Low-friction, high-endurance, ion-beam-deposited PbMoS coatings

Wahl, Kathryn J.; Seitzman, L. E.; Bolster, R.N.; Singer, I. L.

doi:10.1016/0257-8972(94)02383-2

Cited by 95 publications

(67 citation statements)

References 29 publications

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“…Figure 2 is a HRTEM image of an as-deposited Pb-Mo-S film. The film was dense and uniform in appearance throughout and produced amorphous SAED diffraction patterns (not shown), consistent with earlier x-ray diffraction results [2]. Closer examination of Fig.…”

Section: Resultssupporting

confidence: 75%

“…Pb-Mo-S films were deposited to a thickness of 200 nm on Si (100) substrates using ion beam deposition under conditions known to produce amorphous films with Pb doping concentrations of ~10-15 at.% [2,5].…”

Section: Methodsmentioning

confidence: 99%

“…The addition of Pb during deposition produces amorphous films whose endurance exceeds that of MoS 2 while providing equivalent friction coefficients [2]. Raman analysis suggests that crystalline MoS 2 is formed during sliding against these [2] and PbOalloyed MoS 2 films [3], accounting for the low friction, but how and where this transformation occurs is unclear. Additionally, the Pb-Mo-S films are remarkably wear resistant [4]; how the transformation to MoS 2 influences the Pb-Mo-S film wear is not known.…”

Section: Introductionmentioning

confidence: 99%

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

1998

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Microstructural aspects of wear resistance have been investigated using cross-sectional transmission electron microscopy (TEM) to analyze both as-deposited and worn films. Asdeposited Pb-Mo-S films were virtually amorphous, i.e., show no long range structure. Wear tracks revealed a two-part wear process localized at the sliding surface. First, Pb-Mo-S at the sliding surface was transformed into basal-oriented, crystalline MoS 2 from 1 to 4 monolayers thick. Then, as sliding continued, the MoS 2 layers were detached one or two layers at a time. Evidence for the nanometer scale wear process is presented.

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Section: Resultssupporting

confidence: 75%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

1998

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“…Once the transfer mechanics are understood, one may be able to modify the lubricant chemistry or structure to enhance coating wear life. It has been shown that chemical dopants can be used to improve the endurance of MoS 2 [18,19,20,21], but the mechanisms by which this occurs are unknown. Study of the mechanics of transfer processes may lead to a better understanding of how these additives improve wear life.…”

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confidence: 99%

Quantification of a lubricant transfer process that enhances the sliding life of a MoS2 coating

Wahl

Singer

1995

Tribol Lett

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A lubricant transfer process that enhanced the wear life of a MoS 2 coating has been identified and quantified. A steel ball sliding against a coated steel flat in reciprocating motion produced reservoirs at the turnaround part of the track ends, then emptied them, to provide replenishment similar to what is expected of liquid lubricants. The dynamics of the process were inferred from measurements of material loss and/or buildup in the track and on the ball; measurements were performed with Michelson interferometry and energy dispersive x-ray spectroscopy. MoS 2 is a remarkable solid lubricant. It produces some of the lowest friction coefficients ever measured [1], and it can be used to lubricate sliding contacts at high contact stresses (on the order of GPa) even though its shear strength is only ~25 MPa. In addition, thin coatings of MoS 2 can withstand hundreds of thousands of sliding cycles, having overall wear rates <<1 nm/cycle. Although some of its behavior can be explained in terms of the bulk mechanical properties of MoS 2 (e.g. low friction coefficient in terms of the plasticity/shear strength), the high endurance has never been accounted for. Furthermore, while MoS 2 provides endurant sliding, it is well known that most of the coating is lost early in life, both in sliding [2,3,4,5] and rolling [6]. How, then, does the remaining lubricant sustain sliding?We began this study to learn how a coating, worn heavily early in sliding, was able to endure the remaining 90% of sliding life [7]. But our investigation led to the recognition that the endurance was influenced not only by the coating wear rate but also by a lubricant replenishment process. This

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“…The decrease in the crystallite size of the sample grown at 0.25 W/cm 2 and the later separation of the peaks in the other patterns were caused by the Ti atoms preventing the nucleation and formation of the crystalline phase of WS 2 , thus producing an amorphous film [8]. This phenomenon also occurs in MoS 2 films doped with Ti [22], SbOx [23], Pb [24] and PbO [25].…”

Section: Profilometrymentioning

confidence: 72%

Structure and Properties of Titanium Doped Tungsten Disulfide Thin Films Produced via the Magnetron Co-Sputtering DC Technique

Carmona

Sequeda

2016

Matéria (Rio J.)

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In this work, titanium doped tungsten disulfide thin films (WS 2 -Ti) were deposited on AISI 304 stainlesssteel substrates using the magnetron co-sputtering DC technique. Films were produced with varying titaniumcathode power from 0 to 25 W. The titanium content of the WS 2 structure was determined using energy dispersive spectroscopy (EDS), thereby obtaining a maximum of 10% for the sample grown at 25 W. X-ray diffraction (XRD) results indicated, for the pure sample, the presence of a hexagonal phase of high intensity on the (103) plane. However, with the addition of titanium, the WS 2 crystallinity was reduced; nevertheless, when the titanium content was equal to 10%, nanocomposite formation was promoted. This effect was observed in TEM (transmission electron microscopy) images. Finally, the tribological behavior was determined using a ball on disk (BOD) test. With this method, friction coefficient curves were obtained with respect to the number of cycles, allowing the measurement of friction coefficient values of 0.1 for the pure sample and 0.15 for the sample grown at 5 W. Because of the low thickness of the samples, all of them failed during the first cycles.

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Low-friction, high-endurance, ion-beam-deposited PbMoS coatings

Cited by 95 publications

References 29 publications

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

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

Quantification of a lubricant transfer process that enhances the sliding life of a MoS2 coating

Structure and Properties of Titanium Doped Tungsten Disulfide Thin Films Produced via the Magnetron Co-Sputtering DC Technique

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