RYU Gyogyoku

写真a

Affiliation Department etc.

Department of Electrical and Mechanical Engineering
Department of Electrical and Mechanical Engineering

Title

Assistant Professor

Mail Address

E-mail address

Homepage URL

http://tribo.web.nitech.ac.jp/

Research Fields, Keywords

tribology, carbonaceous hard coating, laser processing

Graduate School

  • 2012.08
    -
    2015.07

    Tsinghua University  Graduate School, Division of Engineering  Enviromental EngineeringMaster's Course  Completed

Degree

  • Nagoya University -  Doctor (Engineering)

  • Tsinghua University -  Master (Engineering)

Academic Society Affiliations

  • 2019.10
    -
    Now

    OSA (The optical society)

Field of expertise (Grants-in-aid for Scientific Research classification)

  • Materials/Mechanics of materials

  • Design engineering/Machine functional elements/Tribology

  • Production engineering/Processing studies

 

Papers

  • Tribological properties of ta-CNx coating sliding against steel and sapphire in unlubricated condition

    Xiaoxu Liu, Noritsugu Umehara, Takayuki Tokoroyama, Motoyuki Murashima

    Tribology International ( Elsevier )  131   102 - 111   2018.10  [Refereed]

    Research paper (scientific journal)   Single Author

  • Effect of oil temperature and counterpart material on the wear mechanism of ta-CNx coating under base oil lubrication

    Xiaoxu Liu, Ryo Yamaguchi, Noritsugu Umehara, Motoyuki Murashima, Takayuki Tokoroyama

    Wear ( Elsevier )  390   312 - 321   2017.09  [Refereed]

    Research paper (scientific journal)   Multiple Authorship

    Tetrahedral amorphous carbon nitride (ta-CNx), as an emerging and promising diamond-like carbon (DLC), has better mechanical properties than amorphous carbon nitride (a-CNx) to ensure the sufficient durability, and overcomes the limit of high internal stress of tetrahedral amorphous carbon (ta-C), which makes ta-CNx coatings ofgreatworthofresearchforthetribologicalandmechanicalapplications.Inthisstudy,wepresenttheeffectsof oil temperature and counterpart material on the wear behavior of ta-CNx coatings under base-oil lubrication, andfurtherclarifythewearmechanism.ta-Candta-CNxcoatingswithN/Catomicratioof2.2%and11.0%were deposited by an ion beam assisted filtered arc deposition (IBA-FAD) system, and the tribological tests were performed using a ball-on-disk tribo-tester with ta-C and ta-CNx coated steel ball sliding against uncoated disk under base-oil lubrication. The results show that nitrogen doping tends to decrease the hardness and Young's modulus by reducing the sp3 structure. Sliding against steel disk, with increase of sliding distance ta-CNx shows obviously distinct wear behavior compared to ta-C, much more slowly increasing wear volume, exhibiting excellent wear resistance. Increasing oil temperature from room temperature to 120 °C results in rising wear rates of all the three coatings, with totally worn out ta-C and much lower wear rate of ta-CNx, which decreases by more than half than ta-C for high nitrogen content ta-CNx. However, as the counterpart material changed from steel to alumina, the wear rate presents oppositely increasing tendency with N/C ratio, probably caused by the change of deciding factor to hardness in this mechanical wear. It is found that the wear performance of ta-CNx coating has a clear dependence on the oil temperature and counterpart material. Based on the results, the better wear resistance of softer ta-CNx against steel could be attributed to the less tribo-chemical wear between carbon and iron, due to the nitrogen doping partial passivation effect.

  • Clarification of high wear resistance mechanism of ta-CNx coating under poly alpha-olefin (PAO) lubrication

    Xiaoxu Liu RyoYamaguchi NoritsuguUmehara Xingrui Deng Hiroyuki Kousaka Motoyuki Murashima

    Tribology International ( Elsevier )  105   193 - 200   2016.10  [Refereed]

    Research paper (scientific journal)   Multiple Authorship

Presentations

  • Femtosecond Laser Processing of CVD Diamond Coated Cutting Tool Edge

    Xiaoxu Liu, Kohei Natsume, Satoru Maegawa, Fumihiro Itoigawa, Shingo Ono and Michiharu Ota

    the 15th China-Japan International Conference on Ultra-Precision Machining Process (CJUMP)  (群馬県前橋市)  2019.09  -  2019.09  精密工学会ナノ精度機械加工専門委員会、中国机械工程学会

  • Pulse Laser Grinding Processing of Polycrystalline CVD Diamond Coated Cutting Tool Edge with Femtosecond Laser

    Xiaoxu Liu, Kohei Natsume, Satoru Maegawa, Fumihiro Itoigawa

    FIO/LS: Frontiers in Optics + Laser Science 2019  (Washington District of Columbia, USA)  2019.09  -  2019.09  OSA, The optical society

  • Tool edge shaping of CVD diamond coated tool with ultra -short pulse laser

    (Akita University)  2019.09  -  2019.09  JSME

  • A Comparative Study of Surface Modification effects of Femtosecond and Nanosecond Laser on CVD Diamond Tools during Sharpening Processing

    Xiaoxu Liu, Kohei Natsume, Satoru Maegawa, Fumihiro Itoigawa, Shingo Ono and Michiharu Ota

    CLEO: Laser Science to Photonic Application  (San Jose Convention Center, San Jose, California, USA)  2019.05  -  2019.05  OSA, The optical society

  • Surface modification of polycrystalline CVD diamond films with femtosecond laser

    Kohei Natsume, Xiaoxu Liu, Satoru Maegawa, Fumihiro Itoigawa, Shingo Ono and Michiharu Ota

    CLEO: Laser Science to Photonic Application  (San Jose Convention Center, San Jose, California, USA)  2019.05  -  2019.05  OSA, The optical society

  • Micromachining of Polycrystalline CVD Diamond Coated Cutting Tool with Femtosecond Laser

    Xiaoxu Liu, Kohei Natsume, Satoru Maegawa, Fumihiro Itoigawa

    The 8th International Conference on Manufacturing, Machine Design and Tribology (ICMDT2019)  (鹿児島)  2019.04  -  2019.04  日本機械学会 韓国機械学会

  • Clarification of high wear resistance of ta-CNx coating under base-oil lubrication

    Liu, X., Umehara, N., Tokoroyama, T, Murashima, M.

    トライボロジー会議2018秋 伊勢  2018.11  -  2018.11  日本トライボロジー学会

  • Tribological properties of ta-CNx coating under different oil temperatures and counterpart materials in base oil

    Liu, X., Umehara, N., Tokoroyama, T, Murashima, M.

    6th World Tribology Congress - WTC  (Beijing (China))  2017.09  -  2017.09 

  • Wear behavior of tetrahedral amorphous carbon nitride under poly alpha-olefin (PAO) lubrication

    Liu, X., Yamaguchi, R., Umehara, N., Murashima, M,

    4th International Conference on Manufacturing, Machine Design and Tribology - ICMDT  (Jeju (Korea))  2017.04  -  2017.04  JSME, KSME

  • Mechanical and tribological properties of ta-CNx coatings prepared by filtered arc deposition

    Liu, X., Umehara, N., Deng, X., Kousaka,H,

    5th International Conference on INTEGRITY RELIABILITY FAILURE - IRF  (Porto (Portugal))  2016.07  -  2016.07 

Other external funds procured

  • Offer organization: Private Foundations 

    Project Year: 2019.03  -  2019.09