Ultra-Low Friction on Tetrahedral Amorphous Diamond-Like Carbon (ta-C) Lubricated with Ethylene Glycol

Bachmann, Svenja and Schulze, Marcus and Krell, Lisa and Merz, Rolf and Wahl, Michael and Stark, Robert :
Ultra-Low Friction on Tetrahedral Amorphous Diamond-Like Carbon (ta-C) Lubricated with Ethylene Glycol.
[Online-Edition: https://doi.org/10.3390/lubricants6030059]
In: Lubricants, 6 (3) ISSN 2075-4442
[Article] , (2018)

Official URL: https://doi.org/10.3390/lubricants6030059

Abstract

Lubricated tetrahedral amorphous carbon coatings can show a very complex tribological behavior. In particular, friction regimes with extremely low friction have been observed. In tribological experiments with a ta-C/steel friction pair that was lubricated with ethylene glycol, we observed a sudden and very strong decrease in the effective friction coefficient from 0.45 to 0.01 after running-in. By varying different components of the tribological system after this abrupt decrease we investigated the role of the counter-body, the lubricant and the coating. To investigate the surface chemistry, static time-of-flight secondary ion mass spectrometry (ToF-SIMS), dynamic secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS) measurements were performed. Using deuterated lubricants, ToF-SIMS measurements allowed us to distinguish adsorption of hydrogen and hydroxyl-groups from the lubricant from the adsorption from the environment. Deuterated hydroxyl-groups from the lubricant adsorbed to the surface during the experiment. In particular, more adsorbed deuterated hydroxyl-groups were detected prior to the sudden decrease in the friction coefficient. Thus, the sudden decrease in the coefficient of friction was most likely caused by an interplay between the lubricant, the ta-C coating and the counter-body which lead to the formation of transfer and adsorption layers.

Item Type:	Article
Erschienen:	2018
Creators:	Bachmann, Svenja and Schulze, Marcus and Krell, Lisa and Merz, Rolf and Wahl, Michael and Stark, Robert
Title:	Ultra-Low Friction on Tetrahedral Amorphous Diamond-Like Carbon (ta-C) Lubricated with Ethylene Glycol
Language:	English
Abstract:	Lubricated tetrahedral amorphous carbon coatings can show a very complex tribological behavior. In particular, friction regimes with extremely low friction have been observed. In tribological experiments with a ta-C/steel friction pair that was lubricated with ethylene glycol, we observed a sudden and very strong decrease in the effective friction coefficient from 0.45 to 0.01 after running-in. By varying different components of the tribological system after this abrupt decrease we investigated the role of the counter-body, the lubricant and the coating. To investigate the surface chemistry, static time-of-flight secondary ion mass spectrometry (ToF-SIMS), dynamic secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS) measurements were performed. Using deuterated lubricants, ToF-SIMS measurements allowed us to distinguish adsorption of hydrogen and hydroxyl-groups from the lubricant from the adsorption from the environment. Deuterated hydroxyl-groups from the lubricant adsorbed to the surface during the experiment. In particular, more adsorbed deuterated hydroxyl-groups were detected prior to the sudden decrease in the friction coefficient. Thus, the sudden decrease in the coefficient of friction was most likely caused by an interplay between the lubricant, the ta-C coating and the counter-body which lead to the formation of transfer and adsorption layers.
Journal or Publication Title:	Lubricants
Volume:	6
Number:	3
Uncontrolled Keywords:	diamond-like carbon, ToF-SIMS, XPS, coefficient of friction, ethane-1,2-diol, ta-C
Divisions:	11 Department of Materials and Earth Sciences 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences > Material Science > Physics of Surfaces Exzellenzinitiative Exzellenzinitiative > Clusters of Excellence Exzellenzinitiative > Clusters of Excellence > Center of Smart Interfaces (CSI)
Date Deposited:	05 Aug 2018 19:56
DOI:	10.3390/lubricants6030059
Official URL:	https://doi.org/10.3390/lubricants6030059
URN:	urn:nbn:de:tuda-tuprints-76557
Funders:	We acknowledge support by the German Research Foundation and the Open Access Publishing Fund of Technische Universität Darmstadt.
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