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Go Yamamoto

Section

Graduate School of Engineering

Job title

Associate Professor

Degree

博士（学術）（東北大学）
修士（教育学）（福島大学）

researchmap

https://researchmap.jp/Go_Yamamoto

J-GLOBAL ID

201201079614600585

ORCID

https://orcid.org/0000-0001-7983-729X

Committee Memberships 15

Nanomaterials　Editorial Board Member

2020/07 - Present
International Journal of Mechanical Engineering and Applications　Editorial Board Member

2020/06 - Present
The 9th International Conference on Nanostructures, Nanomaterials and Nanoengineering 2020　Technical committee

2020/04 - Present
7th Asian Conference on Mechanics of Functional Materials and Structures　International Organizing Committee

2020 - Present
日本複合材料学会東北・北海道支部　支部監事

2017/04 - Present
日本複合材料学会東北・北海道支部　支部監事

2017/04 - Present
日本航空宇宙学会北部支部２０２２年講演会ならびに第３回再使用型宇宙輸送系シンポジウム　実行委員

2022/03 - 2022/03
日本機械学会第2９回機械材料・材料加工技術講演会（M&P2021）　実行委員

2021/11 - 2021/11
東北⼤学材料科学ウェビナー2021　運営委員

2021/09 - 2021/09
日本航空宇宙学会北部支部　幹事

2019 -
日本航空宇宙学会　編集委員

2019 -
The 5th Asian Symposium on Materials and Processing　Scientific and Program committee

2018 -
日本機械学会　材料力学部門シンポジウム実行委員会(M&M若手シンポジウム担当委員会) 実行委員

2018 -
日本複合材料学会　第42回複合材料シンポジウム実行委員

2017 -
日本機械学会　M&M2014材料力学カンファレンス実行委員

2014 -

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Professional Memberships 3

日本セラミックス協会
日本複合材料学会
日本機械学会

Research Interests 4

マルチスケールメカニクス
Nanomechanics
Composite materials
Fracture mechanics

Research Areas 1

Nanotechnology/Materials / Structural and functional materials / composite materials; nanomechanics; micromechanics; carbon nanomaterials; resonance ultrasound spectroscopy; high-throughput screening calculation

Awards 6

日本機械学会材料力学部門優秀講演表彰 (若手シンポジウム)

2013/03/29　日本機械学会
2010年度日本機械学会奨励賞(研究)

2011/04/21　日本機械学会
日本機械学会材料力学部門優秀講演表彰

2010/10/30　日本機械学会
第7回PM研究促進展奨励賞

2009/10　日本粉末冶金工業会
財団法人青葉工学振興会第14回研究奨励賞

2008/12　財団法人青葉工学振興会
東北大学環境科学研究科長賞

2006/03　東北大学

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Papers 114

Interfacial delamination between semicrystalline polymers and filler materials by coarse-grained molecular dynamics simulations Peer-reviewed

Yuji Higuchi, Yuta Hikima, Naoto Kamiuchi, Erica Uehara, Yutaka Oya, Go Yamamoto, Keita Sakakibara

Polymer　333　128539-128539　2025/08
Publisher: Elsevier BV
DOI： 10.1016/j.polymer.2025.128539 　

ISSN： 0032-3861
Enhanced interfacial strength in carbon-nanotubes-reinforced Al matrix composites via an interface substitution strategy Peer-reviewed

Weiwei Zhou, Zhenxing Zhou, Mingqi Dong, Yuchi Fan, Keiichi Shirasu, Go Yamamoto, Naoyuki Nomura

Composites Part A: Applied Science and Manufacturing　195　108955-108955　2025/08
Publisher: Elsevier BV
DOI： 10.1016/j.compositesa.2025.108955 　

ISSN： 1359-835X
Unravelling the role of inter CNT yarn–yarn interactions in governing the failure behavior in a unidirectional CNT yarn-reinforced plastic composite Peer-reviewed

Go Yamamoto, Sojun Nakano, Haruki Oyamada, Redha Akbar Ramadhan, Shugo Okamoto, Akihisa Takeuchi, Masayuki Uesugi, Akira Kunitomo, Nozomu Shigemitsu, Takuma Abe, Yoshinobu Shimamura, Haruto Kurono, Sota Goto, Yoku Inoue, Yasuhiko Hayashi, Hiroyuki Kawada

Composites Science and Technology　111137-111137　2025/03
Publisher: Elsevier BV
DOI： 10.1016/j.compscitech.2025.111137 　

ISSN： 0266-3538
Determination of elastic constants in complex-shaped materials through vibration-mode-pattern-matching-assisted resonant ultrasound spectroscopy Peer-reviewed

Go Yamamoto, Yuto Sakuda

Journal of Applied Physics　2024/05

DOI： 10.1063/5.0185423 　
Tensile strength prediction of unidirectional polyacrylonitrile (PAN)-based carbon fiber reinforced plastic composites considering stress distribution around fiber break points Peer-reviewed

Go Yamamoto, Kenta Oshima, Redha Akbar Ramadhan, TaeGyeong Lim, Yonas Tsegaye Megra, Ji Won Suk, Jun Watanabe, Haruki Okuda, Fumihiko Tanaka

Composites Part A　183　(108234)　2024/04

DOI： 10.1016/j.compositesa.2024.108234 　
Design of high mechanical performance carbon nanotube structure: machine-learning assisted high-throughput molecular dynamics simulation approach Peer-reviewed

Go Yamamoto, Xi Xiang, Koji Shimoyama, Keiichi Shirasu

Proceedings of ICCM International Conferences on Composite Materials (2023)　2024/01
Decreasing vacancy-defect sensitivity in multi-walled carbon nanotubes through interwall coupling Peer-reviewed

Go Yamamoto, Yu Chen, Akira Kunitomo, Nozomu Shigemitsu, Tatsunori Shindo

Carbon Trends　11　100266-100266　2023/06
Publisher: Elsevier BV
DOI： 10.1016/j.cartre.2023.100266 　

ISSN： 2667-0569
Determination of transverse isotropic elastic constants of nacre and constituent tablets based on genetic-algorithm-assisted resonant ultrasound spectroscopy Peer-reviewed

Go Yamamoto, Kazuma Matsui, Shuma Yuki, Ji Won Suk

Results in Materials　in press　2022/08
Study on the mechanical and electrical properties of twisted CNT yarns fabricated from CNTs with various diameters Peer-reviewed

Yoku Inoue, Kohei Hayashi, Motoyuki Karita, Takayuki Nakano, Yoshinobu Shimamura, Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

Carbon　176　400-40　2021/05

DOI： 10.1016/j.carbon.2021.01.139 　

ISSN： 0008-6223
Molecular dynamics simulations and theoretical model for engineering tensile properties of single‐and multi‐walled carbon nanotubes Peer-reviewed

Keiichi Shirasu, Shunsuke Kitayama, Fan Liu, Go Yamamoto, Toshiyuki Hashida

Nanomaterials　11　(3)　1-11　2021/03
Publisher: MDPI AG
DOI： 10.3390/nano11030795 　

eISSN： 2079-4991

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To apply carbon nanotubes (CNTs) as reinforcing agents in next-generation composites, it is essential to improve their nominal strength. However, since it is difficult to completely remove the defects, the synthesis guideline for improving nominal strength is still unclear, i.e., the effective strength and the number of nanotube layers required to improve the nominal strength has been undermined. In this study, molecular dynamics simulations were used to elucidate the effects of vacancies on the mechanical properties of CNTs. Additionally, the relationships between the number of layers and effective and nominal strengths of CNTs were discussed theoretically. The presence of extensive vacancies provides a possible explanation for the low nominal strengths obtained in previous experimental measurements of CNTs. This study indicates that the nominal strength can be increased from the experimentally obtained values of 10 GPa to approximately 20 GPa by using six to nine nanotube layers, even if the increase in effective strength of each layer is small. This has advantages over double-walled CNTs, because the effective strength of such CNTs must be approximately 60 GPa to achieve a nominal strength of 20 GPa.
A data mining approach to investigate the carbon nanotubes mechanical properties via high-throughput molecular simulation

Yi Xiang, Go Yamamoto

Materials Science Forum　1023　29-36　2021
Publisher: Trans Tech Publications Ltd
DOI： 10.4028/www.scientific.net/MSF.1023.29 　

ISSN： 1662-9752 0255-5476
Tensile-strength-controlling factors in unidirectional carbon fiber reinforced plastic composites Peer-reviewed

Go Yamamoto, Keita Koizumi, Takahiro Nakamura, Noriyuki Hirano, Tomonaga Okabe

Composites Part A: Applied Science and Manufacturing　140　106140-106140　2021/01

DOI： 10.1016/j.compositesa.2020.106140 　

ISSN： 1359-835X

eISSN： 1878-5840
Machine learning-assisted high-throughput molecular dynamics simulation of high-mechanical performance carbon nanotube structure Peer-reviewed

Yi Xiang, Koji Shimoyama, Keiichi Shirasu, Go Yamamoto

Nanomaterials　10　(12)　2459-13　2020/12/09

DOI： 10.3390/nano10122459 　

eISSN： 2079-4991
Enhanced tribological performance of alumina composites reinforced with acid-treated carbon nanotubes under water lubrication Peer-reviewed

Keiichi Shirasu, Takuto Miyaura, Go Yamamoto, Takaharu Suzuki, Kimiyoshi Naito, Toshiyuki Hashida

Diamond and Related Materials　101　2020/01

DOI： 10.1016/j.diamond.2019.107657 　

ISSN： 0925-9635
Stack-coating of multishell carbon layers templated with carbon nanotube Peer-reviewed

Materials Today Communications　21　100608　2019/08
Considering the stress concentration of fiber surfaces in the prediction of the tensile strength of unidirectional carbon fiber-reinforced plastic composites Peer-reviewed

Go Yamamoto, Miho Onodera, Keita Koizumi, Jun Watanabe, Haruki Okuda, Fumihiko Tanaka, Tomonaga Okabe

Composites Part A: Applied Science and Manufacturing　121　499-509　2019/06

DOI： 10.1016/j.compositesa.2019.04.011 　

ISSN： 1359-835X

eISSN： 1878-5840
How do the mechanical properties of carbon nanotubes increase? An experimental evaluation and modeling of the engineering tensile strength of individual carbon nanotubes Peer-reviewed

Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

Materials Research Express　6　(5)　055047　2019/05
Numerical study for tensile strength prediction of unidirectional carbon fiber-reinforced composite considering fiber surface stress concentration

Go Yamamoto, Tomonaga Okabe

MECHANICAL ENGINEERING JOURNAL　6　(3)　2019

DOI： 10.1299/mej.19-00020 　

ISSN： 2187-9745
Effects of high-temperature thermal annealing on properties of aligned multi-walled carbon nanotube sheets and their composites Peer-reviewed

Tran Huu Nam, Ken Goto, Yoshinobu Shimamura, Yoku Inoue, Go Yamamoto, Keiichi Shirasu, Toshiyuki Hashida

Composite Interfaces　2019
Mechanical and thermal expansion properties of aligned carbon nanotube reinforced epoxy composites Peer-reviewed

