持続可能で、安全・安心な社会の実現に向けて、鉄道、産業機器、エネルギー機器をはじめとした様々な分野の省エネ化、高安全化、循環化を実現するための、製品性能を革新する最先端材料やプロセスならびにマルチフィジックス設計に関する研究開発
（最先端製品向けのマテリアルズインフォマティクスを活用した有機・高分子・金属・無機・磁性・複合材料等の最先端材料技術に関する研究開発およびモノづくりの自動化、省エネ化、CO2排出削減に向けたデジタル製造技術、材料プロセス技術、光学・熱設計技術およびデジタル技術）
有機・高分子・金属・無機・磁性・複合材材料等の最先端材料、高信頼化技術、プロセス技術、マテリアルズインフォマティクス（材料シミュレーション、プロセスシミュレーション）、モノづくりDX化技術（材料プロセスナレッジとデジタル技術の両方を用いた開発）、光学・熱設計技術
Publishing Academic Papers:
Shinya Tamura, Tomonori Kimura, Yasuhisa Aono
Metals 15, 1208 (2025)
Effect of ω-Phase Precipitation on Magnetic Susceptibility and Corrosion Resistance of Meta-Stable β-Phase Zr-Nb-Ti-Cr Alloy
Abstract: As well as having corrosion resistance and mechanical properties, medical metallic biomaterials used in metal implants must allow imaging by MRI for prognostic diagnosis. Alloys based on Ti, Fe, Co, etc., have the disadvantage that those constituent elements have higher magnetic susceptibility than the tissue surrounding the metallic implant, and this condition results in defects and distortions ("artifacts") in MR images during MRI imaging. In consideration of this issue, MRI-compatible low-magnetic-susceptibility materials are currently being researched and developed. In this study, microstructural control of Zr-based alloys by alloy design and heat treatment was investigated. The problem with pure Zr is its low corrosion resistance due to the α-phase of its hexagonal-close-packed (HCP) structure. However, alloys that were alloyed and solution heat-treated to a β-phase (body-centered cubic (BCC) structure) showed high corrosion resistance. In particular, when Zr-15Nb-5Ti-3Cr, which has relatively high corrosion resistance, was subjected to aging heat treatment at 673 K for 1.8 ks, precipitation of fine ω-phase in the β-phase was confirmed. The metallographic structure in which the ω-phase precipitated in the β-phase provided high corrosion resistance [≧1000 mV (vs. SHE)] derived from the β-phase, as well as low magnetic susceptibility (approximately 1.2 × 10−6 cm3/g), due to the effect of the ω-phase. This study provides guidelines for microstructural control to achieve both low magnetic susceptibility and high corrosion resistance in Zr-based metallic biomaterials for medical use.
Hayate Saito, Hironori Shinmori, Qian Chen, Ryosuke Hori, Takehiro Morita, Yoshio Kobayashi, Yoshinori Sawae
Tribology International 212, 110963 (2025)
Effect of sliding paths on wear and friction of polytetrafluoroethylene composites
Abstract: Understanding the effect of sliding paths on the tribological properties of sliding materials is crucial for the design of industrial equipment, but remains poorly understood. In this study, the tribological properties of multi-filler polytetrafluoroethylene (PTFE) composites were investigated under two different sliding paths (linear reciprocating motion with unidirectional sliding and circular motion with multidirectional sliding) to elucidate their effect on the friction and wear of PTFE composites. Under linear reciprocating motion at room temperature and 120°C, it was observed that carbon fibers aligned in the sliding direction and formed carbon stripes which support the contact load and effectively reduced wear. Circular motion at room temperature showed reduced wear due to the formation of a carbon-based tribofilm on the surface of PTFE composites. When subjected to circular motion at 120°C, the tribofilm exhibited peeling and internal cracking, leaving the PTFE matrix unprotected and leading to a significant increase in wear by one to two orders of magnitude compared with the other conditions. Under linear reciprocating motion at 120°C, the amounts of tribofilm on the surface of the PTFE composites and the transfer film on the sliding mating surface were found to be smaller than under other conditions, indicating insufficient carbon-derived lubricity. Consequently, the friction under linear reciprocating motion at 120°C was higher compared with the other conditions. As described above, the effect of sliding paths on the friction and wear of PTFE composites was clarified.
