎

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    Grant amount:\2860000 ( Direct Cost: \2200000 、 Indirect Cost:\660000 )

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  • 超短パルスレーザによるダイヤモンド内部黒鉛化現象を利用したスライス加工

    2020.7 - 2021.6

    公益財団法人工作機械技術振興財団  第41次試験研究助成 

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    Authorship:Principal investigator 

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Teaching Experience

  • 機械系発展実験

    2024.4 Institution:東京科学大学

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    Level:Undergraduate (specialized) 

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Media Coverage

  • Semiconductor Researchers Solve Diamond Wafer Slicing Challenges With Lasers Internet

    2023.8

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