Updated on 2024/09/21

写真a

 
LU,Renguo
 
Organization
Faculty of Engineering Science Professor
Title
Professor
Contact information
メールアドレス
External link

Degree

  • Doctor of Engineering ( 2009.3 )

Research Interests

  • synthetic lubricant oil

  • tribology

  • tribochemistry

  • tribotronics

  • surface analysis technology

  • surface and interface control

  • tribosensing

Research Areas

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

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Machine elements and tribology

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electron device and electronic equipment

Education

  • Iwate University   Graduate School, Division of Engineering   Material Engineering

    - 2009

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Research History

  • Kansai University   Faculty of Engineering Science Department of Mechanical Engineering   Professor

    2022.4

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  • Kansai University   Faculty of Engineering Science Department of Mechanical Engineering   Associate Professor

    2015.4 - 2022.3

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  • 国立大学法人岩手大学   学術研究員

    2014.5 - 2015.3

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  • 国立大学法人名古屋大学   研究員

    2011.6 - 2014.4

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  • 復旦大学   高分子材料学科   講師

    2003.7 - 2011.5

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    Country：China

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  • 復旦大学   高分子材料学科   助教

    2001.7 - 2003.6

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    Country：China

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Professional Memberships

Committee Memberships

  • 日本機械学会   IIP部門 部門幹事  

    2023.4 - Present   

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  •   第11回 日中トライボロジー先端フォーラム実行委員会, 実行委員  

    2023 - Present   

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  • International Tribology Conference (ITC Fukuoka 2023)実行委員会   実行委員  

    2023   

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  • MIPE2022（JSME-IIP/ASME-ISPS Joint Conference on Micromechatronics for Information and Precision Equipment）実行委員会   実行委員  

    2022   

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  • トライボロジー会議2021秋実行委員会   実行委員  

    2021   

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  • 日本学術振興会   特別研究員等審査会専門委員  

    2020.4 - 2022.3   

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  • International Conference on Mechanical Design and History of Technology 2019実行委員会   実行委員  

    2019   

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  • 日本機械学会   International Union委員  

    2018 - Present   

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  • 日本機械学会2018年度年次大会実行委員会   実行委員  

    2018   

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  • 日本機械学会   IIP部門委員  

    2016.4 - Present   

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  • 第7回 日中トライボロジー先端フォーラム実行委員会   実行委員  

    2016   

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Papers

  • Vibration-Based Scour-Detection for Bridge-Piers Using a Self-Powered Magnetostrictive Vibration Sensor

    Shinji Koganezawa, Shunya Terai, Hiroshi Tani, Renguo Lu, Shouhei Kawada

    IEEE Sensors Letters   8 ( 9 )   1 - 4   2024.9

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    Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

    DOI： 10.1109/lsens.2024.3432568

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  • Tribofilm Formation and Friction Reduction Performance on Laser-Textured Surface with Micro-Grooved Structures

    Qianru Li, Renguo Lu, Hiroshi Tani, Shohei Kawada, Shinji Koganezawa, Xujun Liu, Peihong Cong

    Lubricants   12 ( 3 )   91 - 91   2024.3

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    Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

    Tribofilms, resulting from tribochemical reactions involving lubricants, additives, and metal surfaces, are pivotal in reducing friction, preventing adhesion, and minimizing wear. This study investigates the tribological characteristics of textured surfaces in boundary lubrication, emphasizing the impact of surface texturing on tribofilm formation. Untextured surfaces manifest high friction coefficients and low wear owing to the development of thick tribofilms. However, debris accumulation impedes further tribochemical reactions, necessitating more energy for sliding and resulting in higher friction coefficients. Additionally, molybdenum dialkyl dithiocarbamate-derived MoS2 oxidation diminishes the expected lubrication effect. Textured surfaces exhibit lower friction coefficients and higher wear because the structure aids debris removal, promoting the formation of thinner tribofilms. Despite increased wear from solid-to-solid contact, textured surfaces facilitate an early fluid lubrication transition and enhance cavitation capacity, leading to reduced friction coefficients. We also consider the impact of sliding direction angles on friction coefficients, revealing that lower angles parallel to the grooves heighten friction, whereas higher angles enhance cavitation capacity. Unexpectedly, a 90° sliding direction angle increases the friction coefficients, attributed to MoS2 distribution in the tribofilms. These results provide crucial insights for optimizing lubrication strategies and enhancing wear resistance in boundary lubrication scenarios.

    DOI： 10.3390/lubricants12030091

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  • Ionic Liquid and PVDF Composite Films for Triboelectric Nanogenerator

    Hiroshi Tani, Yangwei Zhu, Shouhei Kawada, Renguo Lu, Shinji Koganezawa

    2023 IEEE 22nd International Conference on Micro and Nanotechnology for Power Generation and Energy Conversion Applications (PowerMEMS)   2023.12

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    Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

    DOI： 10.1109/powermems59329.2023.10417445

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  • The Influence of Electric Current on the Friction Behavior of Lubricant Molecules Reviewed

    Renguo Lu, Shouhei Kawada, Hiroshi Tani, Shinji Koganezawa

    Tribology Online   18 ( 3 )   83 - 90   2023.7

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  • Feasibility study of reduction in sound-pressure induced vibration in hard disk drives using an adaptive feed-forward control Reviewed

    Shinji Koganezawa, Kensei Funai, Hiroshi Tani, Renguo Lu, Shohei Kawada

    IEEE Transactions on Magnetics   59   8600905   2023.6

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  • Effect of Humidity on Head Smear Generation in Head-Assisted Magnetic Recording Reviewed

    Hiroshi Tani, Hiroshi Kurafuji, Norio Tagawa, Shohei Kawada, Renguo Lu, Shinji Koganezawa

    IEEE Transactions on Magnetics   59   3200905   2023.6

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  • Control of head smear generation by diamond-like carbon films using an external electric field Reviewed

    Tani, H, Lu, R, Koganezawa, S. Tagawa

    Microsyst Technol   29   295 - 300   2023.1

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  • Effects of Oxygen on Smear Formation in Heat Assisted Magnetic Recording System Reviewed

    K Yakata, H Kurafuji, H Tani, R Lu, S Koganezawa, S Kawada, N Tagawa

    Tribology Online   17 ( 4 )   348 - 355   2022.12

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  • Alkylated Polyphenyl Ethers as High-Performance Synthetic Lubricants Reviewed

    Renguo Lu, Hiroshi Tani, Shinji Koganezawa, Mayayuki Hata

    Lubricants   10   275   2022.10

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  • Young’s Modulus of Fatty Acid Adsorption Films on Si Surface Measured Using Ar Gas Cluster Ion Beams Reviewed

    Hiroshi Tani, Norio Tagawa, Shouhei Kawada, Renguo Lu, Shinji Koganezawa

    Tribology Online   17, 2, 110-117 ( 2 )   110 - 117   2022.6

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    Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

    DOI： 10.2474/trol.17.110

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  • Effective Elastic Moduli of Magnetic Disks with Molecularly Thin Liquid Lubricant Films Determined Using Ar-Gas Cluster Ion Beam Reviewed

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Tribology Online   vol17, No.1, 32-43 ( 1 )   32 - 43   2022.2

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    Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

    DOI： 10.2474/trol.17.32

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  • Magnetostrictive vibration sensor for a self- powered structural health monitoring system Reviewed

    Shinji Koganezawa, Tomotake Ishii, Hiroshi Tani, Renguo Lu, Norio Tagawa

    JSME Journal of Advanced Mechanical Design, Systems, and Manufacturing   Vol. 16, No. 1, JAMDSM0010   2021.12

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  • Evaluating the Elastic Moduli of Ultra-Thin Liquid Perfluoropolyether Lubricant Films on Diamond-Like Carbon Films Using Ar-Gas Cluster Ion Beams Reviewed

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Tribology Online   16, 4: 309-316 ( 4 )   309 - 316   2021.12

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    Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

    DOI： 10.2474/trol.16.309

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  • Electric Field Effect on Friction Coefficient of Diamond-Like Carbon Film Heated by Laser Irradiation Reviewed

    Hiroshi Tani, Yuki Izutani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Tribology Letters   69: 103 ( 3 )   2021.9

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

    DOI： 10.1007/s11249-021-01482-2

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    Other Link： https://link.springer.com/article/10.1007/s11249-021-01482-2/fulltext.html

  • Investigation of mechanism of smear formation from diamond-like carbon films on heating Reviewed

    Hiroshi Tani, Renguo Lu, Shinji Konagezawa, Norio Tagawa

    Microsystem Technologies   27: 2243-2255   2021.6

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  • Experimental Study on Smear Characteristics Upon Laser Heating in Air and Helium in Heat-Assisted Magnetic Recording Reviewed

    Norio Tagawa, Hiroshi Tani, Shinji Koganezawa, Renguo Lu

    IEEE Transactions on Magnetics   57: 3200405 ( 2 )   1 - 5   2021.2

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    Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

