ACS Publications. Most Trusted. Most Cited. Most Read
My Activity
CONTENT TYPES

Figure 1Loading Img

Multiwall Carbon Nanotubes for Solid Lubrication of Highly Loaded Contacts

  • Timothy MacLucas*
    Timothy MacLucas
    Chair of Functional Materials, Saarland University, Campus D3.3, Saarbrücken66123, Germany
    *Email: [email protected]
  • Andreas Klemenz
    Andreas Klemenz
    Fraunhofer Institute for Mechanics of Materials IWM, MicroTribology Center μTC, Woehlerstr. 11, 79108Freiburg, Germany
  • Patrick Grünewald
    Patrick Grünewald
    INM─Leibniz Institute for New Materials, 66123Saarbrücken, Germany
  • Volker Presser
    Volker Presser
    INM─Leibniz Institute for New Materials, 66123Saarbrücken, Germany
    Department of Materials Science & Engineering, Saarland University, Campus D2.2, 66123Saarbrücken, Germany
    Saarene─Saarland Center for Energy Materials and Sustainability, 66123Saarbrücken, Germany
  • Leonhard Mayrhofer
    Leonhard Mayrhofer
    Fraunhofer Institute for Mechanics of Materials IWM, MicroTribology Center μTC, Woehlerstr. 11, 79108Freiburg, Germany
  • Gianpietro Moras
    Gianpietro Moras
    Fraunhofer Institute for Mechanics of Materials IWM, MicroTribology Center μTC, Woehlerstr. 11, 79108Freiburg, Germany
  • Sebastian Suarez
    Sebastian Suarez
    Chair of Functional Materials, Saarland University, Campus D3.3, Saarbrücken66123, Germany
    Department of Materials Science & Engineering, Saarland University, Campus D2.2, 66123Saarbrücken, Germany
  • Martin Dienwiebel
    Martin Dienwiebel
    Fraunhofer Institute for Mechanics of Materials IWM, MicroTribology Center μTC, Woehlerstr. 11, 79108Freiburg, Germany
    Karlsruhe Institute of Technology (KIT), IAM─Institute for Applied Materials, MicroTribology Center μTC, Straße am Forum 7, 76131Karlsruhe, Germany
  • Frank Mücklich
    Frank Mücklich
    Chair of Functional Materials, Saarland University, Campus D3.3, Saarbrücken66123, Germany
  • , and 
  • Michael Moseler*
    Michael Moseler
    Fraunhofer Institute for Mechanics of Materials IWM, MicroTribology Center μTC, Woehlerstr. 11, 79108Freiburg, Germany
    Modelling of Functional Nanomaterials Group, Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104Freiburg, Germany
    Freiburg Materials Research Center, University of Freiburg, Stefan-Meier-Str. 21, 79104Freiburg, Germany
    Cluster of Excellence livMatS, Freiburg Center for Interactive Materials and Bioinspired Technologies, University of Freiburg, Georges-Köhler-Allee 105, 79110Freiburg, Germany
    *Email: [email protected]
Cite this: ACS Appl. Nano Mater. 2023, 6, 3, 1755–1769
Publication Date (Web):January 26, 2023
https://doi.org/10.1021/acsanm.2c04729
Copyright © 2023 The Authors. Published by American Chemical Society

    Article Views

    418

    Altmetric

    -

    Citations

    -
    LEARN ABOUT THESE METRICS
    Read OnlinePDF (5 MB)
    Supporting Info (4)»

    Abstract

    Abstract Image

    When lubrication of rolling bearings with oil or grease is not possible, for example because the lubricant evaporates in vacuum, solid lubrication by multiwall carbon nanotubes (MWCNT) is a viable alternative. To understand the mechanisms underlying MWCNT lubrication of highly loaded contacts, we combine an experimental approach with large-scale molecular dynamics (MD) simulations. Tribometry is performed on ground iron plates coated with two different types of MWCNTs by electrophoretic deposition. Although structural differences in the MWCNT materials result in slightly different running-in behavior, most of the tests converge to a steady-state coefficient of friction of 0.18. The resulting wear tracks and tribolayers are subjected to structural and chemical characterization and suggest a tribo-induced phase transformation resulting in tribolayers that consist of MWCNT fragments, iron oxide, and iron carbide nanoparticles embedded in an amorphous carbon matrix. Covalent bonding of the tribolayer to the iron surface and low carbon transfer to the alumina counter body indicate sliding at the tribolayer/ball interface as the dominant mechanism underlying MWCNT solid lubrication. MD simulations of nascent a-C tribofilms lubricated by MWCNT bundles and stacks of crossed MWCNTs reveal two different sliding regimes: a low-load regime that leaves the MWCNTs intact and a high-load regime with partial collapse of the tube structure and formation of a-C regions. The critical load for this transition increases with the filling ratio of the MWCNT and the packing density of the stacks. The former determines the stability of the MWCNT, while the latter controls the local stresses at the MWCNT crossings. For both MWCNT materials, the high-load regime is predicted for the experimental loads. This is confirmed by a remarkable agreement between transmission electron microscopy (TEM) and atomistic simulation images. Based on the findings of this work, a multistep lubrication mechanism is formulated for MWCNT coatings rubbing against alumina on an iron substrate.

    Supporting Information

    ARTICLE SECTIONS
    Jump To

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsanm.2c04729.

    • Additional MD simulation results for (10,10) and (40,40) MWCNT (Figures S1 and S2); relationship between transition pressure and filling ratio for (10,10), (20,20), and (40,40) MWCNTs (Figure S3); near-surface cross-sectional transmission electron micrographs of the GS-derived tribofilm/substrate (Figure S4); additional transmission electron micrographs of the samples shown in Figure 4 (Figures S5–S9); role of coating thickness for tribological evaluation (S10); and lubricant retention (S11) (PDF)

    • Video of MD simulation shown in Figure 5c (Movie_12c) (MP4)

    • Video of MD simulation shown in Figure 5d (Movie_12d) (MP4)

    • Video of MD simulation shown in Figure 5e (Movie_12e) (MP4)

    Terms & Conditions

    Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

    Cited By

    This article has not yet been cited by other publications.

    Pair your accounts.

    Export articles to Mendeley

    Get article recommendations from ACS based on references in your Mendeley library.

    Pair your accounts.

    Export articles to Mendeley

    Get article recommendations from ACS based on references in your Mendeley library.

    You’ve supercharged your research process with ACS and Mendeley!

    STEP 1:
    Click to create an ACS ID

    Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

    Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

    Please note: If you switch to a different device, you may be asked to login again with only your ACS ID.

    MENDELEY PAIRING EXPIRED
    Your Mendeley pairing has expired. Please reconnect