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Article Dans Une Revue Tribology Online Année : 2023

Investigation of Solid Lubrication Processes of DLC Films with a Unique 6 Axes UHV Tribometer

Résumé

Among Diamond-Like Carbon (DLC) materials, hydrogenated amorphous carbon (a-C:H) coatings may exhibit super-low friction coefficients (< 0.01) under vacuum. A running-in phase is observed in the first few cycles of sliding before reaching a steady state of super-low friction. In this study, a unique ultra-high vacuum tribometer, with 4 different axes of motions and a 6 axes force sensor, is used to characterize the tribological behavior of a steel pin / a-C:H coated flat contact. An original crossing-tracks method is proposed to dissociate the respective roles of tribofilm build-up and surface modifications on the a-C:H in the achievement of superlow friction. A previously build-up tribofilm on the steel counterface shortens the running-in phase by 18 cycles and reduces the initial friction coefficient by 32%. Sliding on a previously rubbed area of the coating allows an additional initial friction reduction of 36%. Morphological and chemical investigations on the a-C:H coated flat using Atomic Force Microscopy and X-ray Photoelectron Spectroscopy reveal that the initial nanoasperities were smoothed, eventually leading to shallow matter transfers and tribofilm thickening on the counterface. Carbon-to-carbon bonds rupture and a reorganization in the carbon structure leads to an increase of the sp 2 /sp 3 hybridization ratio.
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hal-04192025 , version 1 (31-08-2023)

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Paternité - Pas d'utilisation commerciale - Pas de modification

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Antoine Normant, Jules Galipaud, Frédéric Dubreuil, Julien Fontaine. Investigation of Solid Lubrication Processes of DLC Films with a Unique 6 Axes UHV Tribometer. Tribology Online, 2023, 18 (5), pp.239-248. ⟨10.2474/trol.18.239⟩. ⟨hal-04192025⟩
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