    DOI： 10.1109/tmag.2020.3012979

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  • Effect of Diamond-Like Carbon Coating on Preventing the Ingress of Hydrogen into Bearing Steel Reviewed

    Renguo Lu, Sora Shiode, Takayuki Hamada, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    Tribology Transactions   64: 157-166 ( 1 )   157 - 166   2021.1

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    Publishing type：Research paper (scientific journal)   Publisher：Informa UK Limited  

    DOI： 10.1080/10402004.2020.1815919

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  • ELECTROMAGNETIC ENERGY HARVESTER for TRANSPORTATION INFRASTRUCTURE USING VEHICLE-TREAD FORCE

    Shinji Koganezawa, Kota Morii, Hiroshi Tani, Renguo Lu, Norio Tagawa

    Proceedings of the ASME 2021 30th Conference on Information Storage and Processing Systems, ISPS 2021   2021

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Mechanical Engineers (ASME)  

    We propose a novel electromagnetic energy-harvesting device (EHD) for structural health monitoring systems of transportation infrastructures. The EHD is embedded in the road surface and uses the tread force of cars as the input force when tires of cars pass over it. Because the input force is very fast, the proposed EHD can generate a large amount of energy. The footprint of the device is 20× 20 mm, its height is 7.5 mm, and its volume is 2.4 cm3. We measured the energy generated when a bicycle passed over the EHD 34 times at various speeds between 5 and 15 km/h. Subsequently, we obtained the regression curve from the results, which showed the relationship between the bicycle speed and generated energy, and estimated the electric energy generated by car at higher speeds. The results showed that, even though the size of the EHD was small, electric energies of 100 ?J, and 1.0 mJ could be generated at car speeds of 17 km/h, and 52 km/h, respectively.

    DOI： 10.1115/ISPS2021-63672

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  • CONTROL of HEAD SMEAR GENERATED from DLC FILMS USING AN EXTERNAL ELECTRIC FIELD

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Proceedings of the ASME 2021 30th Conference on Information Storage and Processing Systems, ISPS 2021   2021

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Mechanical Engineers (ASME)  

    In this study, the dependence of the electric field between the magnetic disk and Si wafer, used as the counter surface, on the hydrocarbon smear generated from the diamond-like carbon (DLC) overcoat was investigated. As a result, the positive electric field from the disk to the Si wafer increased the amount of smear, and the negative field reduced it. The positive electric field was estimated to extract hydrocarbon ions from the thermal plasma toward the Si wafer, and the opposite field attracts the hydrocarbon ions to the DLC surface. Therefore, the electric field between the slider and disk possibly controls the smear generation from the DLC overcoat, which is heated by laser irradiation in the heat-assisted magnetic recording).

    DOI： 10.1115/ISPS2021-63202

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  • Hybrid lubricant film with high bonding ratio and high coverage Reviewed

    Hiroshi Tani, Yuki Uesaraie, Reguo Lu, Shinji Koganezawa, Norio Tagawa

    Microsystem Technologies   26: 3331-3337 ( 11 )   3331 - 3337   2020.11

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

    DOI： 10.1007/s00542-020-04806-9

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    Other Link： http://link.springer.com/article/10.1007/s00542-020-04806-9/fulltext.html

  • Development of Vibration Sensor Using Giant Magnetostrictive Material for Self-Powered Structural Health Monitoring System

    Shinji Koganezawa, Tomotake Ishii, Hiroshi Tani, Renguo Lu, Norio Tagawa

    Proceedings of IEEE Sensors   2020-   2020.10

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

    A novel vibration-sensing device based on the giant magnetostrictive effect for a self-powered structural health monitoring system was developed. This device can produce a large voltage because the magnetostrictive rod, in principle, can generate a large variation in magnetic flux density, even when it is subjected to small and low-frequency vibrations of the bridge girder. Therefore, the device could function as a power generator to supply power to a storage battery, when it is not being used as a vibration sensor, to drive the electric circuit. A field test for the developed device was conducted. The experimental results confirmed that the device worked as a vibration sensor with considerable accuracy in detecting the natural frequency of the bridge, even when subjected to the intermittent load of passing cars.

    DOI： 10.1109/SENSORS47125.2020.9278840

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  • Low Friction of Diamond-Like Carbon Film Due to Liquid Hydrocarbon Generated by Laser Heating in a Nitrogen Gas Environment Reviewed

    H. Tani, R. Naito, R. Lu, S. Koganezawa, N. Tagawa

    Tribology Letters   68: 88 ( 3 )   2020.9

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

    DOI： 10.1007/s11249-020-01333-6

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    Other Link： https://link.springer.com/article/10.1007/s11249-020-01333-6/fulltext.html

  • Harvesting Energy Using Triboelectric Nanogenerator Mounted inside Rolling Tire Reviewed

    Hiroshi Tani, Mutsuki Sugimoto, Kazuhisa Fushihara, Yukio Nakano, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Sensors and Materials   32: 2539–2549 ( 7 )   2539 - 2539   2020.7

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    Publishing type：Research paper (scientific journal)   Publisher：MYU K.K.  

    DOI： 10.18494/sam.2020.2827

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  • Smear and Decomposition Mechanism of Magnetic Disk PFPE Lubricant Film by Laser Heating in Air and Helium Conditions Reviewed

    Kenji Yakata, Satoki Ichikawa, Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Tribology Online   15:186-193 ( 3 )   186 - 193   2020.6

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    Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

    DOI： 10.2474/trol.15.186

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  • TOF-SIMS analysis of perfluoropolyether lubricant smear transferred from disk surface following laser heating Reviewed

    Hiroshi Tani, Yuta Shibahara, Reguo Lu, Shinji Koganezawa, Norio Tagawa

    Microsystem Technologies   26: 79-88 ( 1 )   79 - 88   2020.1

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

    DOI： 10.1007/s00542-019-04447-7

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    Other Link： http://link.springer.com/article/10.1007/s00542-019-04447-7/fulltext.html

  • Experimental study of lubricant depletion induced by pulsed laser irradiation heating in heat-assisted magnetic recording Reviewed

    Norio Tagawa, Hiroshi Tani, Yuki Uesaraie, Shinji Koganezawa, Renguo Lu

    Microsystem Technologies   26: 5-10 ( 1 )   5 - 10   2020.1

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

    DOI： 10.1007/s00542-018-4259-6

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    Other Link： http://link.springer.com/article/10.1007/s00542-018-4259-6/fulltext.html

  • Numerical study on the effects of linear protrusion on flow-induced carriage excitation force in hard disk drives Reviewed

    Shinji Koganezawa, Shotaro Tsuda, Hiroshi Tani, Renguo Lu, Norio Tagawa

    Microsystem Technologies   26: 33-47 ( 1 )   33 - 47   2020.1

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

    DOI： 10.1007/s00542-019-04398-z

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    Other Link： http://link.springer.com/article/10.1007/s00542-019-04398-z/fulltext.html

  • Investigation of smear formation mechanism from DLC film by heating

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    ASME 2020 29th Conference on Information Storage and Processing Systems, ISPS 2020   2020

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Mechanical Engineers (ASME)  

    The formation of head smear from DLC films on magnetic disks was confirmed by a simulated heating experiment. DLC films of 100-nm thickness were prepared and heated on a hot plate in an environmental gas chamber. Smear on a silicon wafer placed 3 mm above the DLC surface was observed after heating of the DLC film. The smear amount was quantified using the carbon intensity of the smear measured by XPS. In air, the carbon concentration decreased with the heating temperature
    however, the carbon concentration increased with temperature in nitrogen. The carbon concentration of the smear in the air environment was smaller than that of nitrogen. As the result of comparison of smears on DLCs with various hydrogen concentrations, more decomposed gas is generated from the DLC film as the amount of hydrogen contained in the DLC increases, and this value increases at lower temperatures. This result suggests that DLC films with low hydrogen concentrations generate a smaller amount of decomposition gas than those with high hydrogen concentrations during heating. In addition, Raman spectra suggest that the DLC degraded by heating and the hydrocarbon gas-like materials were generated from the DLC film because the DLC films include carbon and hydrogen. Because fragments of 250–500 atomic mass units were observed in the TOF-SIMS spectra of smears, the smear is estimated to consist of a hydrocarbon of relatively high molecular weight.

