研究者詳細 - 高橋　拓実

論文 - 高橋　拓実

件数 19 件

Effects of rare-earth oxides on grain boundary strength of silicon nitride ceramics

K. Matsuura, T, Ohji, T. Takahashi, M. Iijima, J. Tatami

Journal of the European Ceramic Society 44 ( 14 ) 116672 2024年6月 [査読有り]

記述言語：英語掲載種別：研究論文（学術雑誌）単著

Deformation Behavior and Fracture Strength of Single‐Crystal 4H‐SiC Determined by Microcantilever Bending Tests

Tsukaho Yahagi, Tatsuki Ohji, Hiroshi Yamaguchi, Takuma Takahashi, Hiromi Nakano, Motoyuki Iijima, … 全著者表示

Advanced Engineering Materials 2024年5月 [査読有り]

DOI

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Scintillation properties of transparent Lu-α-SiAlON:Ce3+ ceramics

Aminaka, K; Tatami, J; Iijima, M; Ito, A; Matsumoto, S; Takahashi, T; Ohji, T

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY 21 ( 4 ) 2671 - 2677 2024年4月

DOI Web of Science

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Deformation behavior and bending strength of single crystal 8 mol% yttria-stabilized zirconia at microscopic scale

Mayuko Muramoto, Junichi Tatami, Motoyuki Iijima, Kazumi Matsui, Tsukaho Yahagi, Takuma Takahashi, … 全著者表示

Journal of the European Ceramic Society ( 2 ) 1061 2024年2月 [査読有り]

DOI

記述言語：英語掲載種別：研究論文（学術雑誌）共著

アルミナ成形体の脱脂挙動におよぼす無機バインダーの影響

南真利子, 多々見純一, 飯島志行, 高橋拓実

粉体工学会誌 60 ( 9 ) 542 - 546 2023年9月 [査読有り]

DOI CiNii Research

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人粉体工学会共著

The internal structure of Al2O3 green bodies during dewaxing process was directly observed by optical coherence tomography. The gas generation during dewaxing and the mechanical property of green bodies at high temperatures were further analyzed by TG and three-point bending test, respectively. Although crack formation was observed during the dewaxing process in the green body prepared by adding only PVB as an organic binder, no cracks were found in the green body prepared by simultaneous addition of PVB and basic aluminum lactate, which was an inorganic binder. Simultaneous addition of organic and inorganic binders improved the bending strength of the green bodies due to the presence of inorganic link among the particles, which prevented the green bodies from cracking. Inorganic binder was effective to control crack-formation in the green body.

OCTオペランド観測による粒子懸濁液の乾燥過程の解明

髙橋拓実

ホソカワ粉体工学振興財団年報 30 ( 0 ) 65 - 71 2023年5月

DOI CiNii Research

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：公益財団法人ホソカワ粉体工学振興財団単著

粒子懸濁液を扱う製品や材料の製造プロセスにおいて，乾燥時に形成される粒子集合構造は最終的な性能と密接に関係するため，的確かつ自在な制御が強く望まれている．しかし，多様な因子が相互に影響する複雑さから，実環境下での現象の直接的な理解は困難であった．本課題を解決するべく，材料の乾燥特性の標準的スケールである乾燥特性曲線の測定と内部構造変化の観察を同時に行うことができるオペランド観測システムを本研究で構築した．システムは観察用の波長掃引型光コヒーレンストモグラフィー（SS-OCT）と，重量変化を測定する電子天秤，環境の温湿度変化を測定するプローブで構成された．本システムでコーヒーの液滴やAl2O3スラリーの乾燥挙動を観測し，乾燥中の内部構造変化と乾燥特性とを直接相関させ，定量的な評価ができることを明らかにした．さらに，Al2O3スラリーの固体濃度や粒子の分散凝集が内部構造変化や乾燥特性に及ぼす影響も明らかにした．

In-situ investigation on crack-initiation and deformation of Al2O3 green bodies during dewaxing process by combined OCT-TG-FTIR and TMA

Minami Mariko, Tatami Junichi, Iijima Motoyuki, Takahashi Takuma, Ohji Tatsuki

CERAMICS INTERNATIONAL 49 ( 10 ) 15387 - 15394 2023年5月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

Deformation behaviors and fracture strength of β-Si3N4 single crystals

Mami Tanabe, Junichi Tatami, Motoyuki Iijima, Tsukaho Yahagi, Takuma Takahashi, Hiromi Nakano, Tats … 全著者表示

Journal of the American Ceramic Society 106 ( 9 ) 5431 - 5439 2023年4月 [査読有り]

DOI

記述言語：英語掲載種別：研究論文（学術雑誌）共著

Novel operando observation technique based on combined optical coherence tomography–thermogravimetry for monitoring internal structural changes of drying ceramic slurries

Kuroda Hiromasa, Tatami Junichi, Iijima Motoyuki, Takahashi Takuma

大日本窯業協會雑誌 131 ( 3 ) 37 - 41 2023年3月 [査読有り]

DOI Web of Science CiNii Research

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人日本セラミックス協会共著

In the wet forming of ceramics, it is critical to control the cracking and deformation of the ceramic slurry during the drying process. This necessitates a comprehensive understanding of the changes in the internal structure of the slurry during the drying process using a high-resolution technique that enables direct and high speed observation. In this study, a combined system of optical coherence tomography (OCT) and thermogravimetry (TG) was developed for the operando observation of the evolution of the internal structure of a drying SiO2 slurry. In the early stages of drying, the OCT signal intensity changed significantly owing to the Brownian motion of the SiO2 particles in the slurry. The slurry was found to shrink as it dried and then lose its fluidity, and the ceramic particles were found to agglomerate from the surface. In the final stages of drying, localized dry regions developed in the vicinity of the slurry surface and expanded with drying. Crack formation was also observed in a part of the localized dry regions. Therefore, crack formation was attributed to inhomogeneous drying-induced shrinkage and stress generated in the drying object during the progression of localized drying. The novel operando observation technique using combined OCT-TG is successfully demonstrated to be an effective approach for understanding the internal structural changes in opaque slurries during their drying.