Keiichi Shirasu, Itaru Tamaki, Go Yamamoto, Toshiyuki Hashida

Mechanical Engineering Journal　2019
Investigating nanostructures in carbon fibres using Raman spectroscopy Peer-reviewed

Haruki Okuda, Robert J. Young, Daniel Wolverson, Fumihiko Tanaka, Go Yamamoto, Tomonaga Okabe

Carbon　130　178-184　2018/04/01
Publisher: Elsevier Ltd
DOI： 10.1016/j.carbon.2017.12.108 　

ISSN： 0008-6223
Effect of graphitization on mechanical properties of untwisted carbon nanotube yarn and its strength development mechanism Peer-reviewed

KIM Taesung, HAYASHI Anri, NIKAWA Hidefumi, SHIRASU Keiichi, YAMAMOTO Go, HASHIDA Toshiyuki, HOSOI Atsushi, KAWADA Hiroyuki

Transactions of the JSME (in Japanese)　84　(860)　17-00585-17-00585　2018/03
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/transjsme.17-00585 　

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<p>Carbon nanotube yarn, which is an aggregation of Carbon nanotubes (CNTs), enables CNTs to be used on macro scale. However, tensile strength of the CNT yarn is much lower than CNT itself, and improvement of the mechanical properties is a challenge for practical application of the yarns. CNTs composing the yarns include some defect structures and impure materials, and their presence can cause a decrease in tensile strength of the yarn. In this study, untwisted CNT yarns were fabricated by dry spun method and graphitized at a temperature of 2800°C for the purpose of improving mechanical properties. Additionally, strength of a CNT composing the yarn and interactive force between the CNTs were evaluated to clarify strength development mechanism of the graphitized CNT yarn. Crystallinity of the CNT yarn was improved more than ten times, and defect structures and impure materials was removed by the graphitization treatment. As a result of single fiber tensile tests, strength of the yarn was increased by 20~35% after the graphitization. On the other hand, strength of the CNT composing the yarn was decreased. The breaking form of the CNT yarn was changed from pulling out of CNT bundles to rapture of the bundles by the graphitization, indicating an increase of interactive force between the bundles. In addition, as a result of pulling out simulations by molecular dynamics method, it was indicated that the pulling out of the CNT bundles were suppressed by increase in van der Waals force. Consequently, the improvement of mechanical properties of the untwisted CNT yarns was not due to the change in the strength of the CNT in the yarns but the main cause was the increase in the interactive force between the CNTs.</p>
Fracture behavior of diamondlike carbon films deposited on polymer substrates Peer-reviewed

Go Yamamoto, Tomonaga Okabe, Noriaki Ikenaga

Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films　36　(2)　Article No. 02C101　2018/03/01
Publisher: AVS Science and Technology Society
DOI： 10.1116/1.5003683 　

ISSN： 1520-8559 0734-2101
Determination of full elastic constants of carbon fiber in carbon fiber reinforced plastic composites

Go Yamamoto, Shogo Kurisaki, Satoshi Atobe, Tomonaga Okabe

33rd Technical Conference of the American Society for Composites 2018　3　1508-1514　2018
Publisher: DEStech Publications Inc.
Development of large-movements and high-force electrothermal bimorph actuators based on aligned carbon nanotube reinforced epoxy composites Peer-reviewed

Keiichi Shirasu, Go Yamamoto, Yoku Inoue, Toshio Ogasawara, Yoshinobu Shimamura, Toshiyuki Hashida

SENSORS AND ACTUATORS A-PHYSICAL　267　455-463　2017/11

DOI： 10.1016/j.sna.2017.10.051 　

ISSN： 0924-4247
Is the tensile strength of carbon nanotubes enhanced by supported materials?: Effect of supported amorphous alumina nanoparticles on the tensile strength of carbon nanotubes Peer-reviewed

Tatsuhito Kimura, Hideaki Suzuki, Mei Zhang, Go Yamamoto, Toshiyuki Hashida, Kenichi Motomiya, Kazuyuki Tohji, Yoshinori Sato

CARBON　118　(1)　339-342　2017/07

DOI： 10.1016/j.carbon.2017.03.057 　

ISSN： 0008-6223

eISSN： 1873-3891
Key factors limiting carbon nanotube strength: Structural characterization and mechanical properties of multi-walled carbon nanotubes Peer-reviewed

Keiichi SHIRASU, Itaru TAMAKI, Takamichi MIYAZAKI, Go YAMAMOTO, Raman BEKAREVICH, Kaori HIRAHARA, Yoshinobu SHIMAMURA, Yoku INOUE, Toshiyuki HASHIDA

Mechanical Engineering Journal (in press)　4　(5)　2017/06/21

DOI： 10.1299/mej.17-00029 　

ISSN： 2187-9745
Potential use of CNTs for production of zero thermal expansion coefficient composite materials: An experimental evaluation of axial thermal expansion coefficient of CNTs using a combination of thermal expansion and uniaxial tensile tests Peer-reviewed

Keiichi Shirasu, Akihiro Nakamura, Go Yamamoto, Toshio Ogasawara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING　95　152-160　2017/04

DOI： 10.1016/j.compositesa.2016.12.027 　

ISSN： 1359-835X

eISSN： 1878-5840
多層カーボンナノチューブの強度・破壊特性評価と構造欠陥の影響に関する研究 Peer-reviewed

玉木格, 白須圭一, 宮崎孝道, 山本剛, Raman Bekarevich, 平原佳織, 島村佳伸, 井上翼, 橋田俊之

日本機械学会論文集　83　(847)　16-00283　2017/03/25

DOI： 10.1299/transjsme.16-00283 　

ISSN： 2187-9761
Influence of supported PtPd nanoparticles on the tensile strength of individual multi-walled carbon nanotubes: strength decrease by the interaction of metal and nanotube Peer-reviewed

Hideaki Suzuki, Tatsuhito Kimura, Go Yamamoto, Toshiyuki Hashida, Kenichi Motomiya, Kazuyuki Tohji, Yoshinori Sato

RSC ADVANCES　7　(79)　49917-49922　2017

DOI： 10.1039/c7ra09340c 　

ISSN： 2046-2069
多層カーボンナノチューブの強度・破壊特性評価と構造欠陥の影響に関する研究 Invited

玉木格, 白須圭一, 宮崎孝道, 山本剛, Raman Bekarevich, 平原佳織, 島村佳伸, 井上翼, 橋田俊之

日本機械学会論文集　83　(847)　Article No. 16-00283　2017/01
円孔を有する不連続炭素繊維強化熱可塑性プラスチックの引張強度予測 Peer-reviewed

山本剛, 坂本鎌治, 岡部朋永, 橋本雅弘, 平野啓之

日本複合材料学会誌　43　(3)　104-111　2017
Publisher:
DOI： 10.6089/jscm.43.104 　

ISSN： 0385-2563
Multi-objective optimization for resin transfer molding process Peer-reviewed

Tomonaga Okabe, Yutaka Oya, Go Yamamoto, Junki Sato, Tsubasa Matsumiya, Ryosuke Matsuzaki, Shigeki Yashiro, Shigeru Obayashi

COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING　92　(1)　1-9　2017/01

DOI： 10.1016/j.compositesa.2016.09.023 　

ISSN： 1359-835X

eISSN： 1878-5840
First-principles study of interfacial interaction between carbon nanotube and Al2O3(0001) Peer-reviewed

Irfan Dwi Aditya, Daisuke Matsunaka, Yoji Shibutani, Go Yamamoto

JOURNAL OF APPLIED PHYSICS　121　(2)　Article number 025304　2017/01

DOI： 10.1063/1.4973741 　

ISSN： 0021-8979

eISSN： 1089-7550
Friction and wear properties of carbon nanotube/alumina composites under water lubricated conditions Peer-reviewed

Keiichi Shirasu, Takuto Miyaura, Go Yamamoto, Toshiyuki Hashida

Proceedings of the 21th International Conference on Composite Materials　2017
In-situ characterization of interfacial shear strength in multi-walled carbon nanotube reinforced aluminum matrix composites Peer-reviewed

Weiwei Zhou, Go Yamamoto, Yuchi Fan, Hansang Kwon, Toshiyuki Hashida, Akira Kawasaki

CARBON　106　37-47　2016/09

DOI： 10.1016/j.carbon.2016.05.015 　

ISSN： 0008-6223

eISSN： 1873-3891
CFRPの層間靱性に及ぼすCNT添加の影響評価 Peer-reviewed

吉岡健一, Felix NGUYEN, Swezin THAN TUN, 山本剛, 岡部朋永

日本複合材料学会誌　42　(5)　193-200　2016/09
Publisher: JAPAN SOCIETY FOR COMPOSITE MATERIALS
DOI： 10.6089/jscm.42.193 　

ISSN： 0385-2563

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In this study, two types of carbon nanotube (CNT) with different types of CNT alignment are used as an interlaminar toughener for carbon fiber reinforced plastics (CFRP) preparation, and effects of CNT addition on the interlaminar fracture toughness of CFRP are investigated. The effects of the interlaminar toughening by addition of a thermoplastic resins are also investigated in addition to the above-mentioned CNT loading. It is well known that the impact resistance, i.e., interlaminar fracture toughness, is one of the most important properties for the development of CFRP. Even though the improvement in the interlaminar fracture toughness have been reported by adding thermoplastic resin between CFRP layers, further research is needed for the development of CFRP with lightweight and improved interlaminar fracture toughness. On the basis of these backgrounds, in this study, the effects of the CNT addition (unidirectionally aligned and randomly oriented CNTs), number of CNT layers (25 and 100 plies), location of CNT layer and thermoplastic resin addition on the mode I and mode II interlaminar fracture toughness are explored.
ばね要素モデルを用いた一方向炭素繊維/エポキシ複合材料の引張強度予測 Peer-reviewed

渡邉潤, 田中文彦, 松谷浩明, 奥田治己, 津田皓正, 樋口諒, 山本剛, 岡部朋永

材料システム　34　15-19　2016/03/15
Publisher:
ISSN： 0286-6013
Preparation and Performance Evaluation of Electrothermal Actuators using Aligned Carbon Nanotube Reinforced Epoxy Composites Peer-reviewed

Keiichi Shirasu, Akihiro Nakamura, Go Yamamoto, Toshio Ogasawara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

Mechanical Engineering Journal　3　(4)　15-00607-15-00607　2016/01/21
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/mej.15-00607 　

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<p>By using an aligned multi-walled carbon nanotube (MWCNT) reinforced epoxy composite, an electrothermal bimorph actuator was fabricated and its load and deformation capacities were investigated. The composite has a negative coefficient of thermal expansion (CTE) as well as large Young's modulus. To evaluate the actuator property, a composite/aluminum laminate was prepared and a U-shaped actuator was formed by cutting off the middle part of the composite/aluminum laminate. The Young's modulus of the composites increased linearly with increasing MWCNT volume fraction, and that of the composite containing 27 vol.% MWCNTs reached 56.8 ± 3.9 GPa. We also demonstrated that the actuator showed a large bending displacement and force output under low voltage stimulation. The bending displacement and force output of the actuator with the free length of 16 mm reached 7.6 mm and 9.0 mN under a DC voltage of 5.2 V, respectively. Furthermore, the actuator fabricated in this study showed higher values of work output per unit volume compared to the actuators reported in previous studies within the frequency between 0.05 Hz and 0.5 Hz. The enhanced performance was attributable mainly to the high Young's modulus of both composite and aluminum layers and the huge mismatch of the coefficient of thermal expansion in the composite/aluminum laminate.</p>
Evaluation of Tensile Properties of Multi-Walled Carbon Nanotubes Synthesized by Chemical Vapor Deposition Peer-reviewed