    DOI： 10.1115/ISPS2020-1902

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  • Tribological properties of alkyldiphenylethers in boundary lubrication Reviewed

    Renguo Lu、Masaya Morimoto,Hiroshi Tani,Norio Tagawa, Shinji Koganezawa

    Lubricants   7: 112   2019.12

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  • Nanoscale wear of carbon overcoat subjected to laser heating in an inert gas environment

    Norio Tagawa, Hiroshi Tani, Shinji Koganezawa, Renguo Lu

    Lecture Notes in Mechanical Engineering   691 - 704   2019

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Pleiades Publishing  

    Because the diamond-like carbon (DLC) thin film overcoat on either a hard disk surface or an air bearing surface plays an important role in maintaining the reliability and durability of the head-disk interface, nanoscale DLC wear and degradation is a critical issue in heat-assisted magnetic recording (HAMR). The use of helium in hard disk drives (HDDs) has been developed and put into practical use to decrease air-induced structural vibrations, and temperature rise. In this study, fundamental experiments were conducted to understand the wear and related degradation characteristics of an ultra-thin DLC overcoat subjected to laser heating in both air and inert gas environments, using a pin-on-disk tester. An inert gas environment was simulated using helium gas. The experiments were conducted using DLC-coated glass pins and actual magnetic disks without a lubricant film. The differences in the wear and degradation characteristics of a DLC overcoat on the pin and disk surfaces between inert gas and air environments were investigated after wear tests were performed, primarily through Raman spectroscopy. We found that wear and graphitization of DLC films became greater with laser heating, while the friction coefficients between the pin and magnetic disk became markedly smaller. However, our tests also revealed that wear and graphitization of the DLC film were significantly less in an inert gas environment than in an air environment. This is because the wear observed in this experiment was predominantly due to a wear mechanism that is based on tribo-chemical oxidation.

    DOI： 10.1007/978-981-13-0411-8_62

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  • Effect of laser heating on the smear behavior of pfpe lubricant films on magnetic disks in air and helium

    N. Tagawa, K. Yakata, H. Tani, S. Koganezawa, R. Lu

    Proceedings of 10th International Scientific Conference BALTTRIB 2019   280 - 284   2019

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Vytautas Magnus University  

    We investigated the smear characteristics upon laser heating in air and helium. We used magnetic disks coated with the perfluoropolyether (PFPE) lubricant D-4OH. The surface of the rotating disk was heated by laser irradiation using a pin-on-disk tester setup in a sealed chamber. The temperature was varied from 258°C to 540°C. When the lubricant film was heated by the laser, the lubricant evaporated from the surface of the disk by desorption or decomposition and adhered onto a hemispherical glass pin placed 5 μm above the disk surface as smears. The smears on the pin were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). It was found that the amount of smear under exposure to helium gas is greater than that to air at high temperatures. In addition, this interesting result may be attributed not only to the different lubricant depletion mechanisms due to laser heating under the two environmental conditions, but also to the diamond-like carbon (DLC) thin film at a relatively low temperature of approximately 260°C.

    DOI： 10.15544/balttrib.2019.44

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  • Effect of laser heating on nanoscale wear of DLC thin films in an air environment Reviewed

    Norio Tagawa, Hiroshi Tani, Shinji Koganezawa, Renguo Lu

    Microsystem Technologies   24: 4605-4611 ( 11 )   4605 - 4611   2018.11

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

    DOI： 10.1007/s00542-018-3875-5

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    Other Link： http://link.springer.com/content/pdf/10.1007/s00542-018-3875-5.pdf

  • Structural changes of perfluoropolyether lubricant accumulated on the pin surface during laser heating Reviewed

    Hiroshi Tani, Yuta Shibahara, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    IEEE Transactions on Magnetics   54: 3300505   2018.11

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  • Smear growth on head slider surface from siloxane outgas on heat assisted magnetic recording Reviewed

    Hiroshi Tani, Yuki Uesaraie, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Microsystem Technologies   24: 4641–4648   2018.11

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  • Frequency analysis of disturbance torque exerted on a carriage arm in hard disk drives using Hilbert–Huang transform Reviewed

    Shinji Koganezawa, Shotaro Tsuda, Hiroshi Tani, Renguo Lu, Norio Tagawa

    IEEE Transactions on Magnetics   54: 3100906   2018.11

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  • A Study on the tribofilm growth and tribological properties of tribofilms formed from zinc dialkyl dithiophosphate (ZDDP) and molybdenum dialkyl dithiocarbamate (MoDTC) Reviewed

    Renguo Lu, Sora Shiode, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    Tribology Online   13: 157-165   2018.7

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  • 摩擦帯電センサによる転がり軸受の回転速度と温度のモニタ Reviewed

    谷 弘詞, 沖塩 大樹, 呂 仁国, 小金沢 新治, 多川 則男

    トライボロジスト   Vol.63,No.6, 426-433   2018.6

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  • Smear growth on head slider surface from siloxane outgas on heat assisted magnetic recording

    Hiroshi Tani, Yuki Uesaraie, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Microsystem Technologies   Vol.24, No.11, 2018, pp.4641–4   1 - 8   2018.3

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Verlag  

    In this study, the smear by the lubricant and siloxane pickup at the laser heating in the heat assisted magnetic recording (HAMR) was evaluated using our developed noncontact pin-on-disk test. The smear area on the glass pin surface was measured on the disks with three types of different lubricant films prepared by changing the ultraviolet exposure condition, rinse condition, and lubrication process. The amount of siloxane adsorbed on disk surface relates with the siloxane wettability obtained from the contact angle of siloxane for disk surface and that increased as the siloxane wettability increases. On the other hand, the lubricant pickup increases as the physical and hydrogen bonding fractions increase. Overall, these data suggest that the sufficiently low surface free energy is needed by the lubricant film with only the chemical bonding fraction to reduce the lubricant and siloxane smear at the laser heating of HAMR, because the lubricant fractions of physical and hydrogen bonding increase the lubricant pickup and the much amount of siloxane adsorbs on disks with the large surface free energy.

    DOI： 10.1007/s00542-018-3839-9

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  • Adsorption Properties of an Ultrathin PFPE Lubricant with Ionic End-Groups for DLC Surfaces

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    IEEE Transactions on Magnetics   54 ( 2 )   2018.2

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

    This paper examines the adsorption properties of the perfluoropolyether (PFPE) lubricant SNH2 with an ionic end-group (i.e., amine salt with a diphenylether moiety) for magnetic disk surfaces in heat-assisted magnetic recording (HAMR) drives. For comparison, the well-known lubricant Z-tetraol was used as a reference material. Initially, strong interactions between the ionic end-groups of SNH2 and an applied electric field in the lubricant solution were established. The surface free energy and bonding ratio were also compared before and after ultraviolet (UV) light exposure to diamond-like carbon (DLC) disk surfaces onto, which the lubricants were coated, with their photoelectron currents measured during UV exposure. In addition, the structural characteristics of the SNH2 lubricant on the DLC surface were analyzed using a time-of-flight secondary mass spectroscopy. Furthermore, the thermal stabilities of the lubricant films were compared following laser heating. Overall, SNH2 showed higher adsorption to the DLC surface than Z-tetraol and interacted more strongly with the electric field in the lubricant solution. Furthermore, although SNH2 without UV exposure showed a large polar surface energy, this energy decreased considerably after UV exposure. This decrease is attributed to interactions between photoelectrons emitted from the DLC surface and the ionic bonds of the SNH2 molecules
    the cationic segments of the SNH2 ionic bonds dissociate, whereas the anionic main-chains chemisorb on the DLC surface at the electron holes generated from the ejected photoelectrons. SNH2 after the UV exposure showed high thermal stability because of its strong bonding to the DLC surface. Overall, these results demonstrate that a PFPE lubricant with ionic end-groups may be an effective lubricant for HAMR applications.

    DOI： 10.1109/TMAG.2017.2724038

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  • Adsorption properties of an ultrathin PFPE lubricant with ionic end-groups for DLC surfaces Reviewed

    Hiroshi Tani,Renguo Lu,Shinji Koganezawa,Norio Tagawa

    IEEE Transactions on Magnetics   54: 3300106   2018.2

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  • 接触型トライボチャージ発電機の開発 Reviewed

    谷弘詞,呂仁国,小金沢新治,多川則男

    トライボロジスト   Vol.63, No.1, 52-59   2018.1

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  • TOF-SIMS analysis of accumulated PFPE lubricant smear following laser heating

    Hiroshi Tani, Renguo Lu, Norio Tagawa, Yuta Shibahara, Shinji Koganezawa

    ASME-JSME 2018 Joint International Conference on Information Storage and Processing Systems and Micromechatronics for Information and Precision Equipment, ISPS-MIPE 2018   2018

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：American Society of Mechanical Engineers (ASME)  

    The structural and molecular weight changes to lubricant picked up following laser heating in heat-assisted magnetic recording (HAMR) were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The intensity of the ion mass fragments depended on the decomposition pathways and changed drastically, as did the average molecular weight of the picked-up lubricant as heating temperature increased. The fragment series formed by the dissociation of end groups with low molecular weights (CH3O+) showed a high intensity at temperatures under 300 °C, whereas at temperatures over 400 °C, the fragments series formed by the dissociation of the end-group component (C5H9O4F2+) increased. Overall, the results presented herein suggest that the chemical and thermal stability of the hydrocarbon terminal ends of lubricants should be improved in order to decrease depletion of the lubricant film and lubricant pickup by laser heating in HAMR.

