Dr. Noritsugu Umehara
Professor,
Department of Micro-Nano Mechanical Science and Engineering,
Graduate School of Engineering,
Nagoya University.
Department of Micro-Nano Mechanical Science and Engineering,
Graduate School of Engineering,
Nagoya University.
Biography
Dr. Noritsugu Umehara is a professor at the Department of Micro-nano Mechanical Science and Engineering, Nagoya University in Japan. He has interests in both fundamental and applied aspects of manufacturing and tribology, especially in the new polishing method of advanced ceramic using a magnetic field and water lubrication of advanced ceramics. He started his career at the Tohoku University in 1988 as a Research Associate at the Department of Mechanical Engineering before becoming Assistant Professor in 1993, Associate Professor in 1995, and moved to Nagoya University as Professor in 2003. He received a Bachelor's degree, a Master's degree and a Doctor of Engineering from the University of Tohoku, Sendai, Miyagi in 1983, 1985 and 1988. He has published more than 200 research papers in different journals and holds 6 patents on magnetic fluid grinding. Dr. Umehara received the JSME Young Engineering Award in 1991, 1995 LaRoux K. Gillespie Outstanding Young Manufacturing Engineer Award from the Society of Manufacturing Engineers in 1995, the F.W. Tayler Medal of the CIRP in 1995, and the 2010 JSME paper award. He is a member of the Japan Society of Mechanical Engineers (JSME), the Japan Society for Precision Engineering (JSPE), the Japan Society of Tribologists (JAST), and the Japan Society for Grinding. He is the Editorial Board Member of the Journal of Engineering Tribology, Proceedings of the Institution of Mechanical Engineers, Part J; Friction; Springer; and Jurnal Tribologi, Malaysian Tribology Society.
In-situ Observation of Friction Surface with Reflectance Spectroscopy
Reflectance spectroscopy can obtain the optical properties as reflective index and extinction coefficient, and the thickness of each layer in the multilayer optical model for contact surface. So we can analyze the properties of transformed layer and oil film. The carbonaceous coating such as Diamond-Like Carbon (DLC) coating and amorphous Carbon Nitride (CNx) coating is promising for high hardness, low friction property and affordability. Though it is reported that transformed layer is important to show low friction, it is still unclear that transformed layer makes an effect on low friction. To clarify the effect of transformed layer of CNx on friction clearly, we proposed the in-situ observation method which observe the friction surface with a reflectance spectroscopy and measures friction force simultaneously. The reflectance spectrometer was set above the sapphire hemisphere attached at leaf spring so that reflectance spectrometer could measure the thickness, sp2/sp3 ratio and density of dangling bonds of the coating through sapphire hemisphere. From the result, it can be seen that estimated friction coefficients follow observed friction coefficients. Also this in-situ observation method with a reflectance spectroscopy was tried to use to know the condition of two phase lubricants which is the mixture of two lubricants. The two phase lubricants consist of the low and high viscosity base oils which are miscible at high temperature but not at lower temperature. However it is difficult to know the separation condition in the thin lubricant film during sliding. Experimental results showed the possibility of the separation of two lubricant in lubricant film with the reflectance spectroscopy.