Itaru Tamaki, Keiichi Shirasu, Takamichi Miyazaki, Go Yamamoto, Raman Bekarevich, Kaori Hirahara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

Proc. of Asia-Pacific Conference on Fracture and Strength 2016 (APCFS2016)　2016
多層カーボンナノチューブにおける軸方向線膨張係数の温度依存性に関する研究（配向カーボンナノチューブ/エポキシ複合材料の線膨張測定に基づく手法） Peer-reviewed

白須圭一, 中村彰宏, 山本剛, 小笠原俊夫, 島村佳伸, 井上翼, 橋田俊之

日本機械学会論文集　82　(844)　16-00228　2016

DOI： 10.1299/transjsme.16-00228 　
Negative axial thermal expansion coefficient of carbon nanotubes: Experimental determination based on measurements of coefficient of thermal expansion for aligned carbon nanotube reinforced epoxy composites Peer-reviewed

Keiichi Shirasu, Go Yamamoto, Itaru Tamaki, Toshio Ogasawara, Yoshinobu Shimamura, Yoku Inoue, Toshiyuki Hashida

CARBON　95　904-909　2015/12

DOI： 10.1016/j.carbon.2015.09.026 　

ISSN： 0008-6223

eISSN： 1873-3891
Proposal of Collaborative Research focusing on Interfacial Science of Cellulose and Plastic Aiming for Creation of Natural Fiber Reinforced Composites

Hiroyuki Kosukegawa, Go Yamamoto, Tetsuya Uchimoto, Fredrik Lundell, Toshiyuki Takagi

International Workshop on Flow Dynamics & Spintronics　2015/11/13
Effects of processing conditions on microstructure, electrical conductivity and mechanical properties of MWCNT/alumina composites prepared by flocculation Peer-reviewed

Weili Wang, Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Toshiyuki Hashida

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY　35　(14)　3903-3908　2015/11

DOI： 10.1016/j.jeurceramsoc.2015.06.027 　

ISSN： 0955-2219

eISSN： 1873-619X
Relationship between microstructure and mechanical properties in acid-treated carbon nanotube-reinforced alumina composites Peer-reviewed

Keiichi Shirasu, Go Yamamoto, Yo Nozaka, Weili Wang, Toshiyuki Hashida

JOURNAL OF MATERIALS SCIENCE　50　(20)　6688-6699　2015/10

DOI： 10.1007/s10853-015-9223-6 　

ISSN： 0022-2461

eISSN： 1573-4803
Microstructuring of carbon nanotubes-nickel nanocomposite Peer-reviewed

Zhonglie An, Liang He, Masaya Toda, Go Yamamoto, Toshiyuki Hashida, Takahito Ono

Nanotechnology　26　(19)　195601 (8pp)　2015/05/15

DOI： 10.1088/0957-4484/26/19/195601 　

ISSN： 0957-4484

eISSN： 1361-6528
Synthesis of carbon nanotubes-Ni composite for micromechanical elements application Peer-reviewed

Zhonglie An, Masaya Toda, Go Yamamoto, Toshiyuki Hashida, Takahito Ono

Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS)　2015-February　(February)　401-404　2015/02/26

DOI： 10.1109/MEMSYS.2015.7050974 　

ISSN： 1084-6999
Fabrication and characterization of silicon micromirror with carbon nanotubes-nickel nanocomposite beams Peer-reviewed

Zhonglie An, Masaya Toda, Go Yamamoto, Toshiyuki Hashida, Takahito Ono

Proceedings of the IEEE Conference on Nanotechnology　888-892　2014/11/26

DOI： 10.1109/NANO.2014.6968008 　

eISSN： 1944-9399
Inclined slit-based pullout method for determining interfacial strength of multi-walled carbon nanotube-alumina composites Peer-reviewed

Yo Nozaka, Weili Wang, Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

CARBON　78　439-445　2014/11

DOI： 10.1016/j.carbon.2014.07.024 　

ISSN： 0008-6223

eISSN： 1873-3891
Microstructure-property relationships in pressureless-sintered carbon nanotube/alumina composites Peer-reviewed

Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Weili Wang, Toshiyuki Hashida

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING　617　179-186　2014/11

DOI： 10.1016/j.msea.2014.08.068 　

ISSN： 0921-5093

eISSN： 1873-4936
Resonant Silicon Micromirror with Electrophated Carbon Nanotubes-Nickel Composite Beams for MEMS Application

Ahonglie An, Masaya Toda, Go Yamamoto, Toshiyuki Hashida, Takahito Ono

The IEEE International Nanoelectonics Conference　6　173　2014/07/28
Tensile mechanical properties of carbon nanotube/epoxy composite fabricated by pultrusion of carbon nanotube spun yarn preform Peer-reviewed

Yoshinobu Shimamura, Kahori Oshima, Keiichiro Tohgo, Tomoyuki Fujii, Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida, Ken Goto, Toshio Ogasawara, Kimiyoshi Naito, Takayuki Nakano, Yoku Inoue

COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING　62　32-38　2014/07

DOI： 10.1016/j.compositesa.2014.03.011 　

ISSN： 1359-835X

eISSN： 1878-5840
Structural and Electrochemical Characterization of Ethylenediaminated Single-Walled Carbon Nanotubes Prepared from Fluorinated SWCNTs Peer-reviewed

Kohei Bushimata, Shin-ichi Ogino, Kazutaka Hirano, Tatsuhiro Yabune, Kenta Sato, Takashi Itoh, Kenichi Motomiya, Koji Yokoyama, Daiki Mabuchi, Hikaru Nishizaka, Go Yamamoto, Toshiyuki Hashida, Kazuyuki Tohji, Yoshinori Sato

JOURNAL OF PHYSICAL CHEMISTRY C　118　(27)　14948-14956　2014/07

DOI： 10.1021/jp503124n 　

ISSN： 1932-7447
Shytheisis and Characterization of Carbon Nanotube-Nickel Composite with High Content of Carbon Nanotubes

Zhonglie An, Masaya Toda, Go Yamamoto, Toshiyuki Hashida, Takahito Ono

The Asia-Pacific Conference on Transducers and Micro/Nano Technologies　7　14-5　2014/06/29
FABRICATION AND MECHANICAL EVALUATION OF ALIGNED MULTI-WALLED CARBON NANOTUBE SHEET/ALUMINA LAMINATED CERAMIC COMPOSITES Peer-reviewed

G. Yamamoto, K. Shirasu, Y. Nozaka, Y. Shimamura, Y. Inoue, T. Hashida

Proceedings of the 16th European Conference on Composite Materials　2014
MICROSTRUCTURE AND MECHANICAL PROPERTIES OF MULTI-WALLED CARBON NANOTUBE/ALUMINA COMPOSITES PREPARED BY A NOVEL FLOCCULATION METHOD Peer-reviewed

W.L. Wang, G. Yamamoto, K. Shirasu, Y. Nozaka, T. Hashida

Proceedings of the 16th European Conference on Composite Materials　2014
Structure-property relationships in thermally-annealed multi-walled carbon nanotubes Peer-reviewed

Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Yoshinori Sato, Toshiyuki Takagi, Toshiyuki Hashida

CARBON　66　219-226　2014/01

DOI： 10.1016/j.carbon.2013.08.061 　

ISSN： 0008-6223

eISSN： 1873-3891
Pull-out simulations of a capped carbon nanotube in carbon nanotube-reinforced nanocomposites Peer-reviewed

Y. Li, S. Liu, N. Hu, X. Han, L. Zhou, H. Ning, L. Wu, Alamusi, G. Yamamoto, C. Chang, T. Hashida, S. Atobe, H. Fukunaga

Journal of Applied Physics　113　(14)　144304 (7pp)　2013/04/14

DOI： 10.1063/1.4800110 　

ISSN： 0021-8979
Development of Pressureless Sintering Method for Carbon Nanotube/Alumina Composites and Their Microstructure-Property Relationships Peer-reviewed

Go YAMAMOTO, Keiichi SHIRASU, Yo NOZAKA, Takahumi NAKAMURA, Toshiyuki HASHIDA

Journal of Solid Mechanics and Materials Engineering　7　(3)　394-402　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/immp.7.394 　

ISSN： 1880-9871

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Multi-walled carbon nanotube (MWCNT)/alumina composites with different amounts of MWCNTs were prepared by a simple mechanical mixing method followed by a pressureless sintering. The effects of microstructures including grain size, MWCNT location, fracture patterns of the matrix and dispersibility of MWCNTs on the mechanical properties of the resultant composites were investigated. It was demonstrated from microstructural observations and fracture tests of the composites that grain size, MWCNT location and fracture patterns had no significant impact on the mechanical properties of the composites prepared under the processing conditions used in this research. In contrast, the state of MWCNT dispersion within the composites was shown to be one of the important factors affecting the strength and toughness enhancement in our composites. The dispersibility of MWCNTs decreased monotonically as a function of MWCNT volume fraction. The degradation in the mechanical properties observed for the composites with a higher amount of MWCNTs was shown to be associated with the dispersibility of MWCNTs, and a MWCNT agglomerate was anticipated to act as imperfections and led to a reduction of mechanical properties.
Evaluation of mechanical properties and microstructures of multi-walled carbon Nanotube/Alumina composites prepared by pressureless sintering Peer-reviewed

Yo Nozaka, Go Yamamoto, Keiichi Shirasu, Mamoru Omori, Toshiyuki Takagi, Toshiyuki Hashida

Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　79　(802)　764-768　2013

DOI： 10.1299/kikaia.79.764 　

ISSN： 0387-5008
Effects of annealing treatment of carbon nanotube on the fracture properties of carbon Nanotube/Alumina composites Peer-reviewed

Keiichi Shirasu, Go Yamamoto, Yo Nozaka, Mamoru Omori, Toshiyuki Hashida

Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　79　(802)　706-710　2013

DOI： 10.1299/kikaia.79.706 　

ISSN： 0387-5008
Prediction of pull-out force of multi-walled carbon nanotube (MWCNT) in sword-in-sheath mode Peer-reviewed

Go Yamamoto, Sen Liu, Ning Hu, Toshiyuki Hashida, Yaolu Liu, Cheng Yan, Yuan Li, Hao Cui, Huiming Ning, Liangke Wu

COMPUTATIONAL MATERIALS SCIENCE　60　7-12　2012/07

DOI： 10.1016/j.commatsci.2012.03.016 　

ISSN： 0927-0256
Influence of the structure of the nanotube on the mechanical properties of binder-free multi-walled carbon nanotube solids Peer-reviewed

Yoshinori Sato, Hikaru Nishizaka, Shunichi Sawano, Atsushi Yoshinaka, Kazutaka Hirano, Shinji Hashiguchi, Takayuki Arie, Seiji Akita, Go Yamamoto, Toshiyuki Hashida, Hisamichi Kimura, Kenichi Motomiya, Kazuyuki Tohji