    DOI： 10.1115/ISPS-MIPE2018-8515

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  • Insect-sized flapping-flight robot using dry friction-based self-excited vibration

    Shinji Koganezawa, Takahiro Fujiwara, Taiki Usami, Ryo Kawasaka, Lu Renguo, Hiroshi Tani, Norio Tagawa

    European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 18th International Conference and Exhibition, EUSPEN 2018   195 - 196   2018

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：euspen  

    It is expected that, in the future, quadrotor helicopters (quadcopters) will be employed in many applications, several of which require the quadcopters to be extremely small. However, it is difficult for smaller quadcopters to achieve a sufficient lift force for flight because, with reduction in the propeller diameter, the lift force decreases more sharply than the mass does. To miniaturize flying robots, we developed a flapping-flight robot employing self-excited vibration based on dry friction, inspired by the flight mechanism of bees. The proposed structure uses a simple DC motor and is easy to control
    a large flapping angle can be obtained by operating at the resonant frequency using dry friction-based self-excited vibration with robustness. The designed flapping-flight robot is similar to a hornet in size with a body length of 5.4 mm and wingspan of 57.2 mm
    it weighs 970 mg, including the weight of a motor and battery.

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  • Rotational speed and temperature monitoring of ball bearing using tribocharge sensor

    Hiroshi Tani, Daiki Okishio, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Toraibarojisuto/Journal of Japanese Society of Tribologists   63 ( 6 )   426 - 433   2018

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

    The tribocharge sensor to monitor the rotational speed and the temperature of ball bearing was fabricated and we studied the basic feasibility this tribocharge sensor. The tribocharge sensor was built up by the segmented electrode on rotor, the segmented electrode on stator. Electrode material is Cu of 35 μm thick and the material of base film is polyirude of 25 μm thick, This sensor was attached on the side on the ball bearing. This tribocharge sensor outputted the pulse voltage from the stator electrode. The output voltage was proportional to the rotational speed of ball bearing. The generated electric power was 0.2 μW at 2000 rpm, however, the electric power of 20 μW was expected by the reduction of PFTE film thic mess. On the other hand, the temperature of ball bearing was estimated by the envelope of negative voltage from the tribocharge sensor, and the estimated temperature approximately agreed with the temperature estimated by the friction force.

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  • Development of contact type tribocharge power generator

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Toraibarojisuto/Journal of Japanese Society of Tribologists   63 ( 1 )   52 - 59   2018

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

    The contact type of tribocharge power generator was developed. This tribocharge power generator has a simple structure which two types of tribocharging films on electrode are laminated by silicon rubbers. That generated the volume density of electric power of 94μW/cm3 under the condition of 40 Hz, 2G, and 55kPa. As the results, we confirmed that the tribocharge power generator was useful for the energy harvesting and sensing the acceleration.

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  • Friction Characteristics of Ultrathin Perfluoropolyether Boundary Lubricant Films Subjected to Laser Irradiation Heating in Heat-Assisted Magnetic Recording

    Norio Tagawa, Hiroshi Tani, Shinji Koganezawa, Renguo Lu

    IEEE TRANSACTIONS ON MAGNETICS   53 ( 11 )   2017.11

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    We investigated the laser-heating-temperature dependence of the friction characteristics of magnetic disks coated with boundary lubricant films by using a pin-on-disk tester and discussed the fundamental characteristics observed. In the contact area of the glass pin and disk, we observed the area that showed a buildup and depletion of the lubricant film thickness. The amount of buildup and depletion increased with increasing heating temperature. It was found that the friction coefficient of each lubricant film initially decreased as the temperature increased. Thereafter, the minimum value of the friction coefficient of each test lubricant occurred at a specific temperature, resulting in an increase in the friction coefficient inversely as the temperature further increased. It was suggested that the specific temperature corresponds to the transition temperature at which the test lubricant film evaporates. In addition, it was also suggested that the thermal durability of the lubricant film improved because of ultraviolet treatment.

    DOI： 10.1109/TMAG.2017.2697478

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  • Friction characteristics of ultrathin perfluoropolyether boundary lubricant films subjected to laser irradiation heating in heat-assisted magnetic recording Reviewed

    Norio Tagawa,Hiroshi Tani,Shinji Koganezawa,Renguo Lu

    IEEE Transactions on Magnetics   53: 2501204   2017.11

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  • Low friction properties of associated carboxylic acids induced by molecular orientation Reviewed

    Renguo Lu, Shigeyuki Mori, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    Tribology International   113: 36-42   2017.9

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  • Low friction properties of associated carboxylic acids induced by molecular orientation Reviewed

    Renguo Lu, Shigeyuki Mori, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    TRIBOLOGY INTERNATIONAL   113   36 - 42   2017.9

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

    Molecular alignment is key to achieving an ultra-low friction coefficient. We prepared associated carboxylic acids using oleic acid and p-pentylbenzoic acid via hydrogen bonding, involving a benzene ring and an eight-membered cyclic carboxylic acid in the molecules. We investigated frictional properties when these were added into a base oil and found that the associated carboxylic acids decreased the traction coefficient in EHL and boundary lubrication, although the viscosity increased. An in situ micro Fourier transform infrared spectroscope showed that both the eight-membered cyclic carboxylic acid and the benzene ring were oriented parallel to the shearing force, leading to the low friction coefficient.

    DOI： 10.1016/j.triboint.2016.10.042

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  • Device for direct measurement of dynamic viscoelastic properties of solid-state materials at frequencies higher than 1 kHz Reviewed

    Shinji Koganezawa, Yuta Katsuta, Renguo Lu, Hiroshi Tani, Norio Tagawa

    RHEOLOGICA ACTA   56 ( 5 )   477 - 486   2017.5

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

    Viscoelastic (VE) materials are widely used in daily life. For the effective utilization of VE materials, it is necessary to know their viscoelasticity with accuracy over a wide range of frequencies, especially for high frequencies. Currently, the viscoelasticity of solid-state materials is directly measured only in the low-frequency range; for high frequencies, it is estimated based on the time-temperature superposition (TTS) principle. However, it is generally recognized that the TTS principle is suitable only for estimating the viscoelasticity of rheologically simple materials for temperatures within a limited range that is higher than the glass-transition temperature. In this paper, we propose a device that can directly measure the shear modulus and tan delta values of solid-state VE materials at high frequencies. We also propose a method for compensating for the shear deformation mode resonance of VE materials based on the mass of the moving part, to gain a more accurate understanding of viscoelasticity in the high-frequency range, and discuss the causes of errors in the compensation method. Finally, we report the VE properties of natural rubber (NR 65 IRHD) measured using the developed device and compensation method, and compare the measured results with those obtained using commercial VE measurement equipment.

    DOI： 10.1007/s00397-017-1010-7

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  • Device for direct measurement of dynamic viscoelastic properties of solid-state materials at frequencies higher than 1 kHz Reviewed

    Shinji Koganezawa, Yuta Katsuta, Renguo Lu, Hiroshi Tani, Norio Tagawa

    Rheologica Acta   56: 477-486   2017.5

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  • Decomposition of perfluoropolyether lubricant on air-bearing surfaces during heat-assisted magnetic recording Reviewed

    Norio Tagawa, Hiroshi Tani, Hiroaki Asada, Renguo Lu, Shinji Koganezawa

    IEEE Transactions on Magnetics   53: 3301505   2017.3

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  • Decomposition of Perfluoropolyether Lubricant on Air-Bearing Surfaces During Heat-Assisted Magnetic Recording Reviewed

    Norio Tagawa, Hiroshi Tani, Hiroaki Asada, Renguo Lu, Shingi Koganezawa

    IEEE TRANSACTIONS ON MAGNETICS   53 ( 3 )   2017.3

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    Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    The thermal decomposition of a thin film of D-4OH lubricant under heating conditions on air-bearing surfaces, such as those found in magnetic recording devices, was investigated using time-of-flight secondary ion mass spectroscopy. The substrates used in this experiment were those of actual magnetic head sliders with diamond-like carbon (DLC) thin-film coatings. Two kinds of surfaces were prepared: an undisturbed DLC thin-film surface and an Al2O3 surface exposed by sputtering of the DLC thin film. Changes in the positive mass spectra as a result of heating confirmed that thermal decomposition of the D-4OH lubricant thin-film occurred, and that it was catalytically accelerated by Al2O3 at heating temperatures below 150 degrees C. This observation contrasts with the fact that the D-4OH lubricant thin film on the undisturbed DLC thin-film surface did not decompose.

