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Novel multilayered films were engineered by integrating W 2 N and Ag-SiN x layers in a multilayer structure to obtain improved hardness and tribological properties. The films were fabricated by alternating magnetron sputtering, depositing 40 nm layers of W 2 N with varying thickness of Ag-SiN x layers varying in thickness from 4 to 20 nm. The effect of the increase thickness of the Ag-SiN x layers in the films microstructure and tribological properties were accessed. Tribological experiments were conducted at room temperature (RT), 500 °C, and RT-500 °C cycling conditions. The results revealed the production of a multilayered structure comprising single fcc-W 2 N layers interspersed with dual-phase layers consisting of fcc-Ag and amorphous SiN x phases. Tribological results indicated an improvement in the tribological performance with increase thickness of the Ag-SiN x layer up to 12 nm. The tribo-synergistic/combined action of both W 2 N and Ag-SiN x layers, along with the presence of layered lubricant tribo-phases of WO 3 and Ag 2 WO 4 , showcased the pivot role in reducing friction and enhancing wear resistance. The optimized multilayered film, featuring a 12 nm Ag-SiN x layer, demonstrated exceptional tribological properties under temperature-cycling from RT to 500 °C. [Display omitted] [ABSTRACT FROM AUTHOR]

The tribological processes still cause a significant increase in energy consumption worldwide. In this work, we deposited self-lubricating coatings for the purpose of reducing friction during sliding against rubber. One of the coatings was also treated with laser. We studied the morphological, structural and mechanical properties of the proposed solutions. Tribological tests were performed using a pin on disk device. The laser treatment improved the crystallinity of the WSx phase. This improvement was coupled with a reduction of the hardness in the laser-treated areas due to graphitization. The laser-treated sample showed a reduction in friction only during the initial stages of sliding. The lowest friction was observed during the testing of unalloyed sputtered WS x coating, but it suffered more wear. [Display omitted] [ABSTRACT FROM AUTHOR]

W–S–N self-lubricant coatings were deposited by d.c. reactive magnetron sputtering at two total discharge pressures of 0.6 and 1.2 Pa. The nitrogen content and S/W ratio varied from 0 to 30 at.%, and 0.6 to 1.6, respectively. The effect of deposition conditions on chemical composition, structure and mechanical properties was studied; coatings with the most promising properties have been selected for tribological testing. Coatings were nanostructured with nanograins of tungsten disulfide; the size of which decreased with increasing nitrogen content. Hardness increased with N content up to 7 GPa for coating deposited with a discharge pressure of 1.2 Pa; coatings deposited at lower pressure exhibited hardness around 9 GPa. Friction and wear behavior in humid air and dry nitrogen was evaluated using a pin-on-disk tribometer. The wear tracks and the ball wear scars were analyzed by Raman spectroscopy and scanning electron microscopy. Although the friction coefficient in dry nitrogen was significantly lower than in humid air, the wear rate was similar for both environments. Detailed wear track surface analysis showed that the tribolayer formed on the surface contained mostly tungsten disulfide and tungsten oxide. [ABSTRACT FROM AUTHOR]

Abstract: Transition metal dichalcogenides (TMD) are well known for their self lubricant properties, due to unique crystal structure, with low hardness which makes them inappropriate in applications requiring high load bearing capacity. Nevertheless, there is still a considerable potential for further improvements since other TMDs such as diselenides remain almost unknown. The WSeC coatings were deposited by either co-sputtering from WSe2 and C targets or by working in reactive mode in an Ar+CH4 atmosphere. Carbon content varied from 25at.% up to 70at.%, Se/W ratio of co-sputtered coatings was between 0.9 and 1.0, with no significant influence of the carbon content on their variations, while in the reactive process it reached values higher than 1.7. The hardness of the coatings was evaluated by nanoindentation, with values between 1.6 and 5.6GPa. The structure of the coatings was analysed by X-ray diffraction in glancing mode, showing that the coatings have a quasi-amorphous structure. Finally, the selected samples were tested on pin-on-disc showing low friction properties of WSeC co-sputtered coatings. [Copyright &y& Elsevier]

W–S–C thin films were deposited by magnetron sputtering in a semi-industrial deposition unit. Various parameters like the composition, crystallinity, morphology and hardness were studied. A single coating was selected for tribological studies in different testing environments. The tribological response during ambient air testing was governed mainly by carbon-based phase at low normal loads and both carbon-based and WS 2 rich tribofilms at higher loads. Very low coefficients of friction (~0.01) were obtained during testing at elevated temperature due to accelerated formation of WS 2 rich tribofilms. The tribological response in a vacuum against a steel-based counterbody was unsatisfactory due to the presence of a carbon-phase at the sliding interface. Discrepancies were observed between the tribological response in dry N 2 and vacuum environments. • Self-lubricant W–S–C coatings were deposited by magnetron sputtering in a semi-industrial unit. • The composition was affected by the target to substrate distance, the power applied to the targets and substrate bias. • Good tribological performance was observed during testing at RT and elevated temperatures up to 400 °C. • Coating both counterbodies can greatly improve the tribological performance in a vacuum environment. [ABSTRACT FROM AUTHOR]