CARBON　50　(1)　34-39　2012/01

DOI： 10.1016/j.carbon.2011.07.047 　

ISSN： 0008-6223
Effects of surface modification of carbon nanotube on the mechanical properties of multi-walled carbon nanotube/alumina composites Peer-reviewed

Go Yamamoto, Keiichi Shirasu, Yo Nozaka, Mamoru Omori, Toshiyuki Takagi, Toshiyuki Hashida

Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　78　(790)　843-854　2012

DOI： 10.1299/kikaia.78.843 　

ISSN： 0387-5008
MEASUREMENTS OF CARBON NANOTUBE TENSILE STRENGTH AND MECHANICAL PROPERTIES OF CARBON NANOTUBE/ALUMINA COMPOSITES PREPARED BY PRESSURELESS SINTERING Peer-reviewed

G. Yamamoto, K. Shirasu, Y. Nozaka, T. Takagi, T. Hashida

Proceedings of the 15th European Conference on Composite Materials　2012
FABRICATION AND EVALUATION OF CARBON NANOTUBE/ALUMINA COMPOSITES BY PRECURSOR METHOD Peer-reviewed

K. Shirasu, G. Yamamoto, Y. Nozaka, M. Omori, T. Hashida

Proceedings of the 15th European Conference on Composite Materials　2012
Nanotube fracture during the failure of carbon nanotube/alumina composites Peer-reviewed

Go Yamamoto, Keiichi Shirasu, Toshiyuki Hashida, Toshiyuki Takagi, Ji Won Suk, Jinho An, Richard D. Piner, Rodney S. Ruoff

CARBON　49　(12)　3709-3716　2011/10

DOI： 10.1016/j.carbon.2011.04.022 　

ISSN： 0008-6223
Investigation on CNT/alumina interface properties using molecular mechanics simulations Peer-reviewed

Sen Liu, Ning Hu, Go Yamamoto, Yindi Cai, Yajun Zhang, Yaolu Liu, Yuan Li, Toshiyuki Hashida, Hisao Fukunaga

CARBON　49　(11)　3701-3704　2011/09

DOI： 10.1016/j.carbon.2011.04.059 　

ISSN： 0008-6223
Boron-Assisted Transformation to Rod-Like Graphitic Carbons from Multi-Walled Carbon Nanotubes in Boron-Mixed Multi-Walled Carbon Nanotube Solids Peer-reviewed

Yoshinori Sato, Hikaru Nishizaka, Kenichi Motomiya, Go Yamamoto, Akira Okubo, Hisamichi Kimura, Mikio Ishikuro, Kazuaki Wagatsuma, Toshiyuki Hashida, Kazuyuki Tohji

ACS APPLIED MATERIALS & INTERFACES　3　(7)　2431-2439　2011/07

DOI： 10.1021/am200335n 　

ISSN： 1944-8244
単繊維引抜き試験によるカーボンナノチューブ/アルミナ複合材料のクラックブリッジング挙動特性評価 Peer-reviewed

山本剛, 白須圭一, 高木敏行, 橋田俊之

日本機械学会論文集(A編)　77　(777)　779-783　2011
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaia.77.779 　

ISSN： 0387-5008

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The crack bridging behavior of multi-walled carbon nanotube-reinforced alumina matrix composites has been investigated using a single fiber pullout testing method. Contradictory to the conventional understanding (which have reported that pullout phenomena evidently occurred in the bulk nanotube-reinforced alumina composites), the pullout experiments using an in situ SEM method with a nanomanipulator system demonstrated that strong load transfer was revealed, and no pullout behavior was observed for all 15 MWCNTs. The MWCNTs, rather than pulling out from the alumina matrix, broke in the outer-shells and the inner section was pulled away, leaving the outer-shells of the fragment in the matrix. This implies that tougher ceramics with MWCNT can be obtained by creating the appropriate interaction between the matrix and MWCNT: not too week but also not too strong to permit an adequate load transfer between the two parts and thus a consequent pulling out without breakage of MWCNT. Our finding suggests important implications for the design of tougher ceramic composites with MWCNTs. The important factor for such tougher ceramic composites will thus be the use of 'strong' MWCNTs having higher mechanical performance (as well as a good dispersion in the matrix).
カーボンナノチューブ/アルミナ複合材料の強度特性に及ぼすカーボンナノチューブ表面修飾の影響と破壊過程に関する研究 Peer-reviewed

白須圭一, 山本剛, 大森守, 相沢養市, 橋田俊之

日本機械学会論文集(A編)　77　(777)　774-778　2011
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaia.77.774 　

ISSN： 0387-5008

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We report the mechanical properties and microstructures of multi-walled carbon nanotube (MWCNT)/alumina composites made with MWCNTs that absorb negatively charged functional groups at the MWCNT ends and along their length from an acid treatment. We conducted the fracture surface observations of the composites, in order to evaluate the effects of the acid treatment conditions of MWCNTs on the mechanical properties of the composites and the microstructures such as dispersibility and protrusion length of MWCNTs. According to the SEM observations, it was found that the dispersibility of MWCNTs affected the mechanical properties of the composites, and the protrusion length of MWCNTs decreased with increasing of the acid treatment time of MWCNTs. These observations revealed that the high structural homogeneity rather than pullout behavior of MWCNTs leads to an increase in the mechanical properties of the MWCNT/alumina composite. There is an optimal acid treatment time for improving the mechanical properties of the composites. The dispersibility of the MWCNTs and mechanical properties of the composites was increased by the acid treatment with treated for 2 hours compared to the pristine MWCNTs and acid treatment MWCNTs with treated for 0, 0.5, 1, 3 and 4 hours.
Preparation of carbon nanotube reinforced alumina composites and examination of their fracture mechanisms Peer-reviewed

Keiichi Shirasu, Go Yamamoto, Mamoru Omori, Toshiyuki Takagi, Toshiyuki Hashida

Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　77　(779)　1041-1045　2011

DOI： 10.1299/kikaia.77.1041 　

ISSN： 0387-5008
Molecular mechanics simulation of the sliding behavior between nested walls in a multi-walled carbon nanotube Peer-reviewed

Yuan Li, Ning Hu, Go Yamamoto, Zhongchang Wang, Toshiyuki Hashida, Hiroshi Asanuma, Chensong Dong, Tomonaga Okabe, Masahiro Arai, Hisao Fukunaga

CARBON　48　(10)　2934-2940　2010/08

DOI： 10.1016/j.carbon.2010.04.031 　

ISSN： 0008-6223
The influence of nanoscale defects on the fracture of multi-walled carbon nanotubes under tensile loading Peer-reviewed

Go Yamamoto, Ji Won Suk, Jinho An, Richard D. Piner, Toshiyuki Hashida, Toshiyuki Takagi, Rodney S. Ruoff

DIAMOND AND RELATED MATERIALS　19　(7-9)　748-751　2010/07

DOI： 10.1016/j.diamond.2010.01.045 　

ISSN： 0925-9635
Effects of Sintering Additive on Mechanical Properties of Alumina Matrix Composites Reinforced with Carbon Nanotubes Peer-reviewed

Go YAMAMOTO, Mamoru OMORI, Toshiyuki HASHIDA, Hisamichi KIMURA, Toshiyuki TAKAGI

Journal of Solid Mechanics and Materials Engineering　4　(3)　460-469　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jmmp.4.460 　

ISSN： 1880-9871

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Carbon nanotube is nature's smallest fiber and predicted to have a range of unusual mechanical and electrical properties. One possible route to harnessing these properties for applications would be to incorporate nanotubes in a composite material. Here, we report the mechanical properties of multi-walled carbon nanotube (MWCNT) reinforced alumina composites made with a pristine MWCNT and an acid-treated version that have nanoscale defects on their surfaces from an acid treatment. It was demonstrated that surface modification of the MWCNT is effective in improvement of bending strength and fracture toughness of the MWCNT-reinforced alumina composites. On the basis of the results, we also prepared three sets of the acid-treated MWCNT-reinforced alumina composites having different sintering additives, in order to investigate the effects of sintering additives on their microstructures and mechanical properties. Mechanical properties of the composites were dependent mostly on the type of sintering additives and amount of MWCNT. The 0.9 vol.% acid-treated MWCNT-reinforced alumina composites with MgO sintering additive gave the highest bending strength (689.6 ± 29.1 MPa) and fracture toughness (5.90 ± 0.27 MPa·m^1/2), respectively.
A novel structure for carbon nanotube reinforced alumina composites effects of sintering additives on the mechanical properties Peer-reviewed

Go Yamamoto, Mamoru Omori, Yoichi Aizawa, Toshiyuki Hashida, Toshiyuki Takagi

Nihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A　76　(764)　416-418　2010
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/kikaia.76.416 　

ISSN： 0387-5008
Reinforcement of Alumina with Surface Modified Carbon Nanotubes Peer-reviewed

Go Yamamoto, Toshiyuki Hashida, Mamoru Omori, Hisamichi Kimura

MULTISCALE, MULTIFUNCTIONAL AND FUNCTIONALLY GRADED MATERIALS　631-632　231-+　2010

DOI： 10.4028/www.scientific.net/MSF.631-632.231 　

ISSN： 0255-5476
Preparation and characterization of lanthanum carbide encapsulated carbon nanocapsule/lanthanum hexaboride nanocomposites Peer-reviewed

Masaru Namura, Ippei Waki, Yoshinori Sato, Go Yamamoto, Akira Okubo, Hisamichi Kimura, Naohisa Osaka, Kenichi Motomiya, Toshiyuki Hashida, Balachandran Jeyadevan, Kazuyuki Tohji

MATERIALS LETTERS　63　(15)　1307-1310　2009/06

DOI： 10.1016/j.matlet.2009.03.006 　

ISSN： 0167-577X
Preparation and Microstructure of Carbon Nanotube-Toughened Alumina Composites Peer-reviewed

Go YAMAMOTO, Toshiyuki HASHIDA, Mamoru OMORI, Hisamichi KIMURA

Journal of Solid Mechanics and Materials Engineering　3　(2)　85-95　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jmmp.3.85 　

ISSN： 1880-9871

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Engineering ceramics have high stiffness, excellent thermostability and relatively low density, but their brittleness impedes their use as structural materials. Incorporating carbon nanotubes (CNTs) into a brittle ceramic might be expected to produce CNT/ceramic composites with both high toughness and high temperature stability. Until now, however, materials fabrication difficulties have limited research on CNT/ceramic composites. The mechanical failure of CNT/ceramic composites reported previously is primarily attributed to poor CNTs-matrix connectivity and severe phase segregation. The connectivity with, and uniform distribution within the matrix are essential structural requirements for the stronger and tougher CNT/ceramic composites. Here we show that a novel processing approach based on the precursor method for synthesis of Al₂O₃ and acid-treated multi-walled carbon nanotubes (MWCNTs) can diminish the phase segregation, and render MWCNT/Al₂O₃ composites highly homogeneous. Combined with mechanical interlock induced by the chemically modified MWCNTs, this approach leads to improved mechanical properties. Direct toughness measurements, using the single edge notched beam method, reveal that only 0.9 vol.% acid-treated MWCNT addition results in 25% increases in fracture toughness (5.90±0.27 MPa·m^1/2).
A novel structure for carbon nanotube reinforced alumina composites with improved mechanical properties Peer-reviewed