    DOI： 10.1109/TMAG.2016.2627532

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  • Ultrathin PFPE/DLC hybrid overcoat for magnetic disks by photoelectron-assisted chemical vapor deposition Reviewed

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    IEEE Transactions on Magnetics   53: 3300906   2017.3

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  • Engineering experiment of tribology: Friction and wear of rolling bearings

    Renguo Lu, Hiroshi Tani

    Toraibarojisuto/Journal of Japanese Society of Tribologists   62 ( 5 )   346 - 349   2017

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    Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japanese Society of Tribologists  

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  • Decomposition of perfluoropolyether lubricant picked up on actual air bearing surface in heat-assisted magnetic recording Reviewed

    Norio Tagawa, Hiroshi Tani, Hiroaki Asada, Renguo Lu, Shinji Koganezawa

    2016 Asia-Pacific Magnetic Recording Conference, APMRC 2016   2016.7

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    Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Institute of Electrical and Electronics Engineers Inc.  

    The thermal decomposition of D-4OH lubricant thin film on an actual air-bearing surface under heating conditions was investigated using time-of-flight secondary ion mass spectroscopy (TOF-SIMS). The substrates used in this experiment are those of actual magnetic head sliders with diamond-like carbon (DLC) thin-film coatings. Two kinds of surfaces were prepared
    an undisturbed DLC thin-film surface and an AhO3 surface exposed by sputtering of the DLC thin film. Comparison of the changes in the positive mass spectra due to heating confirmed that thermal decomposition of the D-4OH lubricant thin-film occurred and that it could be accelerated by the catalysis of Al2O3 at heating temperatures below 150°C. This is despite the fact that the D-4OH lubricant thin-film on the undisturbed DLC thin-film surface did not decompose.

    DOI： 10.1109/APMRC.2016.7524262

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  • The effect of the chemical structures of synthetic hydrocarbon oils on their tribochemical decomposition Reviewed

    Renguo Lu, Hidetaka Nanao, Koji Takiwatari, Shigeyuki Mori, Yoshinori Fukushima, Youichi Murakami, Shozo Ikejima, Tadaaki Konno

    Tribology Letters   60:27   2015.11

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  • Effect of heat treatment on the mechanical and tribological properties of polyphenylene sulfide fiber materials Reviewed

    Yuning Ma, Peihong Cong, Xujun Liu, Renguo Lu

    Journal of Macromolecular Science, Part B: Physics   53: 1786-1799   2014.12

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  • Influence of surface roughness and coating on the friction properties of nanometer-thick liquid lubricant films Reviewed

    Renguo Lu, Hedong Zhang, Yasunaga Mitsuya, Kenji Fukuzawa, Shintaro Itoh

    Wear   319: 56-61   2014.11

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  • Contributions of mobile and bonded molecules to dynamic friction of nanometer-thick perfluoropolyether films coated on magnetic disk surfaces Reviewed

    Renguo Lu, Hedong Zhang, Yasunaga Mitsuya, Kenji Fukuzawa, Shintaro Itoh,

    Tribology Letters   54: 237-247   2014.6

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  • Surface functionalization by fine ultraviolet-patterning of nanometer-thick liquid lubricant films Reviewed

    Renguo Lu, Hedong Zhang, Suguru Komada, Yasunaga Mitsuya, Kenji Fukuzawa, Shintaro Itoh

    Applied Surface Science   vol. 320, PP.102-111   2014

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  • Friction measurements of nanometer-thick lubricant films using ultra-smooth sliding pins treated with gas cluster ion beam Reviewed

    Renguo Lu, Hedong Zhang, Yasunaga Mitsuya, Kenji Fukuzawa, Shintaro Itoh

    Applied Surface Science   280: 619-625   2013.9

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  • An investigation into the migration of segments in crosslinked fluorinated polyimide adhesive Reviewed

    Zhongyuan Huang, Renguo Lu, Ting Huang, Hongyan Wang, Tongsheng Li,

    Journal of Macromolecular Science, Part B: Physics   52: 937-949   2013.7

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  • Adhesion properties of monolayer lubricant films coated on magnetic disk surfaces: contributions of mobile and bonded molecules Reviewed

    Renguo Lu, Hedong Zhang, Masashi Itakura, Kenji Fukuzawa, Shintaro Itoh,

    IEEE Transactions on Magnetics   48: 4269-4272   2012.11

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  • The mechanical and tribological properties of aramid (Twaron) fabric/polytetrafluoroethylene composites Reviewed

    Pei Liu, Renguo Lu, Hongyan Wang, Ting Huang, Tongsheng Li

    Journal of Macromolecular Science, Part B: Physics   51:1693-1704   2012.9

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  • Cure and thermal stability of poly(amide-amidic acid)-cured tetraglycidyl 4,4’-diaminodiphenylmethane Reviewed

    Haiming Chen, Renguo Lu, Pei Li, Hongyan Wang, Ting Huang, Zhongyuan Huang, Tongsheng Li

    Journal of Applied Polymer Science   125, 2854-2860   2012.8

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  • Modification of polyetherimide by phenylethynyl terminated agent for improved tribological, macro- and micro-mechanical properties Reviewed

    Ting Huang, Pei Liu, Renguo Lu, Zhongyuan Huang, Haiming Chen, Tongsheng Li

    Wear   292: 25-32   2012.7

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  • Effect of surface treated carbon nanotubes on the mechanical and tribological performances of phenolic resin Reviewed

    Hongyan Wang, Renguo Lu, Zhongyuan Huang, Ting Huang, Peihong Cong, Tongsheng Li

    Journal of Macromolecular Science, Part B: Physics   51: 1148-1158   2012.6

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  • Tribological properties of modified carbon fabric/polytetrafluoroethylene composites Reviewed

    Pei Liu, Ting Huang, Renguo Lu, Tongsheng Li

    Wear   289, 17-25   2012.6

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  • Tensile and tribological properties of polytetrafluroethylene homocomposites Reviewed

    Pei Liu, Renguo Lu, Ting Huang, Peihong Cong, Sisi Jiang

    Wear   289: 65-72   2012.6

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  • Surface modification by air-plasma treatment and its effect on the tribological behavior of hybrid fabric–polyphenylene sulfide composites Reviewed

    Ting Huang, Renguo Lu, Yuning Ma, Pei Liu, Haiming Chen, Zhongyuan Huang, Tongsheng Li

    Journal of Macromolecular Science, Part B: Physics   51, 1011-1026   2012.5

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  • Chemically modified graphene/polyimide composite films based on utilization of covalent bonding and oriented distribution Reviewed

    Ting Huang, Renguo Lu, Chao Su, Hongna Wang, Zheng Guo, Pei Liu, Zhongyuan Huang, Haiming Chen, Tongsheng Li

    ACS Applied Materials & Interfaces   4: 2699-2708   2012.4

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  • A study on the mechanical and tribological properties of carbon fabric/PTFE composites Reviewed

    Pei Liu, Renguo Lu, Ting Huang, Hongyan Wang, Tongsheng Li

    Journal of Macromolecular Science, Part B: Physics   51: 786-797   2012.4

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  • Study on the friction and sliding wear behavior of hybrid polytetrafluoroethylene/Kevlar fabric composites filled with polyphenylene sulfide Reviewed

    Ting Huang, Renguo Lu, Yuning Ma, Pei Liu, Tongsheng Li

    Journal of Macromolecular Science, Part B: Physics   51, 109-124   2012.1

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  • Effect of grafted polytetrafluoroethylene nanoparticles on the mechanical and tribological performances of phenol resin Reviewed

    Hongyan Wang, Renguo Lu, Ting Huang, Yuning Ma, Peihong Cong, Tongsheng Li

    Materials Science and Engineering A   528: 6878-6886   2011.8

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  • Investigation on the tribological properties of POM modified by Nano-PTFE Reviewed

    Ting Huang, Renguo Lu, Hongyan Wang, Yuning Ma, Jianshu Tian, Tongsheng Li

    Journal of Macromolecular Science, Part B: Physics   50: 1235-1248   2011.7

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  • Tribological behaviors of fluorinated polyimides at different temperatures Reviewed

    Tongsheng Li, Jianshu Tian, Ting Huang, Zhongyuan Huang, Hongyan Wang, Renguo Lu

    Journal of Macromolecular Science, Part B: Physics   50: 860-870   2011.5

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  • Investigation on tribological properties of fluorinated polyimide Reviewed

    Jianshu Tian, Hongyan Wang, Zhongyuan Huang, Renguo Lu, Peihong Cong, Xujun Liu, Tongsheng Li

    Journal of Macromolecular Science, Part B: Physics   49: 791-801   2010.6

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  • Effect of Lubricant Additives on Tribochemical Decomposition of Hydrocarbon Oil on Nascent Steel Surfaces Reviewed

    LU Renguo, NANAO Hidetaka, KOBAYASHI Kimihiro, KUBO Tomoo, MORI Shigeyuki

    Bulletin of The Japan Petroleum Institute   53 (1), 55-60 ( 1 )   55 - 60   2010.1

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    Language：English   Publisher：The Japan Petroleum Institute  

    A nascent surface has high activity to catalyze the decomposition of lubricants under boundary lubrication conditions. The effects of sulfur-containing, nitrogen-containing, phosphorus-containing additives and phosphate-containing ionic liquid were investigated on the decomposition of synthetic hydrocarbon oil (multialkylated cyclopentane, MAC). The decomposition processes of the lubricants on the nascent surface of bearing steel AISI 52100 were investigated using a ball-on-disk friction tester in a vacuum chamber with a quadrupole mass spectrometer. Three parameters related to the decomposition process were observed: the induction period for the decomposition, the desorption rate of gaseous products, and the critical load for the activation of the decomposition. The order of efficiency of additives in extending the induction period was: sulfur-containing additive (S)<nitrogen-containing additive (N)<phosphorus-containing additive (P)<phosphate-containing ionic liquid (P-IL). The order of efficiency in increasing the critical load was: N<S<P<P-IL, and the order of efficiency in decreasing the decomposition rate was: N<S<P<P-IL. These results suggest that additives which can form iron salts (such as iron phosphate and iron sulfide) will deactivate the nascent surface, decreasing the decomposition rate and increasing the critical load.

