Tribochemical induced wear and ultra-low friction of superhard ta-C coatings

Makowski, Stefan; Schaller, F.W.; Weihnacht, Volker; Englberger, Gregor; Becker, Michael F.

doi:10.1016/j.wear.2017.08.015

Cited by 27 publications

(11 citation statements)

References 52 publications

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“…In addition, with the rapeseed oil lubrication that exhibited low friction coefficients, wear marks with more distinct sliding marks over a wider area were observed compared with the sliding surface lubricated with linseed oil. The results suggest that ultra-low friction attributable to tribochemical reactions occurred on the ta-C coating under oleic acid lubrication, which is similar to the phenomenon reported by Dr.Stefan Makowski in Scientific Reports, Physical Review [8].…”

Section: Appearance and Surface Roughness Of Friction Surfacesupporting

confidence: 85%

Effect of Degree of Unsaturation in Vegetable Oils on Friction Properties of DLC Coatings

2021

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Recently, it has been reported that combinations of various types of vegetable oils containing organic acids and DLC coatings are effective for reducing friction, but there are few reports of detailed investigations into the relationship between differences in the chemical structures of vegetable oil lubricants and friction reduction. Therefore, the authors investigated the influence on friction properties of two types of DLC coatings, a-C:H and ta-C under lubrication with vegetable oils which have different degrees of unsaturation. The ta-C coating displayed markedly lower friction coefficients than the a-C:H coating and the uncoated steel with all of the vegetable oil lubricants used. It was found that the low friction properties of the ta-C coating showed even lower friction coefficients with vegetable oils containing a higher content of monounsaturated fatty acids. Additionally, the sliding surfaces of ta-C coated discs and cylinders were analyzed by XPS and ToF-SIMS analysis. The results confirmed the formation of a surface layer consisting of C-OH bonds, and a lower friction coefficient was seen as the detected intensity of these bonds increased.

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Section: Appearance and Surface Roughness Of Friction Surfacesupporting

confidence: 85%

Effect of Degree of Unsaturation in Vegetable Oils on Friction Properties of DLC Coatings

2021

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“…The authors have ruled out a "selfassembled monolayer" mechanism and are instead proposing what they call "H-bond network" model [24]. This model has been used to explain the low friction achieved with glycerol and tetrahedral amorphous carbon (ta-C) DLC coatings in pure sliding boundary lubrication with even lower friction as a result compared to a-C:H-coated specimens [22][23][24][25][26] Whether this mechanism is responsible for the friction reduction in the present investigation is not known, follow-up analysis involving time-of-flight secondary ion mass spectroscopy (ToF-SIMS) needs to be performed. It is however reasonable to believe that part of the low boundary friction obtained in the present a-C:H-glycerol case is related to the formation of a glycerol-based tribofilm.…”

Section: Resultsmentioning

confidence: 99%

“…A few studies have been conducted using both glycerol and DLC-coated surfaces to achieve even lower friction in pure sliding boundary-lubricated contacts [22][23][24][25][26]. In some of these studies, friction coefficients below 0.01 is found.…”

Section: Introductionmentioning

confidence: 99%

DLC and Glycerol: Superlubricity in Rolling/Sliding Elastohydrodynamic Lubrication

Björling

Shi

2019

Tribol Lett

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Low friction is one of the most important parameters for the development of machine components and machines with high efficiency. Many of the common machine components of today such as gears, rolling element bearings and cam-followers are defined by their non-conformal contacts leading to high-contact pressures, typically 1-4 GPa. The lubrication of such contacts is usually called elastohydrodynamic lubrication (EHL). Diamond-like carbon (DLC) coatings and glycerol have individually been shown to produce low friction in boundary, mixed and full film lubrication. A few studies have been conducted using both glycerol and DLC-coated surfaces to achieve even lower friction in pure sliding boundary-lubricated contacts. However, the literature is lacking studies of how the combination of glycerol and DLC performs in non-conformal rolling/sliding contacts where many common machine components operate. Such a study is presented in this article where a ball-on-disc test rig is used to investigate the performance of the combination of DLC and glycerol at pressures up to 1.95 GPa at various entrainment speeds and slide-to-roll ratios. The investigation shows that the DLC-glycerol combination provides very low friction values, in some cases, below the superlubricity threshold of 0.01, possibly shown for the first time at such high pressure in a non-conformal rolling/sliding contact. The low friction mechanism in full film lubrication is a combination of the low pressure-viscosity and high temperature-viscosity sensitivity of glycerol in combination with thermal insulation of the DLC coating and is presented as thermally assisted liquid superlubricity.

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“…Advanced simulations [158] have shown increasing C-C bond formation during sliding. This area has received increasing attention in the past few years and is being actively explored with different hydrocarbons, catalysts [159], environmental conditions and applications like self-lubrication in automotive [129], mechanical components [161], microelectromechanical systems [162], and medical products [163]. The idea has further advanced to treat pre-deposited DLC coatings with carbon enriched lubricants to gain superior lubricity by yielding graphene [164,165] or other by-products [166] through tribo-chemical interaction.…”

Section: Microstructure Of Dlc Coatings Produced With Non-conventiona...mentioning

confidence: 99%

Deposition of diamond-like carbon coatings: Conventional to non-conventional approaches for emerging markets

Zia

Birkett

2021

Ceramics International

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Tribochemical induced wear and ultra-low friction of superhard ta-C coatings

Cited by 27 publications

References 52 publications

Effect of Degree of Unsaturation in Vegetable Oils on Friction Properties of DLC Coatings

Effect of Degree of Unsaturation in Vegetable Oils on Friction Properties of DLC Coatings

DLC and Glycerol: Superlubricity in Rolling/Sliding Elastohydrodynamic Lubrication

Deposition of diamond-like carbon coatings: Conventional to non-conventional approaches for emerging markets

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