Nanostructural Aspects of Wear in Ion-Beam Deposited Pb-Mo-S Films

Dunn, Derren; Wahl, Kathryn J.; Singer, I. L.

doi:10.1557/proc-522-451

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…This is consistent with previous studies showing that even fully amorphized MoS x coatings retained their low friction properties [10,12]. This is not surprising, as amorphous MoS x [3,38] as well as amorphous MoS x containing PbO [39] or Pb [40][41][42] have been shown to recrystallize to form MoS 2 under sliding stresses. While it had been reported earlier that amorphization of MoS 2 increased friction [2,28], those results have been explained by contamination effects [2,11].…”

Section: Discussionsupporting

confidence: 92%

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Effects of ion implantation on microstructure, endurance and wear behavior of IBAD MoS2

Wahl

Dunn

Singer

2000

Wear

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Section: Discussionsupporting

confidence: 92%

“…However, we don't believe that simply amorphizing the MoS 2 coatings is likely to reduce their wear resistance. Our amorphous, Pb-doped Mo-S coatings [40][41][42] showed remarkable wear resistance (as little as 40 nm wear in 30000 reciprocating sliding cycles), suggesting that amorphization alone does not control wear of these coatings.…”

Section: Discussionmentioning

confidence: 92%

Effects of ion implantation on microstructure, endurance and wear behavior of IBAD MoS2

Wahl

Dunn

Singer

2000

Wear

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“…55 Some evidence suggests that sliding a MoS 2 -containing transfer film against a recrystallized track might be all that is required. 51,56 The recent work by Hu and co-workers 52 leaves the question open: Some noncontacting regions of the frozen interface have no transfer film, whereas both the contacting and gap regions have similar numbers of transformed layers. New materials such as fullerene-like MoS 2 and WS 2 particles are also of great interest, as they too can provide very low-friction sliding.…”

Section: Interfacial Film Formationmentioning

confidence: 99%

Observing Interfacial Sliding Processes in Solid–Solid Contacts

Wahl¹,

Sawyer²

2008

MRS Bull.

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Directly seeing into a moving contact is a powerful approach to understanding how solid lubricants develop low-friction, long-lived interfaces. In this article, we present optical microscopy and spectroscopy approaches that can be integrated with friction monitoring instrumentation to provide real-time, in situ evaluation of solid lubrication phenomena. Importantly, these tools allow direct correlation of common tribological events (such as variations in friction and wear) with the responsible sliding-induced mechanical and chemical phenomena. We demonstrate the utility of in situ approaches with applications to a variety of thin-film solid lubricants.what is happening within the sliding solid-solid interfaces has limited both the modeling of contact processes and predictive engineering to improve the performance of sliding components.Solid lubrication of an interface requires both low, stable friction and development of low-wear conditions. A common strategy for solid lubrication is surface modification with a lubricant-containing coating. Unfortunately, because coatings are typically worn away during operation, their lifetimes are limited. This has motivated alternative strategies to resupply lubricants during operation (e.g., delivery of solid lubricant powders 1 or in situ formation of solid lubricants from the gas phase 2-7 ).Because sliding occurs in a buried interface, it is challenging to determine what materials processes are actively enabling stable performance. Similarly, unknown interfacial phenomena cause friction instabilities and debris generation to occur, and wear can go undetected. This article highlights recent advances of in situ tribology instrumentation and approaches that allow observation and quantification of the mechanical and chemical processes influencing friction and wear in solidlubricated contacts. These new approaches allow for an understanding of issues such as: What causes friction instabilities? How do chemistry and mechanics combine to provide low friction? How does varying the ambient environment change the interfacial film morphology and rheology? How do crystal structure and size influence lubricant performance?Several benefits can be obtained by performing tribological measurements in situ in the test environment. First, it simplifies the correlation between friction data and interface events. Second, it eliminates the need to remove the sample from the test environment and thus greatly reduces the risk of surface contamination. Perhaps most importantly, much of the highly speculative nature of deriving explanations for friction changes can be eliminated from direct observation of contact events in real time.

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