Speech by: Prof. Dr. Hatsuhiko Usami
Surface Modification Process Based on Combined Mechanical Means
The present study describes the surface modification process and its applicability to improve
tribological performance of sliding interface of engine components such as a piston skirt
and a journal bearing. The proposed process consists of a interrupted micro cutting, a
micro shot peening and a roller burnishing. The modified surface composed of solid
lubricant such as graphite and sulfides mixed with soft interlayer such as metal or polymer
and the textured component surface. The coating process was carried out using a micro
shot peening and a roller burnishing process. The texture geometry was determined by the
interrupted micro cutting process.
Fundamental tribological properties was evaluated with a ball-on-disc and a ring-on–disc
type testing apparatuses to optimize the surface characteristics. The material of the mating
specimen was chromium alloy steel as the ball and cast iron for the ring. The surface
modification process was applied to the aluminum cast alloy disc. Results showed that friction
confidence of the modified surface was low and stable in a wide range of sliding conditions and
that the critical load due to seizure increased. In particular, a significant decrease in the
friction coefficient was found in a boundary lubrication regime. It was found that the
optimization of the interlayer such as the element and the volume fraction was an effective
means to increase the life of the modified layer.
The treatment was applied to the piston skirt surface with selected conditions from the
results of the fundamental tribological properties, then the friction performance was
evaluated with an actual engine system in a firing condition. The relation of tribological
properties between the fundamental and firing conditions was discussed.
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Personal Details
Prof. Dr. Hatsuhiko Usami is a professor of the Materials Science and Engineering department of Meijo University.
He received his bachelor’s from Meijo University and master’s and doctorate degrees in Mechanical Engineering from Nagoya Institute of Technology.
After graduating from graduate school, He worked for the Research Institute of material science, Japan Fine Ceramics Center (JFCC) as a researcher and studied crack extension and creep deformation mechanisms of engineering ceramics.
From 1995, He moved to the Mechanical Engineering Department of Meijo University and belonged to JFCC as a visiting researcher (1995-2005). From 2003 to 2007, he joined to tribology research group of the Advance Institute of Science and Technology (AIST) as a visiting researcher.
He contributed as a committee member of Japanese Industrial Standards (JIS) for internal friction (1995-1999) and high-temperature wear tests for ceramics (1998-2001).
He got a poster presentation award from the American Ceramics Society (1998) and a best presentation award from the committee of International Conference of Machine Design and Tribology (ICMDT, held in Jeju Island, 2009).
He is a member of the Japanese Society of Mechanical Engineers (JSME) and Japanese Society of Tribologists (JAST) and the Japanese Society of Precision Engineering (JSPE).
He contributed as a chief editor of the Journal of Advanced Mechanical Design, Systems, and Manufacturing (JAMDSM, 2015) for JSME and an executive member of JAST (2011-2012).