Resonant Raman scattering characterization of thermally annealed HiPIMS deposited MoS  coatings

Moldenhauer, Henning; Wittig, Alexandra; Kokalj, David; Stangier, Dominic; Brümmer, Andreas; Tillmann, Wolfgang; Debus, J.

doi:10.1016/j.surfcoat.2019.124891

Cited by 10 publications

(6 citation statements)

References 43 publications

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“…Figure 3 shows the Raman spectrum of the as-deposited MoS x film measured at a laser power of 0.18 mW. The spectrum contains optical phonon modes and out-of-plane (ZA) and in-plane longitudinal (LA) acoustic phonon modes which are typical for MoS 2 [15][16][17][18]. Within the frame of the point group D 6h notation, the most prominent optical phonon modes of MoS 2 are the E 1g mode at about 287 cm −1 , which describes an in-plane displacement of S atoms, the in-plane E 2g 1 mode at 372 cm −1 and the out-of-plane A 1g mode of only S atoms at 405 cm −1 .…”

Section: Structural and Mechanical Properties Of The As-deposited Mosmentioning

confidence: 99%

Investigation of the Tribofilm Formation of HiPIMS Sputtered MoSx Thin Films in Different Environments by Raman Scattering

et al. 2019

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Understanding the generation of third body particles and their contribution to the formation of tribofilms of MoS x thin films is still challenging due to a large number of influencing factors. Besides the structure of the as-deposited MoS x films, the environment and the conditions during the Ball-on-disk tests affect tribofilms and thus the friction. Therefore, the influence of the surface pressure and sliding velocity in air, argon and nitrogen environments on the generation of the third body particles and the tribofilm formation of randomly oriented MoS x films is investigated. A high surface pressure is one major factor to achieve low friction, especially under humid conditions, which is important considering the use in industrial applications, for example dry-running screw machines. However, the mechanisms leading to that frictional behavior are still affected by the surrounding environment. While low friction is caused by a more extensive tribofilm formation in air, in argon and nitrogen, large size third body particles dispensed all over the contact area contribute to a lower friction. Raman scattering reveal a different chemistry of these particles reflected in the absence of laser-or temperature-induced surface oxidation compared to the as-deposited film and the wear track. The Raman scattering results are discussed with respect to the wear particle size, its chemical reactivity and strain-induced bonding changes.

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Section: Structural and Mechanical Properties Of The As-deposited Mosmentioning

confidence: 99%

Investigation of the Tribofilm Formation of HiPIMS Sputtered MoSx Thin Films in Different Environments by Raman Scattering

et al. 2019

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“…Most studies that have obtained Mo/W/S x /Se x coatings have done so with a chalcogen-to-metal ratio within~1 < x ≤ 2, and have tested these coatings for tribological properties. When the mentioned ratio declines, the coefficient of friction either decreases or grows as the composition of the coatings approaches stoichiometric values [23,24]. The nature of this dependence is affected to some degree by the structural state of the coatings (the texture).…”

Section: Introductionmentioning

confidence: 99%

Reactive Pulsed Laser Deposition of Clustered-Type MoSx (x ~ 2, 3, and 4) Films and Their Solid Lubricant Properties at Low Temperature

et al. 2020

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We studied the tribological properties of amorphous molybdenum sulfide (MoSx) thin-film coatings during sliding friction in an oxidizing environment at a low temperature (−100 °C). To obtain films with different sulfur contents (x ~ 2, 3, and 4), we used reactive pulsed laser deposition, where laser ablation of the Mo target was performed in H2S at various pressures. The lowest coefficient of friction (0.08) was observed during tribo-testing of the MoS3 coating. This coating had good ductility and low wear; the wear of a steel counterbody was minimal. The MoS2 coating had the best wear resistance, due to the tribo-film adhering well to the coating in the wear track. Tribo-modification of the MoS2 coating, however, caused a higher coefficient of friction (0.16) and the most intensive wear of the counterbody. The MoS4 coating had inferior tribological properties. This study explored the mechanisms of possible tribo-chemical changes and structural rearrangements in MoSx coatings upon contact with a counterbody when exposed to oxygen and water. The properties of the tribo-film and the efficiency of its transfer onto the coating and/or the counterbody largely depended on local atomic packing of the nanoclusters that formed the structure of the amorphous MoSx films.

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“…The linewidths of the optical phonon modes at about 390 cm −1 and the acoustic phonons at about 180 cm −1 are broad for all films studied. They are broader than the typically observed lines in MoS 2 layered structures or bulk crystals [36,54] and in HiPIMS MoS x films [36,54]. On the one hand, the broadening may be assigned to a non-uniform stoichiometric ratio of the Mo and S atoms.…”

Section: Structural Properties Of the Mos X Filmsmentioning

confidence: 68%

“…According to Aubert et al the minimum friction coefficient could be obtained for S/Mo ratios between 1.5 and 1.6 [18]. The low friction coefficient may be ascribed to the basal (002) orientation within the MoS x film [20,36].…”

Section: Mechanical and Tribological Propertiesmentioning

confidence: 96%

“…Thus, the tribological properties, like the wear resistance of the film grown by HiPIMS can be improved [34]. Up to now, mainly composite coatings were grown by the HiPIMS method, for example (Cr 1-x Al x )N+MoS y [35] and pure MoS x HiPIMS coatings [36,37] have only been rarely studied. For MoS x thin films grown in HiPIMS mode, an increase of the bias-voltage leads to a more pronounced (100) orientation accompanied by an decrease of the friction coefficient [37].…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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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.

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Resonant Raman scattering characterization of thermally annealed HiPIMS deposited MoS coatings

Cited by 10 publications

References 43 publications

Investigation of the Tribofilm Formation of HiPIMS Sputtered MoSx Thin Films in Different Environments by Raman Scattering

Investigation of the Tribofilm Formation of HiPIMS Sputtered MoSx Thin Films in Different Environments by Raman Scattering

Reactive Pulsed Laser Deposition of Clustered-Type MoSx (x ~ 2, 3, and 4) Films and Their Solid Lubricant Properties at Low Temperature

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

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