    DOI： 10.1627/jpi.53.55

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  • Effect of sulfur-containing additive on decomposition of multialkylated cyclopentane oil on the nascent steel surface Reviewed

    Renguo Lu, Shigeyuki Mori, Tomoo Kubo, Hidetaka Nanao

    Wear   267: 1430-1435   2009.9

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  • Study of Tribochemical Decomposition of Ionic Liquids on a Nascent Steel Surface Reviewed

    LU R.

    Applied Surface Science   255: 8965-8971 ( 22 )   8965 - 8965   2009.8

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  • Deactivation effect of tricresyl phosphate (TCP) on tribochemical decomposition of hydrocarbon oil on nascent steel surface Reviewed

    Renguo Lu, Kimihiro Kobayashi, Hidetaka Nanao, Shigeyuki Mori

    Tribology Letters   33: 1-8   2009.1

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  • Study on Decomposition of Multialkylated Cyclopentane Oil with Sulfur-Containing Additive on the Nascent Steel Surface Reviewed

    Lu Renguo, Mori Shigeyuki, Nanao Hidetaka, Kobayashi Kimihiro, Minami Ichiro

    Tribology Online   2: 105-109 ( 4 )   105 - 109   2007.11

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    Language：English   Publisher：Japanese Society of Tribologists  

    Effect of di-tert-dodecyl disulfide as an additive on decomposition of MAC oil on the nascent surface of bearing steel 52100 was investigated. After the removal of surface contamination layer, active sites were generated, on which tribochemical decomposition of MAC oil occurred. The additive prolonged the induction period of the decomposition. Hydrogen and gaseous hydrocarbons desorbed as tribochemical reaction products. Desorption rate of hydrogen and gaseous hydrocarbons increased proportionally with sliding velocity and linearly with the cube root of load. XPS analysis revealed tribochemical reaction between additive and nascent surface occurred, which induced formation of iron sulfide and decrease of activity of nascent surface. As a result, decomposition of MAC oil decreased correspondingly.

    DOI： 10.2474/trol.2.105

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  • Investigation of decomposition of hydrocarbon oil on the nascent surface of steel Reviewed

    Renguo Lu, Ichiro Minami, Hidetaka Nanao, Shigeyuki Mori

    Tribology Letters   27: 25-30   2007.2

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MISC

  • トライボトロニクス

    小金沢新治, 谷弘詞, 呂仁国, 多川則男

    技苑   ( 150 )   2020

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  • トライボロジー分野の工学実験―転がり軸受の摩擦・摩耗

    呂仁国,谷弘詞

    2017.5

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  • 顕微FT-IRを用いたトライボロジー現象のその場観察

    呂仁国

    2015.11

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    Publisher：理工学と技術  

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Presentations

  • In-situ Observation of Electric-Current-Induced Decomposition of Lubricants

    Kento Imai, Renguo Lu, Shohei Kawada, Hiroshi Tani, Shinji Koganezawa

    9th International Tribology Conference (ITC Fukuoka 2023)  2023.9 

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    Event date： 2023.9

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  • In-situ Observation of Electric-Field-Driven Behavior of Lubricant Molecules

    Chencheng Wu, Kazufumi Kontani, Renguo Lu, Shohei Kawada, Hiroshi Tani, Shinji Koganezawa

    9th International Tribology Conference (ITC Fukuoka 2023)  2023.9 

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  • Adsorption and Tribological Properties of Perfluoropolyether Lubricant Films Having Main-Chains With Different Carbon Number

    Hiroshi Tani, Yuki Yamaji, Ryosuke Sagata, Tomomi Hatta, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    The 32nd ASME Annual Conference on Information Storage and Processing Systems (ISPS 2023)  2023.8 

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  • Effect of Humidity on Head Smear Generation in Head Assisted Magnetic Recording

    H. Tani, H. Kurafuji, N. Tagawa, S. Kawada, R. Lu, S. Koganezawa

    2023 IEEE International Magnetic Conference  2023.5 

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  • Feasibility study of reduction in sound-pressure induced vibration in hard disk drives using an adaptive feed-forward control

    Shinji Koganezawa, Kensei Funai, Hiroshi Tani, Renguo Lu, Shohei Kawada

    2023 IEEE International Magnetic Conference  2023.5 

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  • Improvement of self-powered vibration sensing device for structural health monitoring

    Saho Ikeda, Masaya Hatanaka, Shinji Koganezawa, Shohei Kawada, Renguo Lu, Hiroshi Tani, Norio Tagawa

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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  • Elastic Modulus Measurement of Ultrathin Diamond-Like Carbon Film Using Gas Cluster Ion Beam

    Norio Tagawa, Hiroshi Tani, Shinji Koganezawa, Renguo Lu

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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  • Effects of Oxygen Concentration on Smear Formation in HAMR System

    Kenji Yakata, Hiroshi Kurafuji, Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Shouhei Kawada, Norio Tagawa

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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  • External electric field effect to head smear generated from disk with PFPE lubricant film in heat-assisted magnetic recording

    Hiroshi Tani, Makoto Toyoda, Shouhei Kawada, Renguo Lu, Shinji Koaganezawa, Norio Tagawa

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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  • Monitoring radial load force of rolling bearing using triboelectric sensor

    Yuya Tone, Hiroshi Tani, Shinji Koganezawa, Renguo Lu, Shohei Kawada

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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    Event date： 2022.8

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  • Estimation of tire wear using multiple tribocharge sensors mounted inside tire

    Koki Hosoda, Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Shohei Kawada, Norio Tagawa, Takahiro Fujiwara, Kyota Sugioka, Kenichi Kuroda, Mutsuki Sugimoto, Yukio Nakao

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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    Event date： 2022.8

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  • Development of counting system of people passing on floor mat using triboelectric power generation

    Ryo Kawakami, Hiroshi Tani, Shohei Kawada, Rengo Lu, Shinji Koganezawa, Norio Tagawa

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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    Event date： 2022.8

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  • An inclined-legs actuator inspired by Setaria viridis

    Hotaka Tsuboi, Shinji Koganezawa, Hiroshi Tani, Renguo Lu, Shohei Kawada

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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    Event date： 2022.8

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  • Relationship between lubricating properties and relative humidity under lubrication with ionic liquids

    Shouhei Kawada, Shunsuke Tanji, Jyo Kobayashi, Masaaki Miyatake, Shinya Sasaki, Renguo Lu, Shinji Koganezawa, Hiroshi Tani

    THE 22ND INTERNATIONAL VACUUM CONGRESS (IVC-22)  2022.9 

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  • EFFECT OF ELECTRIC CURRENT ON FRICTION BEHAVIOR OF LUBRICANT MOLECULES

    Renguo Lu, Kazufumi Kontani, Hiroshi Tani, Shohei Kawada, Shinji Koganezawa,Norio Tagawa

    2022 JSME-IIP/ASME-ISPS Joint International Conference on Micromechatronics for Information and Precision Equipment (MIPE2022)  2022.8 

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    Venue：Nagoya  

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  • Development of vibration sensor using giant magnetostrictive material for self-powered structural health monitoring system

    Shinji Koganezawa, Tomotake Ishii, Hiroshi Tani, Renguo Lu, Norio Tagawa,

    2020.10 

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  • Investigation of smear formation mechanism from DLC film by heating

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    2020.6 

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  • Energy harvesting from triboelectric nanogenerator attached inside rolling tire

    Hiroshi Tani, Mutsuki Sugimoto, Kazuhisa Fushihara, Yukio Nakao, Renguo Lu, Shinji Koganezawa,

    2019.12 

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  • Effect of laser heating on the smear behavior of PFPE lubricant films on magnetic disks in air and helium

    Norio Tagawa,Kenji Yakata,Hiroshi Tani,Shinji Koganezawa,Renguo Lu

    2019.11 

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  • Tribofilm characterization by surface enhanced Raman spectroscopy

