Extreme friction reductions during initial running-in of W–S–C–Ti low-friction coatings

Nyberg, Harald; Sundberg, Jill; Särhammar, Erik; Gustavsson, Fredrik; Kubart, Tomáš; Nyberg, Tomas; Jansson, Ulf; Jacobson, Staffan

doi:10.1016/j.wear.2013.01.065

Cited by 49 publications

(24 citation statements)

References 54 publications

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“…The amount of WS 2 is however not directly connected to friction. This is in agreement with previous studies showing that WS 2 tribofilms only a few tens of nm thick can provide very low friction [8][9][10]. Still, there must be a continuous presence of WS 2 in the contact area.…”

Section: Chemistry Of Worn Surfacessupporting

confidence: 93%

“…The first 500 cycles are disregarded to remove possible differences in running-in behaviour. Such differences have been observed in W-S-C and W-S-C-Ti coatings [10], and a similar tendency can be seen in these data, where increased N content led to an increase in friction during the first cycles. It is likely that this is related to the lower W and S content and the presence of a hard nitride phase.…”

Section: Tribological Performancesupporting

confidence: 85%

“…An increase in N content also means a decrease in the W and S contents. It has been observed in previous studies that if a metal is used as alloying element in WS 2 coatings, it can react to form metal oxides that make up part of the tribofilm [9,10], Contrastingly, the oxides of N are gases and should leave the contact if formed. Nitrogen should thus mainly hinder the tribofilm formation by decreasing the concentration of W and S.…”

Section: Coating Materialsmentioning

confidence: 99%

“…However, the added element also affects the tribofilm formation. The addition of a second metal can have a detrimental effect on the sliding behaviour, as the formed tribofilms consist largely of metal oxides [9,10]. Nonmetals like N and C, on the other hand, disrupt the crystalline structure of WS 2 without forming disturbing compounds in the tribofilms, thus allowing for low-friction sliding.…”

Section: Introductionmentioning

confidence: 99%

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Influence of composition, structure and testing atmosphere on the tribological performance of W–S–N coatings

Sundberg

Nyberg

Särhammar

et al. 2014

Surface and Coatings Technology

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W-S-N coatings deposited by reactive magnetron sputtering offer the possibility of ultra-low friction in unlubricated sliding. In this work, W-S-N coatings of different composition and structure have been deposited, characterised and evaluated with respect to the tribological performance and tribofilm formation. The composition was varied by changing the flow of N 2 into the deposition chamber, leading to N contents ranging from 0 to 47 at.%. W-S-N coatings deposited without substrate heating are amorphous, while substrate heating results in coatings containing nanocrystalline tungsten sulphide (WS x ) for low N contents, and nanocrystalline tungsten nitride (W y N) at a high N content. The coatings were tribologically tested against steel balls in four different atmospheres-dry N 2 , dry air, humid N 2 and humid air-to study the effects of atmospheric O 2 and H 2 O both separately and simultaneously. In dry N 2 , all coatings exhibited an excellent performance with very low friction (μ ≈ 0.02) and wear. Notably, this included the N-richest and hardest coating, containing nanocrystalline W y N and only 13 at.% of S. The friction and wear increased on changing the atmosphere, in the order of dry airhumid N 2 -humid air. In these three non-inert atmospheres, the friction and wear also increased with increasing N content of the coating. It is thus concluded that the presence of O 2 , the presence of H 2 O, and a high N content (i.e., low W and S contents) are three factors increasing the risk of high friction and wear, especially when occurring together. Raman spectroscopy mapping of the contact surfaces on the coatings and the balls showed that low friction and wear is connected to the presence of WS 2 tribofilms in the contact, and that the three previously mentioned factors affect the formation and function of this tribofilm.

