Lubricating Properties of Cyano-Based Ionic Liquids against Tetrahedral Amorphous Carbon Film

Coatings

Ryo Tsuboi¹  Chiharu Tadokoro²  Masaaki Miyatake³  Shinya Sasaki³  Hikaru Okubo³  Shouhei Kawada³  Seiya Watanabe³ 

[1] Department of Mechanical Engineering, Daido University, 10-3 Takiharu-cho, Minami-ku, Nagoya-shi, Aichi 457-8530, Japan;Department of Mechanical Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama-shi, Saitama 338-8570, Japan;Department of Mechanical Engineering, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan;

关键词: friction reduction;    ionic liquid;    lubrication;    surface chemistry;    tetrahedral amorphous carbon;   

DOI  :  10.3390/coatings10020153

来源: DOAJ

【 摘 要 】

Ionic liquids have unique characteristics, which render them ideal candidates as new base oils or additives. In particular, there are great expectations from the combination of diamond-like carbon and cyano-based ionic liquids. Lubricating properties of cyano-based ionic liquids have been studied on specific tetrahedral amorphous carbon (ta-C) films. After lubrication, ta-C film/ta-C film contact interface exhibits exceedingly low friction. Therefore, it is necessary to understand this low friction phenomenon. The current study evaluated the lubricating mechanism of cyano-based ionic liquids against ta-C films. 1-Butyl-3-methylimidazolium dicyanamide ((BMIM)(DCN)) and 1-butyl-3-methylimidazolium tricyanomethane ((BMIM)(TCC)) were used as lubricants, with the latter exhibiting low friction coefficient of 0.03. Steel cylinders and disks with ta-C films were used as test specimens. Raman spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and thermogravimetric analysis (TGA) helped us understand the mechanism of low friction induced by (BMIM)(TCC). Graphitization of the ta-C film at high temperatures might have caused the reduction in friction between the films. Similarly, anion adsorption on the worn surface at high temperatures also led to reduced friction. However, the TGA result showed a different trend than that of the sliding test. Our results indicate that the cyano-based ionic liquids underwent tribo-decomposition at low temperatures. Further, a minimum temperature was required for the adsorption of anions onto the sliding surface.

【 授权许可】

Unknown