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Micromachines 2017, 8(7), 217;

Effects of Environmental Gas and Trace Water on the Friction of DLC Sliding with Metals

Department of Hydrogen Energy Systems, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395, Japan
Department of Mechanical Engineering, Kyushu University, Fukuoka 819-0395, Japan
Research Center for Hydrogen Industrial Use and Storage, Kyushu University, Fukuoka 819-0395, Japan
International Institute for Carbon-Neutral Energy Research, Kyushu University, Fukuoka 819-0395, Japan
This paper is an extended version of our paper published in the 2016 International Conference on Engineering Tribology and Applied Technology (ICETAT 2016), Taipei, Taiwan, 4–6 November 2016.
Author to whom correspondence should be addressed.
Received: 23 June 2017 / Accepted: 8 July 2017 / Published: 11 July 2017
(This article belongs to the Special Issue Microtribology, Adhesion and Surface Engineering)
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This paper describes an experimental study on the friction of a-C:H diamond-like carbon (DLC) and ta-C DLC coatings in gas with different concentration of trace water. Pin-on-disk sliding experiments were conducted with DLC coated disks and aluminum pins in hydrogen, nitrogen, and argon. Trace oxygen was eliminated to less than 0.1 ppm, while water in the gas was controlled between 0 and 160 ppm. Fourier transform infrared spectroscopy (FT-IR) and laser Raman spectroscopy were used to analyze the transfer films on the metal surfaces. It was found that trace water slightly increased friction in hydrogen gas, whereas trace water caused a significant decrease in the friction coefficient in nitrogen and argon, particularly with a-C:H DLC. The low friction in hydrogen was brought about by the formation of transfer films with structured amorphous carbon, but no differences in the structure and contents of the films were found in the tests with and without trace water. In nitrogen and argon, the low friction with a-C:H DLC was achieved by the gradual formation of transfer films containing structured amorphous carbon, and FT-IR spectra showed that the films contained CH, OH, C–O–C, and C–OH bonds. View Full-Text
Keywords: DLC; friction; gas; trace water; aluminum; FT-IR; laser Raman spectroscopy DLC; friction; gas; trace water; aluminum; FT-IR; laser Raman spectroscopy

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Kurahashi, Y.; Tanaka, H.; Terayama, M.; Sugimura, J. Effects of Environmental Gas and Trace Water on the Friction of DLC Sliding with Metals. Micromachines 2017, 8, 217.

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