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Section: Chemistry Of Worn Surfacessupporting

confidence: 93%

Section: Tribological Performancesupporting

confidence: 85%

Section: Coating Materialsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of composition, structure and testing atmosphere on the tribological performance of W–S–N coatings

Sundberg

Nyberg

Särhammar

et al. 2014

Surface and Coatings Technology

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“…This possibility was e.g., explored in the W-S-C system, where low friction coefficients are observed, due to a spontaneous formation of a self-lubricating WS 2 film in the sliding interface. [16][17][18][19][20][21][22] In Ti-doped WS 2 films, Ti induces a dramatic change in the microstructure by making it amorphous with well-dispersed nanocrystalline precipitates. 23 These films show improved tribological properties compared to pure WS 2 coatings and a low friction due to WS 2 formation in the contact.…”

Section: Introductionmentioning

confidence: 99%

Formation of 2D transition metal dichalcogenides on TiC_1−xA_x surfaces (A = S, Se, Te): A theoretical study

et al. 2013

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Using first principle density functional calculations, we study the formation of 2D transition metal dichalcogenides (TMDs) on TiC 1Àx A x , (A 5 S, Se, and Te) surfaces. We examine the structural misfits between chalcogen-containing TiC and different TMDs and demonstrate that the conditions for formation of TMDs are fulfilled in TiC 1Àx A x . We also demonstrate the influence of chalcogens on the cohesive properties and electronic structure of the carbides. We find that they react with W and form W-dichalcogenides. In the experimentally reported Ti-C-S nanocomposite coatings, the carbide grains are embedded in an amorphous carbon matrix. We discuss here the role of this matrix in the reaction. We propose that TiC 1Àx Te x and TiC 1Àx Se x are the favorable sources for dichalcogenide formation and suggest an alternative way to produce 2D materials in general. Furthermore, we argue that using Ti-C-Te or Ti-C-Se in nanocomposite coatings may be more advantageous for tribological applications than that of Ti-C-S.

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Effects of Mo Single‐Layer Thickness on Microstructure and Tribological Behavior of WS_x/Mo/a‐C/Mo Multilayer Films

Zheng

Wang

Wang³

et al. 2021

Adv Eng Mater

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WS2/a‐C multilayer films exhibit good friction reduction but relatively low hardness and load‐bearing capacity. To further enhance the tribological properties of WS2/a‐C films, Mo layers with different thicknesses are introduced into WSx/a‐C multilayer films to fabricate WSx/Mo/a‐C/Mo multilayer films by magnetron sputtering. The microstructure and tribological properties of the films are characterized by X‐ray diffractometry, scanning electron microscopy, nanoindentation, and ball‐on‐disk tribotesting. The results show that the WSx/Mo/a‐C/Mo multilayer films have better mechanical and tribological properties than WSx/a‐C multilayer films. With increasing Mo single‐layer thickness, the hardness of the multilayer films initially increases and then decreases slightly; moreover, an increased elastic modulus and decreased adhesion are observed. The multilayer film with an Mo single‐layer thickness of 2 nm demonstrates the optimal set of comprehensive properties (i.e., a maximum hardness (H)/elastic modulus (E) ratio of 0.0793, H3/E2 ratio of 0.0812 GPa, binding force of 30.4 N, minimum friction coefficient of 0.187, and wear rate of 1.01 × 10−14 m3 N−1 m−1).

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Extreme friction reductions during initial running-in of W–S–C–Ti low-friction coatings

Cited by 49 publications

References 54 publications

Influence of composition, structure and testing atmosphere on the tribological performance of W–S–N coatings

Influence of composition, structure and testing atmosphere on the tribological performance of W–S–N coatings

Formation of 2D transition metal dichalcogenides on TiC_1−xA_x surfaces (A = S, Se, Te): A theoretical study

Effects of Mo Single‐Layer Thickness on Microstructure and Tribological Behavior of WS_x/Mo/a‐C/Mo Multilayer Films

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Extreme friction reductions during initial running-in of W–S–C–Ti low-friction coatings

Cited by 49 publications

References 54 publications

Influence of composition, structure and testing atmosphere on the tribological performance of W–S–N coatings

Influence of composition, structure and testing atmosphere on the tribological performance of W–S–N coatings

Formation of 2D transition metal dichalcogenides on TiC1−xAx surfaces (A = S, Se, Te): A theoretical study

Effects of Mo Single‐Layer Thickness on Microstructure and Tribological Behavior of WSx/Mo/a‐C/Mo Multilayer Films

Contact Info

Product

Resources

About

Formation of 2D transition metal dichalcogenides on TiC_1−xA_x surfaces (A = S, Se, Te): A theoretical study

Effects of Mo Single‐Layer Thickness on Microstructure and Tribological Behavior of WS_x/Mo/a‐C/Mo Multilayer Films