G. Yamamoto, M. Omori, T. Hashida, H. Kimura

NANOTECHNOLOGY　19　(31)　315708 (7pp)　2008/08

DOI： 10.1088/0957-4484/19/31/315708 　

ISSN： 0957-4484
Mechanical properties and structural characterization of carbon nanotube/alumina composites prepared by precursor method Peer-reviewed

Go Yamamoto, Mamoru Omori, Kenji Yokomizo, Toshiyuki Hashida

DIAMOND AND RELATED MATERIALS　17　(7-10)　1554-1557　2008/07

DOI： 10.1016/j.diamond.2008.01.059 　

ISSN： 0925-9635
Tribological properties of single-walled carbon nanotube solids Peer-reviewed

Go Yamamoto, Toshiyuki Hashida, Koshi Adachi, Toshiyuki Takagj

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY　8　(5)　2665-2670　2008/05

DOI： 10.1166/jnn.2008.295 　

ISSN： 1533-4880
The electrical properties of polymer nanocomposites with carbon nanotube fillers Peer-reviewed

Ning Hu, Zen Masuda, Cheng Yan, Go Yamamoto, Hisao Fukunaga, Toshiyuki Hashida

NANOTECHNOLOGY　19　(21)　215701 (10pp)　2008/05

DOI： 10.1088/0957-4484/19/21/215701 　

ISSN： 0957-4484

eISSN： 1361-6528
Novel selective dyeing method for chrysotile asbestos detection in concrete materials Peer-reviewed

Yoshihiko Oke, Nakamichi Yamasaki, Go Yamamoto, Kazuhiro Sasaki, Naomi Maeta, Hirokazu Fujimaki, Toshiyuki Hashida

ENVIRONMENTAL SCIENCE & TECHNOLOGY　42　(5)　1638-1642　2008/03

DOI： 10.1021/es071805a 　

ISSN： 0013-936X
Structural characterization and frictional properties of carbon nanotube/alumina composites prepared by precursor method Peer-reviewed

Go Yamamoto, Mamoru Omori, Kenji Yokomizo, Toshiyuki Hashida, Koshi Adachi

MATERIALS SCIENCE AND ENGINEERING B-ADVANCED FUNCTIONAL SOLID-STATE MATERIALS　148　(1-3)　265-269　2008/02

DOI： 10.1016/j.mseb.2007.09.013 　

ISSN： 0921-5107
Super-robust, lightweight, conducting carbon nanotube blocks cross-linked by de-fluorination Peer-reviewed

Yoshinori Sato, Makoto Ootsubo, Go Yamamoto, Gregory Van Lier, Mauricio Terrones, Shinji Hashiguchi, Hisamichi Kimura, Akira Okubo, Kenichi Motomiya, Balachandran Jeyadevan, Toshiyuki Hashida, Kazuyuki Tohji

ACS NANO　2　(2)　348-356　2008/02

DOI： 10.1021/nn700324z 　

ISSN： 1936-0851
Effect of fabrication process on electrical properties of polymer/multi-wall carbon nanotube nanocomposites Peer-reviewed

Ning Hu, Zen Masuda, Go Yamamoto, Hisao Fukunaga, Toshiyuki Hashida, Jinghao Qiu

COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING　39　(5)　893-903　2008

DOI： 10.1016/j.compositesa.2008.01.002 　

ISSN： 1359-835X
Preparation of carbon nanotube - Toughened alumina composites Peer-reviewed

G. Yamamoto, M. Omori, T. Hashida

WATER DYNAMICS　987　83-+　2008

ISSN： 0094-243X
Polycarbosilane-derived SiC/single-walled carbon nanotube nanocomposites Peer-reviewed

Go Yamamoto, Kenji Yokomizo, Mamoru Omori, Yoshinori Sato, Balachandran Jeyadevan, Kenichi Motomiya, Toshiyuki Hashida, Toru Takahashi, Akira Okubo, Kazuyuki Tohji

NANOTECHNOLOGY　18　(14)　145614 (5pp)　2007/04

DOI： 10.1088/0957-4484/18/14/145614 　

ISSN： 0957-4484
Tribological Properties of Single-Walled Carbon Nanotube Solids Peer-reviewed

Go Yamamoto, Toshiyuki Hashida, Koshi Adachi, Toshiyuki Takagi

Proceedings of The Seventh International Symposium on Advanced Fluid Information and The Fourth International Symposium on Transdisciplinary Fluid Integration, (Tohoku University, Sendai, Japan, December 14-15, 2007)　122-125　2007
The development of a novel immersion dyeing method for chrysotile asbestos in building materials Peer-reviewed

Yoshihiko Oke, Nakamichi Yamasaki, Go Yamamoto, Naomi Maeta, Hirokazu Fujimaki, Toshiyuki Hashida

Proc. of 1st Int. Sympo. on Aqua Science, Water Resource and Innovation Development of Countryside, (Sakawa, Kochi, Japan, November 26-30, 2007)　115-118　2007
Mechanical Properties of Single-Walled Carbon Nanotube Solids Prepared by Spark Plasma Sintering Peer-reviewed

Go YAMAMOTO, Yoshinori SATO, Toru TAKAHASHI, Mamoru OMORI, Kazuyuki TOHJI, Toshiyuki HASHIDA

Journal of Solid Mechanics and Materials Engineering　1　(7)　854-863　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jmmp.1.854 　

ISSN： 1880-9871

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In this paper, a spark plasma sintering (SPS) method was employed to solidify single-walled carbon nanotubes (SWCNTs) only, and the effect of processing conditions on the mechanical properties of the SWCNT solids were examined using a small punch (SP) testing method. The sintering temperatures used was in the range of 600∼1400°C, and the sintering pressures used was 40 MPa and 120 MPa. It was demonstrated that the SPS method allowed SWCNTs to be solidified, without any additives. The experimental results showed that the purification of raw soot was critically importance. The SWCNT solids prepared from purified raw soot showed significant non-linear deformation response, producing quasi-ductile fracture behavior. In contrast, raw soot produced brittle solids. The Young's modulus, fracture strength and work of fracture increased with the increasing sintering temperature and pressure. The Raman and SEM analyses showed that the amount of the graphite-like materials were observed to increase with the increasing temperature and pressure, which indicate that the structure of the SWCNTs was changed partially into the graphite-like materials. The formation of graphite-like materials increased tendency of brittle fracture in the SWCNT solids. TEM observations revealed that the fracture surfaces of the SWCNT solids were characterized by pull out of SWCNT bundles. This observation suggests that it may be possible to improve the mechanical properties of SWCNT solids by increasing the cohesion between SWCNTs.
Evaluation of tribological properties of binder-free single-walled carbon nanotube solids for solid lubrication applications Peer-reviewed

G. Yamamoto, T. Hashida, K. Adachi, Y. Sato, K. Tohji

WATER DYNAMICS　898　130-+　2007

DOI： 10.1063/1.2721263 　

ISSN： 0094-243X
Tribological and strength properties of alumina/multi-walled carbon nanotube composites Peer-reviewed

G. Yamamoto, K. Yokomizo, M. Omori, Y. Aizawa, T. Hashida

WATER DYNAMICS　898　154-+　2007

DOI： 10.1063/1.2721269 　

ISSN： 0094-243X
Estimation of the number of cross-links of multi-walled carbon nanotube films formed by a dehydration condensation reaction Peer-reviewed

S. Ogino, Y. Sato, G. Yamamoto, K. Sasamori, H. Kimura, T. Hashida, K. Motomiiya, B. Jeyadevan, K. Tohji

WATER DYNAMICS　898　175-+　2007

DOI： 10.1063/1.2721274 　

ISSN： 0094-243X
Relation of the number of cross-links and mechanical properties of multi-walled carbon nanotube films formed by a dehydration condensation reaction Peer-reviewed

Shin-ichi Ogino, Yoshinori Sato, Go Yamamoto, Kenichiro Sasamori, Hisamichi Kimura, Toshiyuki Hashida, Kenichi Motomiya, Balachandran Jeyadevan, Kazuyuki Tohji

JOURNAL OF PHYSICAL CHEMISTRY B　110　(46)　23159-23163　2006/11

DOI： 10.1021/jp0642387 　

ISSN： 1520-6106
Single-walled carbon nanotube-derived novel structural material Peer-reviewed

G Yamamoto, Y Sato, T Takahashi, M Omori, T Hashida, A Okubo, K Tohji

JOURNAL OF MATERIALS RESEARCH　21　(6)　1537-1542　2006/06

DOI： 10.1557/JMR.2006.0186 　

ISSN： 0884-2914
X-ray absorption fine structure (XAFS) analyses of Ni species trapped in graphene sheet of carbon nanofibers Peer-reviewed

Y. Sato, M. Ohtsubo, B. Jeyadevan, K. Tohji, K. Motomiya, R. Hatakeyama, G. Yamamoto, M. Omori, T. Hashida, K. Tamura, T. Akasaka, M. Uo, A. Yokoyama, F. Watari

Physical Review　B　(73)　144103-1-144103-11　2006/04

DOI： 10.1103/PhysRevB.73.144103 　
Mechanical properties of binder-free single-walled carbon nanotube solids Peer-reviewed

G Yamamoto, Y Sato, T Takahashi, M Omori, A Okubo, K Tohji, T Hashida

SCRIPTA MATERIALIA　54　(2)　299-303　2006/01

DOI： 10.1016/j.scriptamat.2005.03.053 　

ISSN： 1359-6462
Route to the synthesis of binder-free SWCNT solids with enhanced mechanical properties Peer-reviewed

G. Yamamoto, Y. Sato, M. Omori, K. Yokomizo, T. Hashida, T. Takahashi, A. Okubo, S. Watanabe, K. Tohji

FLOW DYNAMICS　832　425-+　2006

DOI： 10.1063/1.2204535 　

ISSN： 0094-243X
Synthesis and characterization of single-walled carbon nanotube/silicon carbide composites Peer-reviewed

G. Yamamoto, K. Yokomizo, M. Omori, Y. Sato, T. Takahashi, T. Hashida, K. Motomiya, A. Okubo, S. Watanabe, K. Tohji

WATER DYNAMICS　833　94-+　2006

DOI： 10.1063/1.2207083 　

ISSN： 0094-243X
Evaluation of mechanical properties of single-walled carbon nanotube solids prepared by spark plasma sintering Peer-reviewed

Go Yamamoto, Yoshinori Sato, Toru Takahashi, Mamoru Omori, Akira Okubo, Kazuyu Tohji, Toshiyuki Hashida

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy　52　(11)　826-830　2005/11

DOI： 10.2497/jjspm.52.826 　

ISSN： 0532-8799
Preparation of single- And multi-walled carbon nanotube solids and their mechanical properties Peer-reviewed

Go Yamamoto, Yoshinori Sato, Makoto Ohtsubo, Toru Takahashi, Mamoru Omori, Akira Okubo, Kazuyuki Tohji, Toshiyuki Hashida

Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy　52　(11)　831-835　2005/11

DOI： 10.2497/jjspm.52.831 　

ISSN： 0532-8799
Preparation of single-walled carbon nanotube solids and their mechanical properties Peer-reviewed

