Tribology Letters

, Volume 39, Issue 1, pp 49–61

Atomistic Insights into the Running-in, Lubrication, and Failure of Hydrogenated Diamond-Like Carbon Coatings

Original Paper


The tribological performance of hydrogenated diamond-like carbon (DLC) coatings is studied by molecular dynamics simulations employing a screened reactive bond-order potential that has been adjusted to reliably describe bond-breaking under shear. Two types of DLC films are grown by CH2 deposition on an amorphous substrate with 45 and 60 eV impact energy resulting in 45 and 30% H content as well as 50 and 30% sp3 hybridization of the final films, respectively. By combining two equivalent realizations for both impact energies, a hydrogen-depleted and a hydrogen-rich tribo-contact is formed and studied for a realistic sliding speed of 20 m s−1 and loads of 1 and 5 GPa. While the hydrogen-rich system shows a pronounced drop of the friction coefficient for both loads, the hydrogen-depleted system exhibits such kind of running-in for 1 GPa, only. Chemical passivation of the DLC/DLC interface explains this running-in behavior. Fluctuations in the friction coefficient occurring at the higher load can be traced back to a cold welding of the DLC/DLC tribo-surfaces, leading to the formation of a transfer film (transferred from one DLC partner to the other) and the establishment of a new tribo-interface with a low friction coefficient. The presence of a hexadecane lubricant leads to low friction coefficients without any running-in for low loads. At 10 GPa load, the lubricant starts to degenerate resulting in enhanced friction.


Running-in Coatings Friction-reducing Boundary lubrication Friction mechanisms Unlubricated friction Carbon 

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Lars Pastewka
    • 1
    • 2
  • Stefan Moser
    • 1
  • Michael Moseler
    • 1
    • 2
    • 3
  1. 1.Fraunhofer-Institut für Werkstoffmechanik IWMFreiburgGermany
  2. 2.Physikalisches InstitutUniversität FreiburgFreiburgGermany
  3. 3.Freiburger MaterialforschungszentrumFreiburgGermany

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