    Hiroshi Tani, Kyohei Kijima, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    2019.10 

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  • Study of Hydrogen Diffusion in Bearing Steel and the Segregation Effect of DLC

    Renguo Lu, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    International Conference on Mechanical Design and History of Technology 2019 (ICMDHT-2019)  2019.9 

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    Venue：Osaka, Japan  

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  • Revoluton speed monitoring of retainer in bearing using tribocharge sensor

    Hiroshi Tani, Daiki Okishio, Lu Rengo, Shinji Koganezawa, Norio Tagawa

    International Tribology Conference Sendai 2019 (ITC Sendai2019)  2019.9 

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    Venue：Sendai, Japan  

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  • Smear and decomposition behaviors of PFPE lubricant film on magnetic disk by laser heating in air and helium

    Kenji Yakata,Satoki Ichikawa,Koji Otawa,Hiroshi Tani,Renguo Lu,Shinji Koganezawa,Norio Tagawa

    International Tribology Conference Sendai 2019 (ITC Sendai2019)  2019.9 

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    Venue：Sendai, Japan  

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  • A Study of diffusion and segregation of hydrogen in bearing steels

    Renguo Lu, Sora Shiode, Takayuki Hamada, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa,

    2019.9 

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  • Study of hydrogen diffusion in bearing steel and the segregation effect of DLC

    Renguo Lu, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    2019.9 

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  • A STUDY OF DIFFUSION AND SEGREGATION OF HYDROGEN IN BEARING STEELS

    Renguo Lu, Sora Shiode, Takayuki Hamada, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    International Tribology Conference Sendai 2019 (ITC Sendai2019)  2019.9 

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    Venue：Sendai, Japan  

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  • Hybrid lubricant film with high bonding ratio and high coverage

    Hiroshi Tani,Yuki Uesaraie,Renguo Lu,Shinji Koganezawa,Norio Tagawa

    2019.6 

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  • Smear behavior of PFPE lubricant films on magnetic disk by laser heating in air and helium

    Norio Tagawa,Kenji Yakata,Hiroshi Tani,Renguo Lu,Shinji Koganezawa

    2019.6 

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  • Tribological Properties of Phenylethers in Boundary Lubrication

    Renguo Lu, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa,

    The European Conference on Tribology 2019 (ECOTRIB 2019)  2019.6 

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    Venue：Vienna, Austria  

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  • Tribological properties of phenylethers in boundary lubrication

    Renguo Lu, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    2019.6 

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  • PFPE Lubricant Film with High Thermal Stability Deposited by Photoelectron Assisted Chemical Vapor Deposition

    Hiroshi Tani, Lu Rengo, Shinji Koganezawa, Norio Tagawa

    2018 Asia-Pacific Magnetic Recording Conference (APMRC)  2018.11 

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    Venue：Shanghai, China  

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  • PFPE lubricant film with high thermal stability deposited by photoelectron assisted chemical vapor deposition

    Hiroshi Tani, Rengo Lu, Shinji Koganezawa, Norio Tagawa

    2018.11 

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  • Organic liquid generated from DLC during laser heating

    Hiroshi Tani,Yuta Shibahara,Yuki Uesaraie,Renguo Lu,Shinji Koganezawa,Norio Tagawa

    2018.10 

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  • Organic Liquid Generated from DLC during Laser Heating

    Hiroshi Tani,Yuta Shibahara,Yuki Uesaraie,Renguo Lu,Shinji Koganezawa,Norio Tagawa

    2018TFC  2018.10 

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    Venue：Chicago, USA  

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  • Friction reduction of SiC mechanical seal by carbon nanofiber film

    D. Okishio, H. Tani, R. Lu, S. Koganezawa, N. Tagawa

    The 6th Asia International Conference on Tribology,  2018.9 

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    Venue：Sarawak, Malaysia  

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  • Effect of DLC coating on preventing hydrogen diffusion in thrust bearing

    Renguo Lu, Sora Shiode, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    2018.9 

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  • Effect of DLC Coating on Preventing Hydrogen Diffusion in Thrust Bearing

    Renguo Lu, Sora Shiode, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    The 6th Asia International Conference on Tribology  2018.9 

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    Venue：Sarawak, Malaysia  

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  • Numerical study on the effects of linear protrusion on flow-induced carriage excitation force in hard disk drives

    Shinji Koganezawa,Shotaro Tsuda,Hiroshi Tani,Renguo Lu, Norio Tagawa

    2018.8 

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  • TOF-SIMS analysis of accumulated PFPE lubricant smear following laser heating

    Hiroshi Tani,Yuta Shibahara,Shinji Koganezawa,Renguo Lu,Norio Tagawa

    2018.8 

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  • Study of lubricant depletion induced by pulsed-laser irradiation heating in heat-assisted magnetic recording

    Norio Tagawa,Hiroshi Tani,Yuki Uesaraie,Shinji Koganezawa,Renguo Lu

    2018.8 

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  • STUDY OF LUBRICANT DEPLETION INDUCED BY PULSED-LASER IRRADIATION HEATING IN HEAT-ASSISTED MAGNETIC RECORDING

    Norio Tagawa,Hiroshi Tani,Yuki Uesaraie,Shinji Koganezawa,and Renguo Lu

    the ASME-JSME 2018 Joint International Conference on Information Storage and Processing Systems and Micromechatronics for Information and Precision Equipment  2018.8 

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    Venue：San Francisco,CA,USA  

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  • TOF-SIMS ANALYSIS OF ACCUMULATED PFPE LUBRICANT SMEAR FOLLOWING LASER HEATING

    Hiroshi Tani,Yuta Shibahara,Shinji Koganezawa,Renguo Lu,Norio Tagawa

    the ASME-JSME 2018 Joint International Conference on Information Storage and Processing Systems and Micromechatronics for Information and Precision Equipment  2018.8 

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    Venue：San Francisco,CA,USA  

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  • NUMERICAL STUDY ON THE EFFECTS OF LINEAR PROTRUSION ON FLOW-INDUCED CARRIAGE EXCITATION FORCE IN HARD DISK DRIVES

    Shinji Koganezawa,Shotaro Tsuda,Hiroshi Tani,Renguo Lu, Norio Tagawa

    the ASME-JSME 2018 Joint International Conference on Information Storage and Processing Systems and Micromechatronics for Information and Precision Equipment  2018.8 

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    Venue：San Francisco,CA,USA  

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  • Nanoscale wear of carbon overcoat subjected to laser heating in an inert gas environment

    Norio Tagawa,Hiroshi Tani,Shinji Koganezawa,Renguo Lu

    2018.7 

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  • Nanoscale Wear of Carbon Overcoat Subjected to Laser Heating in an Inert Gas Environment

    Norio Tagawa,Hiroshi Tani,Shinji Koganezawa,Renguo Lu

    the 7th International Conference on Fracture Fatigue and Wear  2018.7 

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    Venue：Gent University, Belgium  

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  • Insect-sized flapping-flight robot using dry friction–based self-excited vibration

    Shinji Koganezawa, Takahiro Fujiwara, Taiki Usami, Ryo Kawasaka, Renguo Lu, Hiroshi Tani, Norio Tagawa

    Euspen’s 18th International Conference & Exhibition  2018.6 

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    Venue：Venice, IT  

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  • Study of the hydrogen diffusion and segregation into thrust bearing steel using TOF-SIMS

    Renguo Lu, Hiroshi Tani, Norio Tagawa and Shinji Koganezawa

    2018.6 

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  • Study of the Hydrogen Diffusion and Segregation into Thrust Bearing Steel Using TOF-SIMS

    Renguo Lu, Hiroshi Tani, Norio Tagawa and Shinji Koganezawa

    The 18th Nordic Symposium on Tribology (Nordtrib2018)  2018.6 

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    Venue：Uppsala, Sweden  

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  • Molecularly structural change of PFPE lubricant accumulated on pin surface at laser heating

    H. Tani, Y. Shibahara, R. Lu, S. Koganezawa, N. Tagawa

    2018.5 

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  • Molecularly Structural Change of PFPE Lubricant Accumulated on Pin Surface at Laser Heating

    H. Tani, Y. Shibahara, R. Lu, S. Koganezawa, N. Tagawa

    Intermag 2018  2018.5 

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    Venue：Singapore  

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  • カルボン酸の低摩擦特性に及ぼす分子配向の影響

    呂 仁国、谷 弘詞、小金沢 新治、多川 則男

    関西大学先端科学技術シンポジウム  2018.1 

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    Venue：関西大学  

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  • Adsorption Properties of an Ultrathin PFPE Lubricant with Ionic End-groups for DLC Surfaces

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    Eighth Advanced Forum on Tribology 2017  2017.9 

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    Venue：Zhenjiang China  

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  • In situ Micro-FTIR Spectroscopic Observation on Shear-induced Molecular Orientation of Carboxylic Acids

