Femtosecond-laser surface modification and micropatterning of diamond-like nanocomposite films to control friction on the micro and macroscale
Laser surface micropatterning (texturing) of hard materials and coatings is an effective technique to improve tribological systems. In the paper, we have investigated the laser-induced surface modifications and micropatterning of diamond-like nanocomposite (DLN) films (a-C:H,Si:O) using IR and visib...
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Veröffentlicht in: | Journal of applied physics 2017-10, Vol.122 (14) |
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Sprache: | eng |
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Zusammenfassung: | Laser surface micropatterning (texturing) of hard materials and coatings is an effective
technique to improve tribological systems. In the paper, we have investigated the
laser-induced surface modifications and micropatterning of diamond-like nanocomposite
(DLN) films (a-C:H,Si:O) using IR and visible femtosecond (fs) lasers, focusing on the
improvement of frictional properties of laser-patterned films on the micro and macroscale.
The IR and visible fs-lasers, operating at λ = 1030 nm and λ = 515 nm wavelengths (pulse
duration 320 fs and pulse repetition rate 101 kHz), are used to fabricate different
patterns for subsequent friction tests. The IR fs-laser is applied to produce hill-like
micropatterns under conditions of surface graphitization and incipient ablation, and the
visible fs-laser is used for making microgroove patterns in DLN films under ablation
conditions. Regimes of irradiation with low-energy IR laser pulses are chosen to produce
graphitized micropatterns. For these regimes, results of numerical calculations of the
temperature and graphitized layer growth are presented to show good correlation with
surface relief modifications, and the features of fs-laser graphitization are discussed
based on Raman spectroscopy analysis. Using lateral force microscopy, the role of surface
modifications (graphitization, nanostructuring) in the improved microfriction properties
is investigated. New data of the influence of capillary forces on friction forces, which
strongly changes the microscale friction behaviour, are presented for a wide range of
loads (from nN to μN) applied to Si tips. In macroscopic ball-on-disk
tests, a pair-dependent friction behaviour of laser-patterned films is observed. The first
experimental data of the improved friction properties of laser-micropatterned DLN films
under boundary lubricated sliding conditions are presented. The obtained results show the
DLN films as an interesting coating material suitable for laser patterning applications in
tribology. |
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ISSN: | 0021-8979 1089-7550 |
DOI: | 10.1063/1.4998586 |