Structure, morphology and chemical composition of sputter deposited nanostructured Cr–WS2 solid lubricant coatings

Deepthi, B.; Barshilia, Harish C.; Rajam, K.S.; Konchady, Manohar S.; Pai, Devdas; Sankar, Jagannathan; Kvit, A.

doi:10.1016/j.surfcoat.2010.07.050

Cited by 60 publications

(29 citation statements)

References 45 publications

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“…For all samples containing N, only a broad bump is observed, implying that the films are X-ray amorphous. The phenomenon of decreasing crystallinity with increasing addition of another element has previously been observed for WS 2 , and the related MoS 2 , on addition of a wide range of elements, such as N [10], C [9][10][11], Ti [1,2], Cr [4,38] and Au [6,7]. Furthermore, the lack of substrate heating decreases the possibilities of the atoms arranging themselves on arrival at the substrate, meaning that the pure W-S film is also of relatively poor crystallinity.…”

Section: Resultsmentioning

confidence: 72%

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

et al. 2015

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Amorphous W-S-N in the form of thin films has been identified experimentally as an ultra-low friction material, enabling easy sliding by the formation of a WS 2 tribofilm. However, the atomic-level structure and bonding arrangements in amorphous W-S-N, which give such optimum conditions for WS 2 formation and ultra-low friction, are not known. In this study, amorphous thin films with up to 37 at.% N are deposited, and experimental as well as state-of-the-art ab initio techniques are employed to reveal the complex structure of W-S-N at the atomic level. Excellent agreement between experimental and calculated coordination numbers and bond distances is demonstrated. Furthermore, the simulated structures are found to contain N bonded in molecular form, i.e. N 2 , which is experimentally confirmed by near edge X-ray absorption fine structure and X-ray photoelectron spectroscopy analysis. Such N 2 units are located in cages in the material, where they are coordinated mainly by S atoms. Thus this ultra-low friction material is shown to be a complex amorphous network of W, S and N atoms, with easy access to W and S for continuous formation of WS 2 in the contact region, and with the possibility of swift removal of excess nitrogen present as N 2 molecules.

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Section: Resultsmentioning

confidence: 72%

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

et al. 2015

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“…Additional elements are often added to TMD coatings, most commonly C, N and/or some metal, with the main purpose of improving their mechanical properties. [15][16][17][18][19][20][21][22][23] TMDs are also commonly used as lubricant additives, where they may be added either in pure form, as in MoS 2 grease, or as other compounds, that react to form TMD tribofilms in the tribological contact, with MoDTC lubricant additives as the most common example. In recent years, inorganic fullerene-like WS 2 nanoparticles have attracted a large interest as lubricants, and have shown promising results when embedded in solid coatings or porous materials, added to grease or dispersed in oil.…”

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confidence: 99%

Tribochemically Active Ti–C–S Nanocomposite Coatings

Sundberg

Nyberg

Särhammar

et al. 2013

Materials Research Letters

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We demonstrate a new concept of self-adaptive materials, where sulphur is incorporated into TiC/a-C coatings and may be released in, for example, a tribological contact. By reactive sputtering with H 2 S, sulphur goes into the carbide to form a TiC x S y phase in an amorphous carbon matrix. The addition of sulphur lowers the friction against steel. Significantly lower friction is obtained against a tungsten counter-surface, as WS 2 is generated in the contact. Annealing experiments and formation energy calculations confirm that sulphur can be released from TiC x S y . Ti-C-S coatings are thus chemically active in tribological contacts, creating possibilities of new low-friction systems.

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“…Subsequently Cr-WS 2 nanocomposite solid lubricant coatings were deposited on textured and non-textured stainless steel (SS) substrates by magnetron sputtering. The effects of Cr content on the structural, mechanical and tribological properties of Cr-WS 2 nanocomposite solid lubricant coatings have been reported in our previous works (Deepthi et al, 2010a(Deepthi et al, , 2010b. It was observed that Cr-WS 2 coatings prepared at 15-23 at.% Cr exhibited the best mechanical and tribological properties.…”

Section: Introductionmentioning

confidence: 56%

High performance nanostructured Cr-WS<SUB align="right">2 solid lubricant coatings prepared on mechanically textured substrates

et al. 2015

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Cr-WS 2 nanocomposite solid lubricant coatings were prepared on mechanically textured stainless steel substrates. Micron-sized dimples of approximately 10-12 μm depth and 100 × 80 μm 2 area with uniform dimple spacing of 300 μm were created on the substrates using a knurling tool. Substrate surface texturing improved the tribological properties of Cr-WS 2 nanocomposite coatings significantly. Cr-WS 2 nanocomposite coatings prepared on textured steel substrates exhibited a friction coefficient of 0.1 after 28,800 cycles compared to coatings prepared on non-textured substrates which exhibited a friction coefficient of 0.45. The dimpled regions acted as solid lubricant reservoirs and also helped in trapping wear debris. The retention of solid lubricant material in the dimpled region was confirmed using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy studies.

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Structure, morphology and chemical composition of sputter deposited nanostructured Cr–WS2 solid lubricant coatings

Cited by 60 publications

References 45 publications

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

Amorphous W–S–N thin films: The atomic structure behind ultra-low friction

Tribochemically Active Ti–C–S Nanocomposite Coatings

High performance nanostructured Cr-WS<SUB align="right">2 solid lubricant coatings prepared on mechanically textured substrates

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