Special Issue "Applied Nanotribology"

A special issue of Lubricants (ISSN 2075-4442).

Deadline for manuscript submissions: closed (31 March 2018).

Special Issue Editor

Prof. Dr. Matthias Scherge
Website
Guest Editor
Fraunhofer IWM MikroTribologie Centrum, Wöhlerstr. 11, 79108 Freiburg, Germany
Interests: materials; lubricants; coatings

Special Issue Information

Dear Colleagues,

The protection of our environment and sustainability issues are buzzwords a modern tribologist cannot ignore. Environmental protection comprises for example low- or no-emission vehicles and minimized oil consumption. Sustainability demands for long-living mechanical devices with high stability and low sensitivity to external disturbances.

To achieve these goals tribologists may use different levers. First of all, running-in procedures are very well suited to swiftly move a new tribological system into a state of low friction and low wear. Secondly oil and additive formulations are crucial not only during the running-in but also for the long-term performance of the tribosystems. Last, but not least, by means of optimized finishing procedures, the materials can be conditioned to withstand increasingly tougher boundary conditions with respect to load, speed, temperature and harsh environments.

This Special Issue of Lubricants intends to highlight nanoscale tribology activities apart from conventional approaches using probe methods such as atomic force or lateral force microscopy. "Applied Nanotribology" will focus on systems with ultra-low wear rates, their experimental observation, modelling and simulation. In addition, contributions on accompanying analytical methods that help to understand tribochemical reactions in the near-surface of the friction bodies are welcome.

Prof. Dr. Matthias Scherge
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Lubricants is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • ultra-low wear rates
  • tribochemistry
  • continuous friction and wear testing
  • surface science analytics
  • modelling and simulation
  • design of lubricants and additives
  • optimization of running-in
  • optimization of surface finishing procedures

Published Papers (4 papers)

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Research

Open AccessArticle
Tribology of Wire Arc Spray Coatings under the Influence of Regenerative Fuels
Lubricants 2018, 6(3), 60; https://doi.org/10.3390/lubricants6030060 - 09 Jul 2018
Cited by 1
Abstract
In order to further optimize the efficiency of today’s internal combustion engines, specific coatings are used on functional surfaces to reduce internal engine friction and wear. In the current research project, oxymethylene ether (OME) is discussed because it is CO2 neutral and [...] Read more.
In order to further optimize the efficiency of today’s internal combustion engines, specific coatings are used on functional surfaces to reduce internal engine friction and wear. In the current research project, oxymethylene ether (OME) is discussed because it is CO2 neutral and has a strong soot-reducing effect as a fuel or fuel additive. In some operational regimes of the internal combustion engine a dilution of engine oil by fuel must be assumed. In this paper, the frictional contact between piston ring and cylinder raceway is modelled using a pin-on-disk tribometer and the friction and wear behavior between a diamond-like carbon coating (DLC) and a thermal spray coating is characterized. The wear of the spray layer could be continuously detected by radionuclide technology (RNT). With the aid of photoelectron spectroscopic measurements (XPS), the steel thermal spray coating was chemically analyzed before and after the tribometer tests and the oxidative influence of OME was investigated. In addition, confocal microscopy was used to assess the topographies of the specimens. The measurements showed that the addition of OME to the lubricant reduced the viscosity and load-bearing capacity of the lubricating film, which led to an increase in the coefficient of friction. While almost no wear on the pin could be detected at 10% OME, the first visible material removal occurs at an OME content of 20% and the layer delaminated at 30% OME. The evaluation of the RNT wear tests showed that both the tests with engine oil and with engine oil plus 20% OME achieved very low wear rates. No corrosion of the thermal spray coating could be detected by XPS. Only the proportion of engine oil additives in the friction track increased with increasing OME concentration. Full article
(This article belongs to the Special Issue Applied Nanotribology)
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Open AccessArticle
Ultra-Low Friction on Tetrahedral Amorphous Diamond-Like Carbon (ta-C) Lubricated with Ethylene Glycol
Lubricants 2018, 6(3), 59; https://doi.org/10.3390/lubricants6030059 - 07 Jul 2018
Cited by 2
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Applied Nanotribology)
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Open AccessArticle
The Running-in of Lubricated Metal-Metal Contacts—A Review on Ultra-Low Wear Systems
Lubricants 2018, 6(2), 54; https://doi.org/10.3390/lubricants6020054 - 08 Jun 2018
Cited by 3
Abstract
The running-in of lubricated metal–metal contacts leading to ultra-low wear is inseparably connected with the formation of the third body and vice versa. Adequate tribological stressing provides the system with a power density that leads to complex changes of topography, near-surface morphology and [...] Read more.
The running-in of lubricated metal–metal contacts leading to ultra-low wear is inseparably connected with the formation of the third body and vice versa. Adequate tribological stressing provides the system with a power density that leads to complex changes of topography, near-surface morphology and chemical composition. During the running-in these changes proceed until the system shows small friction and ultra-low wear rates and performs stable with low sensitivity to external perturbations. By means of high-resolution wear measurement as well as physical and chemical analysis the capability of a tribological system to develop the third body can be determined. Moreover, the running-in can be controlled by sample finishing, oil additivation and the sequence of initial stressing steps. This contribution summarizes 20 years of own research on ultra-low wear systems and its applications. Full article
(This article belongs to the Special Issue Applied Nanotribology)
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Open AccessArticle
Pathways of Dissipation of Frictional Energy under Boundary Lubricated Sliding Wear of Martensitic Materials
Lubricants 2018, 6(2), 34; https://doi.org/10.3390/lubricants6020034 - 11 Apr 2018
Cited by 2
Abstract
The challenges of technical systems subjected to friction and wear become more demanding with steadily increasing stresses. Besides safety matters, failure of tribologically loaded systems can cause tremendous maintenance costs. Because of the lack of a general wear prediction model, tribometer tests must [...] Read more.
The challenges of technical systems subjected to friction and wear become more demanding with steadily increasing stresses. Besides safety matters, failure of tribologically loaded systems can cause tremendous maintenance costs. Because of the lack of a general wear prediction model, tribometer tests must be used in order to investigate wear behaviour of materials in certain tribological systems. Any well-aimed optimizations of tribological contacts requires a comprehensive understanding of friction and wear mechanisms. Otherwise the transferability into technical applications is questionable because of the wide range of applied loads, lubrication conditions, and materials microstructures. In this study, specimens with different topographies and subsurface microstructures were investigated prior to and after tribological testing. The analyses of surface and subsurface characteristics were performed by means of complementary high-resolution electron-microscopy techniques. The study attempted to link the findings to the wear behavior in order to gain information about the pathways of dissipation and transformation of frictional energy into wear. It was found that the dissipation pathways of base body and counter body were different, resulting in diverse tribological behaviour. Nonetheless, the presence of a near-surface grain-refined layers (tribomaterial) supported by a sub-surface strain gradient appears to provide a beneficial influence. Despite the fact that any direct or even conclusive relation to the topographies or subsurface microstructures cannot be given, the discussion provides some hints on how to analyse such systems for their characteristic mechanisms. In addition to the capability of such approach as one step of understanding, its limitations are shown and briefly discussed as well. Full article
(This article belongs to the Special Issue Applied Nanotribology)
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