G Yamamoto, Y Sato, T Takahashi, M Omori, T Hashida, A Okubo, S Watanabe, K Tohji

JOURNAL OF MATERIALS RESEARCH　20　(10)　2609-2612　2005/10

DOI： 10.1557/JMR.2005.0345 　

ISSN： 0884-2914
Effects of polycarbosilane addition on the mechanical properties of single-walled carbon nanotube solids Peer-reviewed

G Yamamoto, M Omori, Y Sato, T Takahashi, K Tohji, T Hashida

JSME INTERNATIONAL JOURNAL SERIES A-SOLID MECHANICS AND MATERIAL ENGINEERING　48　(4)　189-193　2005/10

DOI： 10.1299/jsmea.48.189 　

ISSN： 1344-7912
放電プラズマ焼結法により作製した単層カーボンナノチューブバルク固化体の機械的特性 Peer-reviewed

山本剛, 佐藤義倫, 高橋亨, 大森守, 田路和幸, 橋田俊之

日本機械学会論文集(A編)　71　(702)　330-337　2005
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaia.71.330 　

ISSN： 0387-5008

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In this paper, a spark plasma sintering (SPS) method was employed to solidify single-walled carbon nanotubes (SWCNTs) only, and the effect of sintering conditions on the mechenical properties of the SWCNT solids were examined using a small punch (SP) testing method. The sintering temperature used in the range of 600-1 400°C, and the sintering pressure used 40 MPa and 120 MPa. It was demonstrated that the SPS method allowed SWCNTs to be solidified, without any additives. The experimental results showed that the purification of raw soot was critically importance. The SWCNT solid prepared from purified raw soot showed significant non-linear deformation response, producing quasi-ductile fracture behavior. In contrast, unpurified raw soot produced brittle SWCNT solids. The Young's modulus, fracture strength and work of fracture increased with increasing sintering temperature and pressure. The Raman scattering and SEM observations showed that the amount of the graphite-like materials were observed to increase with the increasing temperature and pressure, which indicate that the structure of the SWCNTs was changed partially into the graphite-like materials. The formation of graphite-like materials increased tendency of brittle fracture in the SWCNT solids. TEM observations revealed that the fracture surfaces of SWCNT solids were characterized by pull out of SWCNT bundles. This observation suggests that it may be possible to improve the mechanical properties of SWCNT solids by increasing the cohesion between SWCNTs.
Preparation of Single-Walled Carbon Nanotube Solids and Their Mechanical Properties Peer-reviewed

G. YAMAMOTO, Y. SATO, T. TAKAHASHI, M. OMORI, T. HASHIDA, A. OKUBO, S. WATANABE, K. TOHJI

Extended Abstracts of International Symposium on EcoTopia Science 2005 (ISETS05)　265-268　2005
カーボンナノチューブ固化体の作製と機械的特性の評価 Peer-reviewed

山本剛, 大坪誠, 佐藤義倫, 高橋亨, 大森守, 大久保昭, 田路和幸, 橋田俊之

傾斜機能材料論文集　17　25-30　2005
三点曲げ試験法による単層カーボンナノチューブ固化体の機械的特性評価 Peer-reviewed

山本剛, 佐藤義倫, 高橋亨, 大森守, 大久保昭, 田路和幸, 橋田俊之

傾斜機能材料論文集　17　31-36　2005
ＭＥＣＨＡＮＩＣＡＬ PROPERTIES AND MICROSTRUCTURAL INVASTIGATION OF SINGLE-WALLED CARBON NANOTUBE SOLIDS Peer-reviewed

G. Yamamoto, Y. Sato, T. Takahashi, M. Omori, K. Tohji, T. Hashida

2nd Int. Workshop on Water Dynamics　261-265　2004/11
Mechanical Properties of Single-Walled Ccarbon Nanotube Solid Prepared by Spark Plasma Sintering Method

G. Yamamoto, Y. Sato, T. Takahashi, M. Omori, K. Tohji, T. Hashida

1st International Workshop on WATER DYNAMICS　1　33-36　2004/03/17
単層カーボンナノチューブ焼結体の機械的特性に及ぼす不純物の影響 Peer-reviewed

山本剛, 大坪誠, 佐藤義倫, 高橋亨, 大森守, 田路和幸, 橋田俊之

傾斜機能材料論文集　16　157-162　2004
Biocompatibility of carbon nanotube disk Peer-reviewed

Y Sato, M Ohtsubo, B Jeyadevan, K Tohji, K Motomiya, R Hatakeyama, G Yamamoto, M Omori, T Hashida, K Tamura, T Akasaka, M Uo, A Yokoyama, F Watari

NANOSENSING: MATERIALS AND DEVICES　5593　623-627　2004

DOI： 10.1117/12.579687 　

ISSN： 0277-786X
PREPARATION AND BIOCOMPATIBILITY OF SINTERED CARBON NANOTUBE DISK Peer-reviewed

M. Ohtsubo, Y. Sato, B. Jeyadevan, K. Tohji, R. Hatakeyama, G. Yamamoto, M. Ohmori, T. Hashida, K. Tamura, T. Akasaka, M. Uo, A. Yokoyama, F. Watari

Proceedings of the International Symposium on Fullerenes, Nanotubes, and Carbon Nanoclusters, Fullerenes and nanotubes, materials for the new chemical frontier　243-248　2004

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Misc. 22

Effect of crystallinity on axial thermal expansion coefficient of carbon nanotubes: Experimental and simulation studies Peer-reviewed

Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

Proceedings of the 5th Asian Symposium on Materials and Processing　2018
142 Evaluation of Thermal Expansion Properties of Aligned Multi-Walled Carbon Nanotube Reinforced Epoxy Composites and its Application

NAKAMURA Akihiro, SHIRASU Keiichi, TAMAKI Itaru, YAMAMOTO Go, HASHIDA Toshiyuki

2016　(51)　81-82　2016
Publisher: The Japan Society of Mechanical Engineers
OS0525 Preparation and mechanical evaluation of aligned multi-walled carbon nanotube/epoxy composites

NAKAMURA Akihiro, SHIRASU Keiichi, YAMAMOTO Go, SHIMAMURA Yoshinobu, INOUE Yoku, HASHIDA Toshiyuki

2014　"OS0525-1"-"OS0525-3"　2014/07/19
Publisher: The Japan Society of Mechanical Engineers

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Two types of epoxy composites reinforced with an aligned multi-walled carbon nanotube (MWCNT) sheet and its thermal annealed analog were prepared and the effects of thermal annealing on the mechanical properties of the composites were investigated by conducting uniaxial tensile tests. The MWCNTs with lengths exceeding 1 mm were vertically grown on a Si substrate by chemical vapor deposition method, and were converted to horizontally aligned MWCNT sheets by pulling them out. The MWCNT sheets were then thermally-annealed at 2000℃ under Ar + 5% H_2 atmosphere. The composites containing annealed MWCNTs exhibited higher Young's modulus and tensile strength than those of the composites containing as-received MWCNTs. Uniaxial tensile experiments of individual MWCNTs revealed that thermal annealing led to an increase in Young's modulus, suggesting that the improvement in Young's modulus of the composites may be associated with the increase in the mechanical properties of individual MWCNTs. Young's modulus and tensile strength of the composites containing 22 vol.% annealed MWCNTs reached 94 ± 11 GPa and 474.2 ± 57.7 MPa, respectively.
GS21 Friction Properties of Multi-Walled Carbon Nanotube/Alumina Composites Prepared by Flocculation Method

NAKAMURA Takafumi, WANG Weili, SHIRASU Keiichi, YAMAMOTO Go, HASHIDA Toshiyuki

2014　"GS21-1"-"GS21-3"　2014/07/19
Publisher: The Japan Society of Mechanical Engineers

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Carbon nanotubes (CNTs) have extremely high tensile strength and elastic modulus, good flexibility and low density. In addition, CNTs are expected to have lubrication properties like other carbon-derived materials including graphite and diamond-like carbon. In this study, alumina ceramics reinforced with multi-walled CNTs (MWCNTs) were prepared by a flocculation method and the effects of the MWCNT content on mechanical and tribological properties of the composites were investigated. The results showed that the bending strength and fracture toughness simultaneously increased for the composite containing 10.0 vol.% MWCNTs. The friction coefficient of the composites containing 5.5 vol.% MWCNTs was about 0.15, measured by the ball-on-disk wear tests using alumina balls as a counterpart in air. Microstructural observations of the fractured and polished surfaces of the composites implied that the size of a MWCNTs agglomerate is one of the important factors for improving friction properties of the composite. It is suspected that there may be an optimal MWCNTs content for improving the mechanical and friction properties of the composites.
140 ナノ領域特性評価に基づくカーボンナノチューブ/アルミナ複合材料の破壊機構解明に関する研究

野坂陽, 王偉礼, 白須圭一, 山本剛, 橋田俊之

講演論文集　2014　(49)　81-82　2014
Publisher: 一般社団法人日本機械学会
カーボンナノチューブの機械的特性

山本剛, 白須圭一, 玉木格, 橋田俊之

日本複合材料学会誌　40　(6)　255-259　2014
SL10 Development of CNT Composite Materials

YAMAMOTO Go, SHIRASU Keiichi, NOZAKA Yo, OMORI Mamoru, TAKAGI Toshiyuki, HASHIDA Toshiyuki

2012　"SL10-1"-"SL10-3"　2012/09/22
Publisher: The Japan Society of Mechanical Engineers

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Carbon nanotubes (CNTs) have attracted enormous attention from many researchers of material science, and their physical properties have been intensively clarified. The next step of carbon nanotube research should be development of high performance CNT materials with industrial applications. Production of CNT composites represents one of great targets for the application. In this study, alumina has been selected as the matrix of CNT composites because of its low cost and high performance. The final goal is to develop a design-fabrication-evaluation methodology for CNT ceramic matrix composites and to produce high performance composites on the basis of the method to be developed. MWCNT/alumina composites were prepared by a simple mechanical mixing method followed by pressureless sintering. The effects of MWCNT addition on mechanical, tribological and electromagnetic-wave absorption properties of the pressureless sintered-MWCNT/alumina composites will be discussed.
GS37 Effects of Strength Properties and Dispersibility of Carbon Nanotube on the Fracture Properties of Carbon Nanotube/Alumina Composites

SHIRASU Keiichi, YAMAMOTO Go, NOZAKA Yo, OMORI Mamoru, TAKAGI Toshiyuki, HASHIDA Toshiyuki

2012　"GS37-1"-"GS37-3"　2012/09/22
Publisher: The Japan Society of Mechanical Engineers

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In this research, effects of the multi-walled carbon nanotubes (MWCNTs) addition on mechanical properties and microstructures of spark plasma-sintered MWCNT/alumina composites were investigated by using four types of MWCNTs that were annealed at different temperatures. The annealing temperatures were 1200, 1800, 2200 and 2600℃. Experimental results showed that bending strength of the composites was increased up to 1800℃, and they were decreased gradually with increasing annealing temperature of MWCNTs. According to the fracture surface observation, dispersibility of the MWCNTs tended to decrease with increasing the annealing temperature of the MWCNTs, and fracture toughness of the composites corresponded to the dispersibility of the MWCNTs. The present study implies that the effectiveness of the use of MWCNTs having a higher load carrying capacity and dispersibility for preparation of stronger and tougher ceramic composites.
S042013 Fabrication and Evaluation of Carbon Nanotube/Alumina Composites by Pressureless Sintering and Influence of Carbon Nanotube Tensile Strength on Their Composite Mechanical Properties

