“Frictionless” Diamond-Like Coatings and In-Situ Observation using Reflectance Spectroscopy

Thursday, October 24, 2019

5 King's College Rd.


This event is open to the public and registration is not required.

Special MIE seminar with Dr. Noritsugu Umehara, Department of Micro-Nano Mechanical Science and
Engineering, Nagoya University, Japan




Carbonaceous coatings, such as Diamond-Like Carbon (DLC) coating and amorphous Carbon Nitride (CNx) coating offer high hardness, low friction property and are affordable. Though it is reported in the literature that the transformed layer plays an important role in friction reduction, it is still unclear the mechanism(s) by which this low friction is developed.

Reflectance spectroscopy provides optical properties in the form of reflective index and extinction coefficient, as well as the thickness of each layer in a multilayer surface. This would allow us to analyze the properties of the transformed layer and the associated oil film. Specifically, in order to establish the effect of the transformed layer of CNx on friction, we developed novel in-situ observation technique using reflectance spectroscopy. The newly adopted reflectance spectroscopy technique facilitated the determination of the friction characteristics and allowed us to measures the friction force simultaneously. The reflectance spectrometer was set up appropriately to enable us measure the thickness, sp²/sp³ ratio and density of dangling bonds of the coating through sapphire hemisphere arrangement.

Our results reveal the reliability of our measurements technique as compared with our earlier works and other works that exists in the literature that estimate the friction coefficient. Additionally, this in-situ observation method with our reflectance spectroscopy was used to study the condition of two-phase lubricants, which is a mixture of two lubricants. Two-phase lubricants consist of low and high viscosity base oils, which are miscible at higher temperatures but not so at lower temperatures. However, it is difficult to know the separation condition in the thin lubricant film during sliding. We succeeded in measuring the separation of two lubricants in lubricant film using our reflectance spectroscopy.




Dr. Noritsugu Umehara is a professor in the Department of Micro-Nano Mechanical Science and Engineering at Nagoya University, Japan. He has interests in both fundamental and applied aspects of manufacturing and tribology, especially in new polishing method of advanced ceramic materials using magnetic field and water lubrication.

He received his Bachelor, Master and a Doctorate of Engineering from Tohoku University, Sendai, Miyagi in 1983, 1985 and 1988, respectively. He began his carrier at Tohoku University in 1988 as a Research Associate in the Department of Mechanical Engineering prior to becoming Assistant Professor in 1993, Associate Professor in 1995. Professor Umehara joined Nagoya University as Professor in 2003. He publishes extensively in the relevant materials, manufacturing and tribology journals, and his scholarly work led to 6 Patents on Magnetic Fluid Grinding. He is regularly invited to give plenary and keynote lectures in international meetings and consults for the Japanese automotive industry. He directs the Advanced Manufacturing Laboratory in Nagoya University.

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; F.W. Tayler Medal from the CIRP in 1995; and JSME paper award in 2010. He is a member of the Japan Society of Mechanical Engineers (JSME), the Japan Society for Precision Engineering (JSPE), the Japan Society of Tribologist (JAST) and the Japan Society for Grinding Engineering. He is also the current Chair of MicroNano Mechanical Science and Engineering Department, Graduate School of Engineering, and Adviser to the president of Nagoya University, Japan.

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