Hitomi Takahashi, Shogo Arata, Satoyuki Nomura
Tribology Online 20, 179 (2025)
Abstract: Atomistic Insights into the Copper Oxidation Reactions for the CeO2-Cu Interface Using First-Principles Molecular Dynamics Simulations
The reaction pathways of Cu oxidation by the chemical mechanical polishing (CMP) slurry containing ceria (CeO₂) abrasive grains were theoretically investigated. First-principles molecular dynamics (FPMD) simulations were employed to analyze the reaction pathways between a CeO₂ surface and a Cu surface. As a result, the following reactions were observed: chemical bonds between CeO₂ and Cu were formed, electron transfer from Cu atoms to Ce atoms occurred, a water molecule dissociated on the CeO₂ surface to form a proton and an OH⁻ ion, and the generated OH⁻ ion formed Cu-O bonds with the oxidized Cu atoms. The candidate reaction pathways for Cu oxidation, including those observed in FPMD simulations, were further analyzed by constructing energy diagrams using density functional theory (DFT) calculations. As a result, the reaction pathway observed in the FPMD simulation was identified as the most likely candidate, having the lowest activation energy and the lowest final structure energy. These results indicate that the oxidation reaction pathways of Cu in the slurry containing CeO₂ abrasive grains involve electron transfer through the formation of chemical bonds between CeO₂ and Cu, as well as the supply of oxygen atoms derived from water to Cu atoms.
Atsushi Iijima, Hitomi Takahashi, Hayate Saito, Hiroshi Kanetomo
IEEE Transactions on Dielectrics and Electrical Insulation 32, 1975 (2025)
Effect of Additives on Durability of Insulating Paper in Natural Ester Oil
Abstract: The life of insulating paper is key to transformer reliability and service life. For transformers using natural ester oil, the effect of a surface protection layer is examined to suppress the degradation of insulating paper that occurs when moisture is continuously taken up. From first-principles calculations, carboxy and amide groups are extracted as functional groups with a high adsorption energy to the insulating paper surface. Adsorption experiments using additives with those functional groups are performed, and Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and contact angle measurements suggest that stearic acid has a strong ability to form a surface protective layer. Accelerated degradation tests using stearic acid as an additive show that the residual tensile strength after 25 h at 170 °C is significantly higher than that of without additive, verifying the idea that forming a surface protective layer extends the life of insulating paper.
Tomohiro Tabata, Matahiro Komuro, Yusuke Asari, Shinya Tamura, Masafumi Nojima, Tomio Iwasaki, Shohei Terada
AIP Advances 14, 065217 (2024)
Challenge of fabricating difficult-to-nitride materials: Formation of martensitic phase in (Fe0.8Co0.2)8N foil based on industrially suitable gas-nitriding process
Abstract: Nitrogen-martensitic phase (Fe0.8Co0.2)8N was successfully synthesized by using an industrially suitable gas-nitriding process of a bulk foil. So far, the nitrogen-martensitic phase of the bulk material has not been synthesized at such a high Co content. We found that this is because the nitride was easily denitrided by elevating temperature. In this work, by exploiting a NH3 gas-nitriding process combined with quenching at a rapid cooling rate (>800 °C/s) in NH3 atmosphere, we found that nitrogen stayed at the surface layer of the foil. By using cross-sectional laser microscopy, the nitride region was observed as a 7-μm-thick layered shape at the surface of the 100-μm-thick foil. An x-ray diffraction technique revealed that the nitride layer was a martensitic phase that was characterized as a body-centered tetragonal structure with c/a = 1.04. These findings can be applied to nitriding and surface treatments for alloy systems in which a nitrogen solid solution is hardly formed. Our developed method is promising because the martensitic phase is expected to be formed in whole bulk by further optimizing parameters clarified in this work.
