Tribological properties of hard a-C:H:F coatings

• Published in: Surface & coatings technology 2013-12, Vol.237, p.328-332
• Main Authors: Jaoul, C., Dublanche-Tixier, C., Jarry, O., Tristant, P., Lavoute, J.P., Kilman, L., Colas, M., Laborde, E., Ageorges, H.
• Format: Article
• Language: English
• Subjects: a-C:H:F; Applied sciences; Carbon; Coatings; Contact of materials. Friction. Wear; Cross-disciplinary physics: materials science; rheology; DLC; Exact sciences and technology; Fluorine; Friction; Hardness; Hydrogen storage; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Physics; Production techniques; Raman; Surface treatment; Surface treatments; Thin films; Tribology; Wear
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2013.07.042

Hydrogenated amorphous carbon thin films containing fluorine (a-C:H:F) have been produced by radio-frequency plasma enhanced chemical vapor deposition by using different F/H ratios in the gas phase. The introduction of fluorine from 0 to 19at.% resulted in a decrease of hydrogen content and to the formation of CF and CF2 bonds. For all the films, Raman analysis showed a typical diamond-like carbon response with an evolution of the structure to larger sp2 clusters with less hydrogen while fluorine content increased. The drop in hardness generally observed in the literature with fluorine introduction was less abrupt here: for a fluorine content up to 6.5at.%, the measured hardness was 28GPa, and for 19at.% of fluorine, value was 20GPa. These are quite high values for a-C:H:F thin films. Moreover, fluorine improved tribological behavior in dry conditions with friction coefficient slightly reduced at low fluorine content and wear rate significantly reduced: divided by two to four than the fluorine free reference coating. •a-C:H:F thin films with high hardness level (>20GPa)•Structure and bonding modification characterized for different F content•Slight reduction of hardness with F introduction•Small amount of F significantly improved wear rate and friction coefficient.