Search

To obtain Mo–S–C thin-film coatings on steel substrates with varying structural and chemical states, pulsed laser codeposition method was used at room temperature, including the first ever use of reactive codeposition of Mo and C in H2S. The conditions are determined for obtaining sufficiently smooth layers with optimal local packing of atoms in amorphous MoSx and diamond-like carbon nanophases, which yielded relatively high wear resistance and a low sliding friction coefficient (~0.1) in air without a long running-in phase.

The effect of the nanostructure and chemical composition of thin Mo–Se–C films on the run-in of the diamond-like carbon coating (a-C) and the steel counterbody during ball-on-disk sliding test is studied. At the final stage of the deposition of the a-C coating on the steel substrate, a flow of atoms from the MoSe2 target was added to the flow of atoms being deposited. The influence of the air humidity on the selection of optimum structure and chemical composition of the film, which provide a fairly low (

Nanocomposite thin C-Ti-WSe x coatings, which contain antifriction (WSe x and amorphous carbon a-C) and hard (β-WC and TiC) components, are produced by pulsed laser deposition. In order to improve the tribological characteristics of the WSe x phase and to transform the structural state of the a-C matrix, alloying with titanium is used. The characteristics of the coatings are determined using the sliding of a steel ball at an increased humidity. A comparison of the characteristics of a composite C-Ti-WSe x coating and a carbon coating alloyed with titanium (a-C(Ti)) shows that the modification of the a-C matrix by introducing the WSe x phase leads to an increase in the coefficient of friction from 0.05 to 0.2; the wear of the composite coating is approximately six times higher than that of the a-C(Ti) coating. Possible solutions for improving the tribological characteristics of the composite C-Ti-WSe x coating in humid air are considered.

Thin film, solid lubricating WSex coatings were deposited at room temperature on a steel substrate with a titanium underlayer by pulsed laser deposition (PLD). Two modes of PLD were investigated, i.e., the PLD under vacuum conditions and the PLD in a buffer gas (helium) at a pressure of 2–10 Pa. Gas was used to slow down the laser-induced atomic flux and to modify thus the conditions of the coatings growth. At a pressure ∼8 Pa, gas reduced the effectiveness of Se preferential sputtering by atomic flux, which resulted in the formation of coatings with a stoichiometric composition (x ≈ 2). The structure of the coatings was characterized by a greater degree of the perfect organization of atoms in the nanophase laminar packaging and reduced internal stresses. Studies by the ball-on-disk tests in humid air showed that the modification of the structure and the chemical composition of the coatings had a significant effect on their tribological behavior. Vacuum-deposited coatings fractured relatively quickly due to the cracking and delamination from the substrate surface along the sliding track. When the coatings deposited in helium were tested, wear by layer-by-layer removal was dominant, so the adhesive fracture was only observed in the local parts of the track. The simulation of the laser vapor deposition in the vacuum and in the buffer gas was performed. Likely factors that improve the tribological properties of the coating during deposition in the buffer gas were disclosed.