YAMAMOTO Go, SHIRASU Keiichi, NOZAKA Yo, TAKAGI Toshiyuki, HASHIDA Toshiyuki

Mechanical Engineering Congress, Japan　2012　"S042013-1"-"S042013-5"　2012/09/09
Publisher: The Japan Society of Mechanical Engineers

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In this research, the effects of MWCNT addition on mechanical properties and microstructures of pressureless sintered MWCNT/alumina composites were investigated by using four types of MWCNTs having different fracture characteristics and dispersibility. It was demonstrated that it is possible to fabricate MWCNT/alumina composites by pressureless sintering at a temperature of 1400℃. Fracture tests showed that the MWCNTs annealed at 2200℃ was the most effective in improving the mechanical properties of the MWCNT/alumina composites, and 0.9 vol.% MWCNT addition resulted in 25% and 45% simultaneous increase in bending strength (742.6 ± 13.1 MPa) and fracture toughness (5.83 ± 0.19 MPa m^<1/2>), respectively, compared with MWCNT-free sintered bodies. An improvement in the fracture properties may be attributed to the use of the MWCNT having a higher load carrying capacity. For the larger amount of the MWCNTs, strong correlation between mechanical properties of the composites and dispersibility of the MWCNTs was observed, and the degradation of mechanical properties was shown to be primarily attributed to the severe phase segregation. Our finding suggests that the important factor for the preparation of ceramics composites with MWCNT for higher strength and toughness will thus be the use of MWCNT having a much higher load carrying capacity as well as a good dispersion in the matrix.
Investigation on CNT/alumina interface properties using molecular mechanics simulations (vol 49, pg 3701, 2011)

Sen Liu, Ning Hu, Go Yamamoto, Yindi Cai, Yajun Zhang, Yaolu Liu, Yuan Li, Toshiyuki Hashida, Hisao Fukunaga

CARBON　50　(7)　2677-2677　2012/06

DOI： 10.1016/j.carbon.2012.02.012 　

ISSN： 0008-6223
146 Mechanical Properties of Multi-Walled Carbon Nanotube/Alumina Composites Prepared by Pressureless Sintering

YAMAMOTO Go, SHIRASU Keiichi, NOZAKA Yo, OMORI Mamoru, TAKAGI Toshiyuki, HASHDA Toshiyuki

2012　(47)　98-99　2012/03/13
Publisher: The Japan Society of Mechanical Engineers
215 Development of Fabrication Method of Carbon Nanotube/Alumina Composites and Evaluation of Their Mechanical Properties

SHIRASU Keiichi, YAMAMOTO Go, NOZAKA You, OMORI Mamoru, HASHIDA Toshiyuki

2012　(47)　236-237　2012/03/13
Publisher: The Japan Society of Mechanical Engineers
191 Observation of the Carbon Nanotube/Alumina Composites Fracture Process and Improvement of Their Mechanical Properties

SHIRASU Keiichi, YAMAMOTO Go, OMORI Mamoru, AIZAWA Yoichi, HASHIDA Toshiyuki

2011　(46)　184-185　2011/03/15
Publisher: The Japan Society of Mechanical Engineers
112 Preparation of Carbon Nanotube Reinforced Alumina Composites and Examination of Their Fracture Mechanisms

SHIRASU Keiichi, YAMAMOTO Go, OMORI Mamoru, TAKAGI Toshiyuki, HASHIDA Toshiyuki

Materials and processing conference　2010　(18)　"112-1"-"112-5"　2010/11/27
Publisher: The Japan Society of Mechanical Engineers
007 Evaluation of Crack Bridging Characteristic in Carbon Nanotube/Alumina Composites Using Single Fiber Pullout Testing Method

YAMAMOTO Go, SHIRASU Keiichi, TAKAGI Toshiyuki, HASHIDA Toshiyuki

2010　274-276　2010/10/09
Publisher: The Japan Society of Mechanical Engineers

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The crack bridging behavior of multi-walled carbon nanotube-reinforced alumina matrix composites has been investigated using a single fiber pullout testing method. Contradictory to the conventional understanding (which have reported that pullout phenomena evidently occurred in the bulk nanotube-reinforced alumina composites), the pullout experiments using an in situ SEM method with a nanomanipulator system demonstrated that strong load transfer was revealed, and no pullout behavior was observed for all 15 MWCNTs. The MWCNTs, rather than puffing out from the alumina matrix broke in the outer-shells and the inner section pulled away, leaving the outer-shells of the fragment in the matrix. This implies that tougher ceramics with MWCNT can be obtained by creating the appropriate interaction between the matrix and MWCNT: not too week but also not too strong to permit an adequate load transfer between the two parts and thus a consequent pulling out without breakage of MWCNT. Our finding suggests important implications for design of tougher ceramic with MWCNTs. The important factor for such tougher ceramics will thus be the use of 'strong' NWCNTs having higher mechanical performance (as well as a good dispersion in the matrix).
008 Effect of Surface Modification of Carbon Nanotube on the Strength Properties of Carbon Naotube/Alumina Composites and their Fracture Process

SHIRASU Keiichi, YAMAMOTO Go, OMORI Mamoru, AIZAWA Yoichi, HASHIDA Toshiyuki

2010　271-273　2010/10/09
Publisher: The Japan Society of Mechanical Engineers

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We report the mechanical properties and microstructures of multi-walled carbon nanotube (MWCNT)/alumina composites made with MWCNTs that have nanoscale defects on their surfaces from an acid treatment We conducted the fracture surface observations of the composites, in order to evaluate the effects of the acid treatment conditions of MWCNTs on the mechanical properties of the composites and the microstructures such as dispersibility and pullout length of MWCNTs. It was found that the dispersibiity of MWCNTs affected the mechanical properties of the composites. The composites with 0.9 vol.% MWCNTs that were acid-treated for 2 hours showed a higher mechanical properties than those of the composites with identical MWCNTs content that were acid-treated for 0, 0.5, 1, 3 and 4 hours. According to the SEM observations, the pullout length of MWCNTs decreased with increasing of acid treatment time of MWCNTs, and the diameter changed at the tip of some MWCNTs.
OS0615 A Novel Structure for Carbon Nanotube Reinforced Alumina Composites

Yamamoto Go, Omori Mamoru, Aizawa Yoichi, Hashida Toshiyuki, Takagi Toshiyuki

2009　229-231　2009/07/24
Publisher: The Japan Society of Mechanical Engineers

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We report the mechanical properties of multi-walled carbon nanotube (MWCNT)/alumina composites made with a pristine MWCNT and an acid-treated version that have nanoscale defects on their surfaces from the acid treatment. Microstructural observations revealed that a homogeneous distribution of MWCNTs in the alumina matrix was achieved by a novel processing approach based on the precursor method for the synthesis of alumina and acid-treated MWCNTs. An interesting geometric structure was observed between individual MWCNT and alumina matrix. The nanodefect on the acid-treated MWCNT was filled up with alumina crystal, wiuich may be intruding into the nanodefect during grain growth The addition of only 0.9 voL% acid-treated MWCNTs to alumina resulted in 27% and 25% simultaneous increases in bending strength (689.6 ± 29.1 MPa) and fracture toughness (5.90 ± 0.27 MPam^<1/2>), respectively.
CNT-セラミックス複合材料

山本剛, 大森守, 橋田俊之

工業材料　56　(1)　10-11　2008/01
Publisher: 日刊工業新聞社
カーボンナノチューブを利用したセラミックス基複合材料の製造

山本剛, 大森守, 橋田俊之, 相沢養市, 大久保昭, 木村久道

ケミカルエンジニアリング特集=ライセンス技術の開拓と展望　52　(10)　1-5　2007/10
Publisher: 化学工業社
カーボンナノチューブを利用したセラミックス基複合材料の製造

山本剛, 大森守, 橋田俊之, 相澤養市, 大久保昭, 木村久道

ケミカルエンジニヤリング,（特集ライセンス技術の開拓と展望）　52　(10)　743-747　2007
Publisher: 化学工業社
ISSN： 0387-1037
518 Mechanical Properties of Multi-Walled Carbon Nanotube/SiC Composites Prepared by Direct Thermal Decomposition of Polycarbosilane Precursor

YOKOMIZO Kenji, YAMAMOTO Go, OMORI Mamoru, TAKAHASHI Toru, HASHIDA Toshiyuki

2006　(41)　227-228　2006/03/14
Publisher: The Japan Society of Mechanical Engineers
216 Mechanical Properties of Single-Walled Carbon Nanotube Solids Prepared by Spark Plasm Sintering

YAMAMOTO Go, SATO Yoshinori, TAKAHASHI Toru, OHMORI Mamoru, TOHJI Kazuyuki, HASHIDA Toshiyuki

2004　(39)　76-77　2004/03/13
Publisher: The Japan Society of Mechanical Engineers

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Books and Other Publications 9

空飛ぶクルマ : 空のモビリティ革命に向けた開発最前線

Go Yamamoto

2020/10

ISBN: 9784860436780
実用化に向けたソフトアクチュエータの開発と応用・制御技術

白須圭一, 山本剛, 橋田俊之

シーエムシー出版　2017/03/01

ISBN: 9784781312347
Carbon Nanotubes- Recent Progress

Keiichi Shirasu, Go Yamamoto, Daniel Nelias, Toshiyuki Hashida

InTech　2017
Application of aligned carbon nanotube-reinforced polymer composite to electrothermal actuator

Keiichi Shirasu, Go Yamamoto, Toshiyuki Hashida

InTech　2016
電磁波吸収・シールド材料の設計とノイズ・誤動作対策

山本剛, 白須圭一, 橋田俊之

技術情報協会　2016
高分子における劣化・破壊現象の写真・データ事例集～原因特定と対策のために～

山本剛, 白須圭一, 野坂陽, 橋田俊之

技術情報協会　2014/03/24
カーボンナノチューブ・グラフェン分散技術の工業化と機能展開 – 溶液・ポリマー・金属・セラミックスへの分散 –

山本剛, 白須圭一, 野坂陽, Weili Wang, 橋田俊之

S&T出版株式会社　2014/02/26

ISBN: 9784907002343
【エレクトロニクス用途における】コンポジット材料の混練・コンパウンド技術と分散・界面制御

山本剛, 白須圭一, 橋田俊之

技術情報協会　2013/04/26

ISBN: 9784861044779
Composites and Their Properties

Go Yamamoto, Toshiyuki Hashida

InTech　2012/08/22

ISBN: 9789535107118

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Research Projects 9

Multiscale Mechanics of MWCNT Reinforced Composite Materials

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2022/04/01 - 2025/03/31
Development for polymer matrix selection guide for carbon fiber reinforced plastic composites

