Rolling contact fatigue using solid thin film lubrication

Danyluk, Mike; Dhingra, Anoop K.

doi:10.1016/j.wear.2011.10.005

Cited by 13 publications

(7 citation statements)

References 8 publications

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“…In the ambient and vacuum tests, the vibration limit correlated with the depletion of the Ti-MoS2 coatings at the contact interface as opposed to the occurrence of ball or rod spall. The phenomena of coating depletion at the interface resulting in high vibration was previously reported by Danyluk and Dhingra for silver coatings tested against M50 rods [38]. Wear tracks created on the rods during the tests in the ambient environment ( Figure 4a,d) were formed from wear of the M50 rod with no evidence of transferred material or tribofilm formation.…”

Section: Tribological (Rcf) Performancesupporting

confidence: 74%

Rolling Contact Performance of a Ti-Containing MoS2 Coating Operating Under Ambient, Vacuum, and Oil-Lubricated Conditions

2019

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Solid lubricant molybdenum disulfide (MoS2) coatings have been frequently used to lubricate mechanisms operating in environments where oil and grease lubrication are ineffective. This work evaluated the rolling contact performance of a Titanium-containing MoS2 coating under humid ambient, vacuum, and oil-lubricated conditions. Weibull analyses of L50 lifetimes of AISI 52100 steel balls coated with a Ti-MoS2 coating paired with uncoated M50 steel rods were determined to be 3.7, 14.5, and 158.6 million cycles in ambient, vacuum, and oil-lubricated environments, respectively. In the ambient and vacuum tests, failures were determined to be associated with the onset of abrasive wear rather than fatigue or spalling. The L50 lifetimes of tests performed in those environments were found to depend upon the wear rate of the coatings on the balls. That is, the Ti-MoS2 functioned as a barrier to the onset of abrasive wear between the steel alloys until the coating was sufficiently worn away. Under oil-lubricated (boundary lubrication) conditions, L50 was found to depend on the durability and composition of tribofilms formed in-situ on the surfaces of the uncoated M50 rods. The tribofilms were comprised of mixtures of MoS2 crystallites and amorphous hydrocarbon (a-C:H). The crystalline MoS2 in the tribofilm originated from the amorphous Ti-MoS2 coating and likely underwent a thermodynamic phase transition as a result of the applied Hertz stress and frictional heating in the contact. The a-C:H in the tribofilm probably originated from a catalytic scission of the polyalphaolefin (PAO) molecules caused by the d-band character of the Mo or Ti in the coating. Overall, the Ti-MoS2-coated balls were effective at extending the operational lifetimes of M50 rods under ambient, vacuum, and oil-lubricated conditions by an order of magnitude.

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Section: Tribological (Rcf) Performancesupporting

confidence: 74%

Rolling Contact Performance of a Ti-Containing MoS2 Coating Operating Under Ambient, Vacuum, and Oil-Lubricated Conditions

2019

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“…RCF life has been shown to be an indicator of film quality with respect to internal stresses and contamination within the context of a large Table I. 12. scale coating process in the range of 60-300 balls coated at once.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

Influence of process parameters on rolling-contact-fatigue life of ion plated nickel–copper–silver lubrication

Danyluk

Dhingra

2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Articles you may be interested inKinetic model for dependence of thin film stress on growth rate, temperature, and microstructure J. Appl. Phys. 111, 083520 (2012); 10.1063/1.4704683Rolling contact fatigue in high vacuum using ion plated nickel-copper-silver solid lubricationThe rotation of ripple pattern and the shape of the collision cascade in ion sputtered thin metal films J. Appl. Phys.In this paper, we present a connection between argon ion flux, element-mixing, and rolling contact fatigue (RCF) life of a thin film nickel-copper-silver lubricant on ball bearings. The film is deposited on the balls using an ion plating process and tested for RCF in high vacuum. The ion flux is measured using a Langmuir probe and the plane stress within the film during deposition is calculated using a thin film model. Experiments reveal that there is an inverse relationship between ion flux and RCF life for most deposition voltage and pressure combinations tested, specifically, 15.5-18.5 mTorr and 1.5-3.5 kV. For voltages up to 2.5 kV, RCF life decreases as ion flux increases due to increased compressive stress within the film, reaching as high as 2.6 GPa. For voltages between 2.5 and 3.5 kV, interlayer mixing of nickel and copper with the silver layer reduces RCF life due to contamination, even as ion flux and corresponding film compressive stress are reduced. A Monte Carlo-based simulation tool, SRIM TM is used to track collision cascades of the argon ions and metal atoms within the coating layers. At process voltages above 2.5 kV we observe elemental mixing of copper and nickel with the silver layer using Auger electron spectroscopy of coated steel and Si 3 N 4 balls. The authors conclude that an ion flux greater than 5.0 Â 10 14 cm À2 s À1 leads to reduced RCF life due to high film stress. In addition, process voltages greater than 2.5 kV also reduce RCF life due to contamination and interlayer mixing of nickel and copper within the silver layer.

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“…The RCF test rig in Figure 1 was assembled using off the shelf components purchased from leading vacuum and mechanical equipment vendors (Danyluk and Dhingra, 2012a). For example, a Kollmorgen TM servo motor (model number AKM21E) is used to rotate the rod.…”

Section: Methodsmentioning

confidence: 99%

“…The first model uses a conservation of mass approach and is based on the work presented in (Higg and Wornyoh, 2008), (Danyluk and Dhingra, 2012a). A third-body mass transfer concept is applied to account for the transport of the film from the ball surface to the rod and race contact surfaces as seen experimentally in Figures 8 and 9.…”

Section: Thin Film Solid Lubrication Modellingmentioning

confidence: 99%