Satoshi Ishii, Hitomi Takahashi and Yoshie Sakai
Smart Materials and Structures 33, 125017 (2024)
Viscoelastic properties of electro-rheological fluids containing ion-conductive polyurethane particles under electric field
Abstract: A non-hydrous electro-rheological fluid (ERF) containing polyurethane (PU) particles with electrolytes and automotive dampers utilizing it have been developed. In this study, we investigated the influence of electrolytes and particle properties on ER effect (yield stress) leading to improving the ER effect of non-hydrous ERFs. As a result, yield stress was increased by the inclusion of electrolytes to PU particles and decreased by increasing the glass transition point (Tg) of PU. The inclusion of electrolyte in particles doubled the yield stress of ERF at 5 kV mm-1. The change in Tg of PU particles from -26.3 °C to -15.3 °C resulted in a decrease in yield stress by 0.7 times at 5 kV mm-1. According to a theoretical model for calculating the ER effect and experimental data, the ionic conductivity associated with the electrolyte addition and the Tg change contributed to the dielectric constant of the PU particles, which affected the ER effect. This result provides important knowledge for deriving material compositions that can further improve the ER effect.
Hitomi Takahashi and Satoyuki Nomura
Tribology Online 19, 208 (2024)
Effects of Hydrogen Peroxide on Chemical Mechanical Polishing of Copper Surface:
Exploration of Reaction Pathways with Molecular Dynamics Simulation and Activation
Energies Calculation
Abstract:The mechanisms of chemical mechanical polishing (CMP) of copper (Cu) surface using a slurry containing hydrogen peroxide (H2O2) and silica abrasive grains were theoretically investigated. First, molecular dynamics (MD) simulations using ReaxFF were used to analyze reactions that remove Cu atoms from the Cu(111) surface. At the Cu/H2O2 interface, Cu atoms were oxidized by forming Cu-O bonds with O atoms derived from H2O2 or H2O. The behavior of the oxidized Cu atoms depended on the surrounding environment. Following two types of reaction pathways for the removal of oxidized Cu atoms were found. In the first pathway, neighboring Cu atoms were oxidized. In the second pathway, the atomic arrangement around the oxidized Cu atoms was disordered caused by surface vacancies. In relation to the first reaction pathway, activation energies were calculated to study the effects of the oxidation of Cu atoms on the Cu removal reactions. The results showed that the lowest activation energy was obtained when the structure in which neighboring Cu atoms were most oxidized, which supported the results of the MD simulations. The findings of this study indicate that
the oxidation degree of adjacent Cu atoms and the atomic arrangement of the Cu surface affect the Cu removal reactions.
Yusuke Hibi, Yasuhiro Tsuyuki, Satoshi Ishii, Eiichi Ide, Masanobu Naito
Science and Technology of Advanced Materials 25, 1 (2024)
Decoding Thermal Properties in Polymer-Inorganic Heat Dissipators: A Data-Driven Approach Using Pyrolysis Mass Spectrometry
Abstract: Polymeric materials can boost their performances by strategically incorporating inorganic substances. Heat dissipators are a representative class of such composite materials, where inorganic fillers and matrix polymers contribute to high thermal conductivity and strong adhesion, respectively, resulting in excellent heat dissipation performance. However, due to the complex interaction between fillers and polymers, even slight differences in structural parameters, e.g., dispersion/aggregation degree of fillers and crosslink density of polymers, may significantly impact material performance, complicating the quality management and guidelines for material developments. Therefore, we introduce pyrolysis mass spectra (MS) as material descriptors. On the basis of these spectra, we construct prediction models using a data-driven approach, specifically focusing on thermal conductivity and adhesion, which are key indicators for heat dissipating performance. Pyrolysis-MS observes thermally decomposable polymers, which occupy only 0.1 volume fraction of the heat dissipators; nevertheless, the physical states of non-decomposable inorganic fillers are implicitly reflected in the pyrolyzed fragment patterns of the matrix polymers. Consequently, pyrolysis-MS provides sufficient information to construct accurate models for predicting heat dissipation performance, simplifying quality management by substituting time-consuming performance evaluations with rapid pyrolysis-MS measurements. Furthermore, we elucidate that higher crosslinking density of the matrix polymers enhances thermal conductivity. This data-driven method promises to streamline the identification of key functional factors in complex composite materials.