Effect of rare-earth oxide additives on transparency and fluorescence of a-SiAlON ceramics

Aminaka Kohei, Tatami Junichi, Iijima Motoyuki, Takahashi Takuma, Yahagi Tsukaho

CERAMICS INTERNATIONAL 48 ( 16 ) 23195 - 23205 2022年8月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

Transparency and Photoluminescence of Gas-Pressure Sintered Lu-alpha-SiAlON:Ce3+ Ceramics

Aminaka Kohei, Tatami Junichi, Iijima Motoyuki, Takahashi Takuma

ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY 11 ( 7 ) 2022年7月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

In situ observation of evolution of internal structure of alumina during sintering by swept-source OCT

Takahashi Takuma, Sakamoto Fumika, Tatami Junichi, Iijima Motoyuki

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY 19 ( 2 ) 1171 - 1179 2022年3月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

Electrical resistivity of Si3N4 ceramics with Yb2O3 additive

Yahagi Tsukaho, Kawai Daisuke, Takahashi Takuma, Iijima Motoyuki, Tatami Junichi

JOURNAL OF THE AMERICAN CERAMIC SOCIETY 105 ( 3 ) 2046 - 2057 2022年3月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

Transparent Y-alpha SiAlON:Ce3+ Ceramics Fabricated by Low-Temperature Liquid Phase Sintering Technique

Takahashi Takuma, Sano Yuki, Tatami Junichi, Iijima Motoyuki, Yokouchi Masahiro

ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY 10 ( 8 ) 2021年8月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

Room-temperature densification of MgO bulk ceramics with dispersed nitride phosphor particles

Takahashi Emi, Takahashi Takuma, Tatami Junichi

CERAMICS INTERNATIONAL 47 ( 4 ) 5013 - 5018 2021年2月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

光コヒーレンストモグラフィーによるAl2O3顆粒の一軸加圧下における粉体層中の空隙の形態変化過程のその場観察

高橋拓実, 多々見純一

粉体および粉末冶金 67 ( 11 ) 615 - 620 2020年11月 [査読有り]

DOI CiNii Research

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人粉体粉末冶金協会共著

Uniaxial pressing is a utilized technique to prepare powder compacts in regions of ceramics, metal, drug, and functional food. On the other hand, it is known that the inhomogeneous structures are induced by stress distribution resulting from applying the anisotropic stress field to the powder bed and they become the origin which forms defect degrading the performance of products. However, the generation process of inhomogeneous structures has not been clarified experimentally. Directly understanding the formation mechanism of the internal structure during uniaxial pressing is very important to control the particle-assembled structure in the powder bed and the quality of products. In this work, the change process in void morphology under uniaxial pressing was observed dynamic-two-dimensionally and intermittent-three-dimensionally by the novel observation system composed of swept-source optical coherence tomography (SS-OCT) and material testing machine. Moreover, the detected voids were evaluated quantitively to directly clarify particle-packing behavior on the initial stage of pressing.

Relationship between bending strength of bulk porous silicon carbide ceramics and grain boundary strength measured using microcantilever beam specimens

Tatami Junichi, Imoto Yumi, Yahagi Tsukaho, Takahashi Takuma, Iijima Motoyuki

JOURNAL OF THE EUROPEAN CERAMIC SOCIETY 40 ( 7 ) 2634 - 2641 2020年7月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

Dislocation-controlled microscopic mechanical phenomena in single crystal silicon under bending stress at room temperature

Yamaguchi Hiroshi, Tatami Junichi, Yahagi Tsukaho, Nakano Hiromi, Iijima Motoyuki, Takahashi Takuma … 全著者表示

JOURNAL OF MATERIALS SCIENCE 55 ( 17 ) 7359 - 7372 2020年6月 [査読有り]

DOI Web of Science

記述言語：日本語掲載種別：研究論文（学術雑誌）共著

窒化物蛍光体粒子分散h-BN／ガラス複合体の作製

虎瀬なつみ, 多々見純一, 飯島志行, 高橋拓実

粉体工学会誌 57 ( 3 ) 137 - 143 2020年3月

DOI CiNii Research

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人粉体工学会共著

Wavelength conversion materials with high thermal conductivity and heat resistance have been strongly desired for high power semiconductor lighting source. Glass has higher heat resistances at elevated temperatures than resin and dispersion of high thermal conductive particles should result in the improvement of thermal conductivity of the composites. In this study, the composites of phosphate glass dispersing nitride phosphor and high thermal conductive particles were fabricated instead of typical composites of resins and oxide phosphors. As a result of verification of reactivity of the nitride phosphor and the high thermal conductive particles with the phosphate glass, between the glass and fillers, the firing temperature was set to 500°C and h-BN particles were selected as high thermal conductive particles. Dense nitride phosphor particles dispersed h-BN/glass composites were successfully obtained by hot-pressing. Thermal conductivity normal to hot-pressing direction was higher than that parallel to hot-pressing direction, and it increased with an increase in the hot-pressing pressure and the quantity of dispersed h-BN particles because of higher density and better orientation of the h-BN particles. Consequently, the nitride phosphor particle dispersed h-BN/glass composites with the thermal conductivity of 9.4 W/(m−1·K−1) were obtained.

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論文 - 高橋　拓実