    Renguo Lu,Shigeyuki Mori,Hiroshi Tani,Norio Tagawa,and Shinji Koganezawa

    World Tribology Congress 2017  2017.9 

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    Venue：Beijing,China  

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  • Observation of Tribofilm Growth and Friction Coefficient Microscopy of Tribofilms

    Sora Shiode,Renguo Lu,Hiroshi Tani,Norio Tagawa,and Shinji Koganezawa

    World Tribology Congress 2017  2017.9 

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    Venue：Beijing,China  

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  • SMEAR GROWTH OF SILOXANE OUTGAS AT LASER HEATING

    Hiroshi Tani,Norio Tagawa,Shinji Koganezawa,Renguo Lu

    the ASME 2017 Conference on Information Storage and Processing Systems  2017.8 

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    Venue：San Francisco,California,USA  

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  • Adsorption Properties of an Ultrathin PFPE Lubricant with Ionic End-groups for DLC Surfaces

    Hiroshi Tani, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    The 28th Magnetic Recording Conference 2017  2017.8 

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    Venue：Tsukuba Japan  

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  • EFFECT OF LASER HEATING ON NANOSCALE WEAR OF DLC THIN FILMS IN AN AIR ENVIRONMENT

    Norio Tagawa,Hiroshi Tani,Shinji Koganezawa,Renguo Lu

    the ASME 2017 Conference on Information Storage and Processing Systems  2017.8 

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    Venue：San Francisco,California,USA  

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  • A Study on Tribofilm Growth and the Friction Coefficient Microscopy

    Renguo Lu, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    6th European COnference on TRIBology（ECOTrib2017）  2017.6 

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    Venue：Ljubljana(Slovenia)  

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  • 境界潤滑におけるカルボン酸会合体摩擦特性の温度依存性

    塩出 空,呂 仁国,谷 弘詞,多川 則男,小金沢 新治,森 誠之

    トライボロジー会議2017東京  2017.5 

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    Venue：東京  

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  • Wear of Carbon Overcoat Subjected to Laser Heating in an Inert Gas Environment During Heat-assisted Magnetic Recording

    Norio Tagawa, Hiroshi Tani,Yusuke Hata, Shinji Koganezawa, Renguo Lu

    2016 STLE Tribology Frontiers Conference PROGRAM GUIDE  2016.11 

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    Venue：Chicago U.S.A  

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  • Tribological Properties of Carbon Nano-fiber Film on SiC Surface

    Hiroshi Tani, Masahiro Yamashita, Renguo Lu, Shinji Koganezawa, Norio Tagawa

    2016 STLE Tribology Frontiers Conference PROGRAM GUIDE  2016.11 

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    Venue：Chicago U.S.A  

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  • Low Friction Properties of Associated Carboxylic Acids Induced by Molecular Orientation

    Renguo Lu, Shigeyuki Mori, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    43rd Leeds-Lyon Symposium on Tribology  2016.9 

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    Venue：Leeds, UK  

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  • Ultrathin PFPE/DLC Hybrid Overcoat for Magnetic Disks by Photoelectron-assisted Chemical Vapor Deposition

    Hiroshi Tani, Lu Renguo, Shinji Koganezawa, Norio Tagawa

    2016 Digest APMRC  2016.7 

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    Venue：Korea  

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  • Decomposition of perfluoropolyether lubricant picked up on actual air bearing surface in heat-assisted magnetic recording

    Norio Tagawa, Hiroshi Tani, Hiroaki Asada, Renguo Lu and Shinji Koganezawa

    2016 Digest APMRC  2016.7 

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    Venue：Korea  

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  • Effect of Molecular Orientation on Friction Properties of Associated Carboxylic Acids

    Sora Shiode, Renguo Lu, Shigeyuki Mori, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    The 7th Advanced Forum on Tribology  2016.4 

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    Venue：Nara, Japan  

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  • Tribochemical Reaction and Tribofilm Formation on Friction-Activated Steel Surfaces

    Renguo Lu, Hiroshi Tani, Norio Tagawa, Shinji Koganezawa

    EMN Meeting on Suraface and Interface  2016 

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    Venue：12-16 Sep 2016, Kuala Lumpur, Malaysia  

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  • Tirbochemical Decomposition of Synthetic Oils under a High Vacuum Condition: Part 2，Effect of Surface Roughness

    Koji Takiwatari,Renguo Lu,Hidetaka Nanao,Shigeyuki Mori,Yoshinori Fukushima,Youichi Murakami,Shozo Ikejima,Tadaaki Konno

    the International Tribology Conference 2015 Tokyo  2015.9 

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    Venue：Tokyo, Japan  

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  • Tirbochemical Decomposition of Synthetic Oils under a High Vacuum Condition: Part 1，Induction Period for the Decomposition

    Renguo Lu,Hidetaka Nanao,Koji Takiwatari,Shigeyuki Mori,Yoshinori Fukushima,Youichi Murakami,Shozo Ikejima,Tadaaki Konno

    the International Tribology Conference 2015 Tokyo  2015.9 

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    Venue：Yokyo, Japan  

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Awards

  • Best Paper Award

    2023.8   ASME ISPS Division   Adsorption and Tribological Properties of Perfluoropolyether Lubricant Films Having Main-Chains with Differrent Carbon Number

    Hiroshi Tani, Yuki Yamaji, Ryosuke Sagata, Tomomi Hatta, Renguo Lu, Shinji Koganezawa, Norio Tagawa

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  • 日本機械学会関西支部賞（研究賞）

    2023.3   日本機械学会関西支部   Arガスクラスターイオンビームを用いた超薄膜弾性率の測定手法の確立

    谷弘詞;呂仁国;小金沢新治;多川則男;清水豪

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  • Best Paper Award

    2020.6   ASME ISPS Division   Investigation smear formation mechanism from DLC film by heating

    Hiroshi Tani, Renguo Lu, Shinji koganezawa, Norio Tagawa

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  • Best Paper Award

    2019.6   ASME ISPS Division   Hybrid Lubricant Film with High Bonding Ratio and High Coverage

    Hiroshi Tani, Yuki Uesaraie, Renguo Lu, Shinji Koganezawa, Norio Tagawa

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Research Projects

  • Improvement of triboelectricf power generator output and study of tribological phenomena in large electricfield

    Grant number：21H01240  2021.4 - 2024.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (B)

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    Authorship：Coinvestigator(s) 

    Grant amount：\17680000 （ Direct Cost: \13600000 、 Indirect Cost：\4080000 ）

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  • Electric Field Effects on the Tribological Properties of Lubricants

    Grant number：20K04247  2020.4 - 2023.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

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    Authorship：Principal investigator 

    Grant amount：\4290000 （ Direct Cost: \3300000 、 Indirect Cost：\990000 ）

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  • Study on hydrogen diffusion in steels induced by tribochemical decomposition of lubricants and the depression effect of DLC coatings on hydrogen diffusion

    Grant number：17K06130  2017.4 - 2020.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

    Lu Renguo

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    Authorship：Principal investigator 

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

    Bearing failure is often accompanied by hydrogen embrittlement, which was caused by hydrogen diffusion in steel. The aim of this project was to declare the effect of DLC coating on preventing hydrogen diffusion. Deuterated lubricants were used to discriminate between the original hydrogen in steel and the hydrogen generated from lubricant decomposition. After friction tests of thrust bearings, the deuterium distribution on the cross section of the raceway was analyzed using Tof-SIMS. The highest concentration of deuterium was always near the raceway surface, and the concentration decreased gradually as the depth was increased. To protect steels against the ingress of hydrogen, the effect of DLC coating, which has a low diffusion coefficient of hydrogen, was studied. DLC reduced but did not completely prevent the ingress of hydrogen, which resulted from the reduction in the amount of hydrogen generated from the tribochemical and thermal decomposition of lubricants.

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  • Micro- and nano-tribological properties of tribofilms

    Grant number：15H06748  2015.8 - 2017.3

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Research Activity Start-up

    Lu Renguo, SHIODE Sora, NISHITANI Akira, CHIKAI Keisuke

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    Authorship：Principal investigator 

    Grant amount：\2990000 （ Direct Cost: \2300000 、 Indirect Cost：\690000 ）

    In boundary lubrication, tribofilms are crucial for the management of wear and control of friction. Although a significant progress has been obtained in understanding the mechanisms of the tribofilms, the tribological properties were measured in the presence of lubricants. Strictly speaking, the measured friction forces were not the tribofilms, but the lubricants. This study focused on the tribological properties of tribofilms to make clear their antiwear and low friction mechanisms.
    Using an AFM, the tribofilms’ growth were studied. Periodic changes in film thickness were observed, suggesting that the tribofilm should be generated in a dynamic process of formation and destruction. Using a self-developed friction tester, the friction coefficient distribution was firstly obtained in a larger area. The friction coefficient in micro-scale did not depend on the surface morphology, but agreed well to the chemical images of the tribofilms.

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Teaching Experience

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