Controlling the Structural, Mechanical and Frictional Properties of MoSx Coatings by High-Power Impulse Magnetron Sputtering

Abstract

Tribology, as the science and technology of interacting surfaces, typically relies on liquid lubricants which reduce friction and wear. For environmentally friendly tribological purposes and applications requiring a liquid-free performance, solid lubricants, such as MoS2 coatings, play an essential role. It is crucial to understand the interplay between the parameters of the coating synthesis and the characteristics of the coating. The impact of the deposition parameters on the structural, mechanical and frictional properties of MoSx thin films, which are synthesized by high-power impulse magnetron sputtering, are studied. The morphology, topography and stoichiometry (2.02 < x < 2.22) of the films are controlled by, in particular, the bias-voltage and heating power applied during the sputtering process. In combination with a low pulse frequency the hardness and elastic stiffness of the MoSx films are enhanced up to 2 and 90 GPa, respectively. This enhancement is assigned to a shortening of the Mo-S bonding lengths and a strengthening in the interatomic coupling as well as to a formation of small-sized crystallites at the surface. The friction coefficient reduces to µ = 0.10 for films with an initial (100) orientation and the mean roughness of the MoSx films decreases below 15 nm by shortening the cathode pulses.

Influence of V doping on the microstructure, chemical stability, mechanical and tribological properties of MoS2 coatings

“…That is, the following growth pattern exists where the MoS 2 coating grows first into a dense coherent layer with (002) basal orientation and then into a loose columnar structure with (h k 0) edge orientation (Gao et al , 2017). Diffraction peaks are clearly observed for pure MoS 2 coatings at 2θ of about 11°, 33° and 59°, referring to (002), (100) and (110) crystal plane, respectively (Kokalj et al , 2020). However, the intensity value of the (002) peak increases and the peak becomes wider as the sputtering current of the V target increases.…”

Solid Lubrication System and Its Plasma Surface Engineering: A Review

“…The layers consist of S-Mo-S three-atomic-layer structures held together by weak van der Waals forces between the layers [194,[218][219][220]. In the occurrence of sliding, the crystalline layers of MoS2 will easily slide and orient parallel to the direction of relative movement, which provides the lubricating effect [209,[221][222][223]. On the other hand, the solid ionic bond between S and Mo provides the lamellae a high resistance to asperities penetration.…”

Effect of Argon Flow Rate on Tribological Properties of Rare Earth Ce Doped MoS2 Based Composite Coatings by Magnetron Sputtering

“…Therefore, improving the process is also essential to improving the performance of MoS 2 -based coatings. Kokalj et al [18] studied the structural changes of MoS x films under pulse frequency and other parameters. They found that low pulse frequency shortened the Mo-S bond length, which could significantly improve the hardness and elastic stiffness of the film.…”