Yamamoto Go

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2018/04/01 - 2021/03/31

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The tensile strength-controlling factors of unidirectional carbon fiber reinforced plastics (CFRP) composites were investigated focusing on assessing the mechanical properties of the epoxy matrix. The degree of concentrated stress acting on the intact fiber surface, which determines the tensile strength properties of unidirectional CFRP composites, was evaluated by implementing double-fiber fragmentation tests in conjunction with numerical simulations. Correlation analysis was conducted, with the aim of extracting the factors that characterize the tensile strength of the unidirectional CFRP composites. The analysis of six epoxy materials with different mechanical properties demonstrated that the matrix crack tip displacement (CTOD) exhibited a linear correlations with surface stress concentration factor (SCF). These results revealed that CTOD is one of the dominant factors influencing the tensile strength characteristics of unidirectional CFRP composites.
Preparation of Novel Silicon Nitride Ceramics Using Non-oxide Sintering Agents and Their Applications for Structural/Functional Materials

Hashida Toshiyuki

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2016/04/01 - 2019/03/31

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The use of non-oxide sintering agents was investigated to prepare silicon nitride ceramics with enhanced high-temperature properties. A non-oxide sintering agent containing yttrium was selected and silicon nitride samples were successfully sintered with a full density utilizing the agent. Three-point bending tests conducted at argon gas environment revealed that the silicon nitride prepared with the non-oxide sintering agent maintained higher flexural strength at high temperatures compared with that for an oxide sintering agent, yttria. The phases of the non-oxide, and oxide sintering agents in the sintered condition were shown to be crystal and amorphous, respectively. The crystal phase may be a plausible reason for the improved high-temperature strength in the non-oxide sintering. Furthermore, the addition of the non-oxide agent caused no deterioration in the thermal conductivity measured with a laser flash method, and led to excellent tribological characteristics in water.
Structural modification of multi-walled carbon nanotube: Is multi-walled carbon nanotube acceptable as a reinforcing agent in fiber-reinforced composites?

Yamamoto Go

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Young Scientists (A)

Institution: Tohoku University

2015/04/01 - 2018/03/31

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It was revealed that by introducing the Frenkel pair type crosslinking between MWCNT layers, the tensile load applied to the outermost layer was effectively transferred to the inner CNT layers. Furthermore, introduction of such crosslinking led to the improvement in the nominal strength and the defect sensitivity. Structural defects which induced the failure of the MWCNTs were clarified through tensile-loading experiments of the individual MWCNTs with the aid of TEM observations. The structural changes observed after high temperature annealing led to modest impact on the nominal tensile strength of the MWCNTs, which was mainly attributable to incomplete removal of the structural defects by thermal annealing. For the composites made with epoxy polymer, it was theoretically shown that a main crack accompanied by the MWCNT pullout took place due to the lower interfacial sliding resistance prior to multiple failures of the MWCNT occurred.
Development of novel electromagnetic absorbers - Effects of MWCNT diameter and dispersion state of MWCNT -

Yamamoto Go

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Exploratory Research

Institution: Tohoku University

2014/04/01 - 2016/03/31

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Microstructure-property relationships MWCNT/alumina composites have been investigated using two types of MWCNTs having different diameters as well as almost the same crystallinity and length; the influences of MWCNT diameter and dispersion states of MWCNTs on the electromagnetic absorption properties of the composites have been explored. It has been found that the composites made with MWCNT having a larger dimeter showed higher electromagnetic absorption properties compared to the small-diameter MWCNT/alumina composites. However the differences in the diameter of MWCNTs lead to no significant impact on peak absorption frequencies. It has been also shown that differences in the dispersion states of the MWCNT in the alumina matrix lead to a significant impact on the electromagnetic absorption properties of the composites. The resulting MWCNT/alumina composite with a MWCNT aggregate were founded to demonstrate effective microwave absorption in the investigated region.
Development of novel electromagnetic absorbers using carbon nanotube/alumina composites

YAMAMOTO Go

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Exploratory Research

Institution: Tohoku University

2012/04/01 - 2014/03/31

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Electromagnetic absorption properties of pressureless-sintered multi-walled carbon nanotube (MWCNT)/alumina composites have been investigated using four types of MWCNTs having different crystallinity as well as diameter and length; the influence of crystallinity, diameter and length on the composites' electromagnetic absorption properties have been explored. It has been found that the composites containing the MWCNT annealed at 2873 K with higher degree of crystallinity showed higher electromagnetic absorption properties compared to other types of MWCNTs as well as alumina alone. It has been also shown that differences in the diameter and length of the MWCNTs lead to no significant impact on the electromagnetic absorption properties of the composites.
Development of Design-Fabrication-Evaluation Methodology for High Performance Composites Reinforced by Carbon Nanotube

HASHIDA Toshiyuki, TOHJI Kazuyuki, TAKAGI Toshiyuki, ONO Takahito, FU Ning, OMORI Mamoru, YAMAMOTO Go

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (S)

Institution: Tohoku University

2009/05/11 - 2014/03/31

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Preparation and evaluation of multi-walled carbon nanotube (MWCNT) reinforced alumina composites were conducted with the objective of promoting practical applications of engineered ceramic composites. Uniform dispersion of MWCNTs in matrix precursors was achieved primarily by controlling the rigidity of the MWCNTs used and through their surface modifications. Furthermore, in view of the advantage for industrial applications, a pressureless sintering method was developed in contrast with the pressure-assisted techniques used in the previous studies. The achievements then enabled us to successfully produce homogeneous MWCNT/alumina composites with the highest strength and fracture toughness compared with the literature data. It was demonstrated that the MWCNT/alumina composites developed in this study had superior friction/wear properties, electric conductivity, and electric magnetic wave absorption characteristics, providing a useful foundation for their practical applications.
ナノスケール構造制御による高機能CNT／セラミックス複合材料の実用化手法開発

山本剛

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 研究活動スタート支援

Institution: 東北大学

2011/08/24 - 2013/03/31

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セラミックスはその優れた材料特性から,機器・構造材料の性能や適応範囲の壁をブレークスルーできる可能性を有している.しかしながら,き裂先端での高い応力集中を緩和させる機構が作用しにくいセラミックス材料は脆く,これを機器・構造用部材の荷重担体として安全に使用できる段階まで開発されてはいない.本研究の目標は,カーボンナノチューブの優れた材料特性を活用することで,実用化可能な多機能性セラミックスの創製のための設計手法の方法論を構築することである.研究目標を達成するための最も重要な課題は,"破壊靭性の飛躍的な向上"と"連続生産が可能な製造プロセスの確立"である. 開発材料の破壊特性の向上牽達成するためには荷重担体となる繊維の破壊強度に関する理解は,繊維を強化要素として使用した複合材料の設計において極めて重要である.このような背景のもと,今年度は,異なる温度でアニール処理を行った4種類のMWCNT単味の一軸引張実験をSEM観察下において実施した.その結果,MWCNTのナノ構造に依存して剣鞘型あるいはクリーンブレーク型の破断形態を呈することを見出すとともに,MWCNT単味の破壊特性を向上させるための最適なナノ構造が存在することを発見した.さらに,アニール処理によりナノ組織を制御でき,MWCNT単味の強度を向上できることを世界に先駆けて示している.従来のMWCNT/セラミックス複合材料の作製に関する研究では,放電プラズマ焼結法等のバッチ式加圧焼結法が多用されてきた.無加圧焼結法によることができれば,サンプルの大型化や任意形状の部品への展開など,実用上の利点が期待される.本研究では,無加圧焼結法で緻密なMWCNT/アルミナ複合材料を作製することに成功し,試作材の強度および破壊靱性特性はバッチ式加圧焼結法も超える世界トップの値であることを示している.この成果は,複合体作製の連続プロセス化を可能にするものであり実用化を大きく前進させることが期待される.
炭素ナノ材料を用いた革新的シナジーセラミックス創製法の開発

山本剛

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(B)

Institution: 東北大学

2007 - 2009

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本研究において申請者が期間内に達成する課題は、靭性、摩擦・摩耗特性の観点から、既存のセラミックス材料の材料特性を凌駕するセラミックス/カーボンナノチューブ複合材料を合成することである。研究の初年度にあたる今年度は、前駆体法を用いた複合材料の合成とその力学的特性評価を実施した。具体的には、特性・機能の発現を可能とする材料合成技術の確立を図るとともに、開発材料の基礎力学特性を評価することで合成技術の有効性を検討した。申請者らはこれまでに、アルミナセラミックス中にカーボンナノチューブ(CNTs)が真に単離分散した組織を有する複合材料の作製に成功している。しかしながら、その破面からはCNTsとアルミナセラミックスとの界面強度の低さに由来する顕著なCNTsの引抜け挙動が認められている。従い、CNTsの有する材料ポテンシャルを充分に開発材料へ反映させるために、CNTsとアルミナセラミックスとの界面強度を増大させる必要がある。 CNTsとアルミナセラミックスとの界面強度の増大を目的とし、混酸を用いたCNTsの湿式酸化処理を行った。その結果、処理条件の最適化を図ることによりCNT表面にナノ寸法を有する欠陥を導入することに成功した。CNT充填量の曲げ強度および破壊靱性特性に及ぼす影響評価を行い、湿式酸化処理を施したCNTsを出発原料に使用した複合体はCNTsを0.5mass%添加した際に最も複合効果が得られ、複合体の曲げ強度(σ_b)ならびに破壊靱性値(K_<Ic>)はそれぞれ689.6±29.1MPaと5.90±0.27MPa・m^<1/2>であった.これらの値は既成のアルミナセラミックス(σ_b:380MPa,K_<Ic>:1〜3MPa・m^<1/2>)と比べ大きく、力学的特性の向上が達成された。 CNTを活用した材料開発に関する研究は世界的規模で活発に行われているものの、その主要な研究・開発の内容は単一特性の向上を目指したものであり、複数の特性や機能の付与に関する研究は世界的にも前例は見受けられない。このような現状に対して、シナジー効果の発現を可能とする材料合成技術、さらには実用化を踏まえた材料合成プロセスに関する研究は、本研究がはじめて開拓するものである。

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Social Activities 3

出前講義「福島県立安積黎明高等学校」

2018/07/04 - 2018/07/04
第23回科学講演会「親子のためのロケット公開教室」

2016/08/28 -

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一般市民、特に小中学生に実技を通して航空宇宙に関する興味と科学技術に関する関心を持っていただくことを目的に、「軌道エレベーターで宇宙に行こう！」のタイトルで講演を行った。
CNTs reinforce alumina composites

2008/07 -

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ｔｂｃ東北放送「エンボヤージュ」出演

ｔｂｃ東北放送　ｔｂｃ東北放送

2022/07/21

Type: TV or radio program
A novel structure for carbon nanotube reinforced alumina composites

2008/07

Type: Other

Other 1

カーボンナノチューブを用いた電磁波吸収体の創製

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キラル物質は、電磁波の偏波面を回転させる特性を有しており、入射した直線偏波の電磁波はキラル物質内で左・右旋回の二つの円偏波に分離されて再放射される。この効果により、構造体内に分散したキラル物質が電磁波を吸収・散乱しながら熱エネルギーに変換させる。本研究の目的は、カーボンナノチューブのナノキラル構造に着目し、異なる3つの学問 (材料強度学・電気化学・材料科学工学) を専門とする3名の研究者が研究グループを構成することで、MWCNT を用いた新しい電磁波吸収材料を創製することである。