Tribological performance of MoS2 coatings in liquid helium and at high loads

Lingertat, J.; Gradt, Thomas; Hathiramani, D.; Junghanns, P.; Laux, M.; Meine, K.; Schauer, F.; Schneider, T.

doi:10.1016/j.fusengdes.2009.01.069

Cited by 11 publications

(14 citation statements)

References 6 publications

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“…In this paper, we shall first verify our approach by comparing our numerical calculation with previous measurements and then we would like to examine the possible low resistance states for MoS 2 solid films via tuning the activation volume. The latter effect could be similar to those several thousand load cycles (subjected to the design value: 1.5 × 10 6 MPa) during the expected operating cycles of W7-X (Briani et al , 2011; Dudek et al , 2009; Fellinger et al , 2011; Gradt et al , 2008; Hathiramani et al , 2009; Koch et al , 2007; Lingertat et al , 2009).…”

Section: Introductionsupporting

confidence: 67%

“…Once the superconducting (SC) coils are energized, the pad is compressed against the counter-face with forces up to 1.5 × 10 6 N (design value). The maximum force is reached when the magnetic field on the plasma axis is 3 tesla (Briani et al , 2011; Dudek et al , 2009; Fellinger et al , 2011; Gradt et al , 2008; Hathiramani et al , 2009; Koch et al , 2007; Lingertat et al , 2009).…”

Section: Introductionmentioning

confidence: 99%

“…To be specific, static friction peaks and stick-slip events during sliding of a pad (in NSE) against its counter-face will cause some disturbances to the magnet system and then must be avoided. Moreover, for pure metallic contact, due to the high load, large static friction at the onset of sliding will be accompanied by a loud noise and a shock running through the test equipment (Briani et al , 2011; Dudek et al , 2009; Fellinger et al , 2011; Gradt et al , 2008; Hathiramani et al , 2009; Koch et al , 2007; Lingertat et al , 2009). To make sure a rather smooth and low friction sliding of the two NSE counterparts in W7-X, a (solid) lubricant must be used.…”

Section: Introductionmentioning

confidence: 99%

“…To make sure a rather smooth and low friction sliding of the two NSE counterparts in W7-X, a (solid) lubricant must be used. Given the extreme operational conditions at the location of the NSEs ( T = 4.2 K, vacuum, high compression force), the best choice is effectively reduced to one lubricant only, molybdenum disulfide (MoS 2 ) (Briani et al , 2011; Dudek et al , 2009; Fellinger et al , 2011; Gradt et al , 2008; Hathiramani et al , 2009; Koch et al , 2007; Lingertat et al , 2009). Other nuclear fusion facilities (Christoph et al , 2014; Doshi et al , 2006; Rigato et al , 2009) selected the same material coating considering similar issues.…”

Section: Introductionmentioning

confidence: 99%

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Low friction states for thin solid lubricant film of MoS₂

Chu

2018

ILT

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Purpose During the operation of Wendelstein 7-X (W7-X), any mechanical disturbance such as stick-slip may cause quenching of superconducting (SC) coils. The friction behavior of MoS2 lubrication (thin film) for narrow support elements between the SC coils in W7-X is rather important, as there is a design requirement for a coefficient of friction (COF) 0.05 between the sliding surfaces to control the stress contribution (from friction). Design/methodology/approach The author has carried out intensive calibrations or verifications using verified models considering previous friction tests on various samples which measured the COF in 4.2 K, 77 K and room temperature conditions (at high vacuum) to simulate the actual working condition. Findings The author has given useful explanations and diagnosis for previous anomalous scattered data. To improve the performance of MoS2, the author has predicted its better COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS2 thin films considering the long-term operation requirement W7-X. Originality/value In this paper, the author has adopted Eyring’s approach to predict the low COF (0.002 via tuning of the activation volume), which could be a superlubricating state for MoS2 thin films considering the long-term operation requirement W7-X. Finally, some recent progresses about the possible few-layer MoS2 role in the electromagnetic loads have been provided.

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Section: Introductionsupporting

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low friction states for thin solid lubricant film of MoS₂

Chu

2018

ILT

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“…For application in Wendelstein 7-X, PVD-MoS 2 -coatings were tested in cryogenic media 10,11) . Most of the tests were carried out with cryotribometers which are described in Ref.…”

mentioning

confidence: 99%

Tribological Behaviour of Solid Lubricants in Hydrogen Environment

Gradt

Theiler

2011

Tribology Online

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For further development of hydrogen technology, it is necessary to have a sufficient number of materials for safe and reliable operation available. Frictional contacts exposed to hydrogen, are critical because of vanishing protective oxide layers in the presence of a chemical reducing environment. Furthermore, liquid lubricants are often not applicable, because of purity requirements, or very low temperatures in the case of liquid hydrogen. Thus, for numerous tribosystems in hydrogen technology, solid lubrication is the only possible method for reducing friction and wear. Therefore, investigations on the tribological behaviour of friction reducing materials, such as PTFE, graphite, DLC and MoS 2 , in inert and hydrogen environment were carried out. The results show that solid lubricants, applied as coatings or as components in polymer composites, are able to reduce friction and wear in gaseous as well as in liquid hydrogen. However, some materials are very sensitive to the environmental medium.

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