Hayate Saito , Masahiro Ito, Katsumi Mabuchi
CORROSION 79, 1267 (2023)
Empirical Model for Predicting Corrosion Under Insulation Considering the Effects of Temperature, Salinity, and Water Content
Abstract: Corrosion under insulation (CUI) is one of the increasing issues in industries such as oil refineries and petrochemical plants. For preventing accident and reducing the inspection load caused by CUI, the prediction model for CUI has attracted increasing attention. In this study, to construct a prediction model for the corrosion rate of CUI (CUI rate), the effects of water content in the insulation material, salinity, and temperature on the CUI rate were evaluated with a corrosion test simulating a CUI environment. Analysis of the atmospheric corrosion monitoring sensor current showed that the CUI rate increased as the water content increased, promoting the formation of the water-thin film at the interface of insulation and carbon steel. Maxima of the CUI rate were observed for salinity and temperature. Salinity increased the electrical conductivity of the water-thin film and promoted the corrosion reaction, and over a certain salinity, the water-thin film became thicker and the CUI rate decreased due to the rate-determining step in oxygen diffusion. Over a certain temperature, the CUI rate decreased due to the evaporation of the water-thin film and a decrease in dissolved oxygen. We constructed the prediction model for the CUI rate with a coefficient of determination of 0.87 by multiple regression analysis using the obtained test data.
2025年度 第39回エレクトロニクス実装学会 春季公演大会 ポスターアワード
「公開データに基づいたMIと分子シミュレーションによる界面密着強度向上設計」
2025年度 日本機械学会茨城ブロック貢献賞
「日本機械学会茨城ブロックの活動への貢献」
2024年度 日本溶接協会 技術賞(本賞)
「製造業の溶接技能者不足を解消する技能教育システムの開発と原子カプラントの配管溶接への適用」
2024年度 日本材料学会 技術賞
「公開データに基づいた Chemicals Informatics ツールによる材料探索技術」
2024年度 第33回 ポリマー材料フォーラム 優秀発表賞
「金属酸化物を用いた低温熱分解によるFRPの繊維リサイクル」
2023年度 溶接接合工学振興会 金澤賞
「高精度動作センシングによる溶接技能 のデジタル化と溶接士技能を搭載した 溶接自動化技術の開発」
2023年度 エレクトロニクス実装学会 マイスター賞
「プリント配線基板表面処理技術および低環境負荷めっき技術の開発」
2023年度 第37回春季講演大会 ポスターアワード賞
「動的共有結合樹脂を適用した再成形可能なFRP」
2022 年度溶接学会 ベストオーサー賞
「最新の溶接技能伝承 高精度動作センシングによる溶接技能デジタル化と溶接士技能を搭載した溶接自動化」
2022年度 第31回ポリマー材料フォーラム 広報委員会パブリシティ賞
「公開データから探索したバイオ由来ポリ乳酸樹脂用添加剤の効果実証」
2021年度 日本溶接協会 技術賞
「自動車燃料系部品へのレーザ溶接溶込み深さ 全数検査技術の適用」
2020年度 日本機械学会 材料力学部門 業績賞
「電子デバイスを高信頼化させる原子レベル材料設計に関する先駆的研究」
QRコードラベルで温度を見える化し、「農水産物の輸出拡大に貢献する温度管理サービス『MiWAKERUⓇ』」が「第54回日本産業技術大賞 審査委員会特別賞」を受賞
https://rd.hitachi.co.jp/_ct/17762502
日立、イトーキ、トクヤマ、太陽光パネル板ガラスをそのままオフィス家具へ、アップサイクル実証
https://www.hitachi.co.jp/New/cnews/month/2025/09/0901.html
公開データのAI分析で強度と生分解性を両立させるバイオ由来樹脂用添加剤を探索し実証
https://main.spsj.or.jp/koho/koho_top.php
