Modelling Tribochemical Reactions of Lubricants in the UHV Analytical Tribometer

Martin, Jean‐Michel; Philippon, David; Matta, C.; Mogne, Thierry Le; Boehm, Matthieu

doi:10.2474/trol.10.21

Cited by 4 publications

(6 citation statements)

References 13 publications

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“…Gas phase lubrication (GPL) with in situ surface analysis Tribochemical reactions of phosphite and polysulphide additives on steel surfaces are investigated using a specic Environmentally Controlled Analytical Tribometer (ECAT) dedicated to GPL. 16,20,47 This specic device is composed of a reciprocating pin-on-at tribometer with a movable pin being connected to a brushless motor located in a Ultra High Vacuum (UHV) chamber. The temperature of the friction pair can be controlled from À100 C to 600 C thanks to the at holder equipped with both a nitrogen cooling and a heating system.…”

Section: Systems and Methodsmentioning

confidence: 99%

“…Tribochemical reactions of phosphite and polysulphide additives on steel surfaces are investigated using a specific Environmentally Controlled Analytical Tribometer (ECAT) dedicated to GPL [16,20,47]. This specific device is composed of a reciprocating pin-on-flat tribometer with a movable pin being connected to a brushless motor located in a Ultra High Vacuum (UHV) chamber.…”

Section: Gas Phase Lubrication (Gpl) With In Situ Surface Analysismentioning

confidence: 99%

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A comparative study on the functionality of S- and P-based lubricant additives by combined first principles and experimental analysis

et al. 2016

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Sulfur and phosphorus are key elements for the functionality of lubricant additives used in extreme pressure applications, such as synchronizer systems in cars. To understand their mechanism of action we combine first principles calculations and gas phase lubrication experiments. The surface spectroscopy analysis performed in situ after the tribological test indicates that iron sulfide (phosphide) is formed by rubbing steel-on-steel in the presence of organo-sulfur (-phosphorus) molecules. We, thus, study the effects of elemental sulfur and phosphorus on the interfacial properties of iron by spin-polarized density functional theory calculations. The results show that both the elements are very effective in reducing the adhesion and shear strength of iron. Sulfur is predicted to be more effective than phosphorus, especially at high pressure. Gas phase lubrication experiments confirm these results, indicating that the friction coefficient of iron-sulphide is lower than that of iron-phosphide and both S and P dramatically reduce the friction of steel-on-steel. These results indicate that the release of elemental sulfur and phosphorus may be the key mechanism to controlling the tribological properties of the metal interface and elucidate that the underling microscopic phenomenon is metal passivation. © 2016 The Royal Society of Chemistry

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Section: Systems and Methodsmentioning

confidence: 99%

Section: Gas Phase Lubrication (Gpl) With In Situ Surface Analysismentioning

confidence: 99%

A comparative study on the functionality of S- and P-based lubricant additives by combined first principles and experimental analysis

et al. 2016

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“…Additional details on the operation of the ECAT device are given elsewhere. 10,13 Heavy molecular weight compounds like triphenylphosphite are used as additives in commercial lubricants due to their solubility in oil, provided by the presence of long carbon chains. However, it is difficult to evaporate such heavy molecular weight additives in UHV, 10 À9 hPa.…”

Section: Thermally-controlled Adsorption Experiments and In Situ Xps ...mentioning

confidence: 99%

“…12 Gas Phase Lubrication (GPL) using an environmentally controlled analytical tribometer (ECAT) is able to simulate the boundary lubrication regime, where the additive molecules interact with the surfaces in contact without any external contamination. 13 This simplied experimental approach opens the way to a combined theoretical analysis based on atomistic simulations. Indeed, we have recently coupled rst principles calculations and gas phase lubrication experiments to elucidate the effects of the surface termination on the adhesion and friction of nanocrystalline diamond (NCD) coatings 14 and iron interfaces.…”

Section: Introductionmentioning

confidence: 99%

Trimethyl-phosphite dissociative adsorption on iron by combined first-principle calculations and XPS experiments

et al. 2015

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The reaction of trimethyl-phosphite, TMPi, with a clean Fe(110) surface has been investigated by ab initio calculations. The most stable configurations and energies are identified for both molecular and dissociative adsorption. The calculated reaction energies indicate that dissociation is energetically more favorable than molecular adsorption and we provide a description of the dissociation path and the associated energy barrier. In situ XPS analysis of adsorbed TMPi on metallic iron confirmed molecular chemisorption and dissociation at high temperature. These results shed light on the mechanism of phosphorus release from organophosphites at the iron surface, which is important for the functionality of these phosphorus-based additives, included in lubricants for automotive applications

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“…The analyzed retrieval cohort illustrated local defect features that correspond to different basic wear mechanisms defined in the standard DIN 50320:1979‐12 and refined submechanisms (Dienwiebel, ; Stemmer & Fischer, ). In order to define countermeasures that prevent the distinguished damages, an understanding of the multifactorial interdependencies on macro‐, micro‐, and nanoscale of the tribological taper system is of uppermost importance.…”

Section: Resultsmentioning

confidence: 99%

In vivo corrosion and damages in modular shoulder prostheses

et al. 2019

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Wear and corrosion at taper junctions of orthopaedic endoprostheses remain of great concern and are associated with adverse clinical reactions. Whereas tribocorrosion of hip tapers was extensively investigated, there is only little knowledge regarding the clinical performance of modular total shoulder prostheses. This retrieval study evaluated 35 modular taper junctions of anatomical shoulder explants using stereomicroscopy, confocal microscopy, as well as optical and scanning electron microscopy to determine the damage modes as well as the effects of taper topography and alloy microstructure. Among all humeral head tapers, 89% exhibited material degradation. Different overlapping wear mechanisms were identified such as plastic deformation, adhesive material transfer, microploughing, and fretting damage.Only CoCrMo cast alloy heads showed a susceptibility to electrochemically dominated fretting in comparison to CoCrMo wrought alloy. Moreover, corundum blasted stem tapers show a significantly increased incidence rate for microploughing. To date, this is the most comprehensive study on the damage types of modular taper junctions of anatomical shoulder arthroplasty proving the existence of fretting even on less weight-bearing implants. This study revealed critical fretting factors, such as the surface finish and the alloy type that are essential for the development of countermeasures that avoid any taper corrosion.

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Modelling Tribochemical Reactions of Lubricants in the UHV Analytical Tribometer

Cited by 4 publications

References 13 publications

A comparative study on the functionality of S- and P-based lubricant additives by combined first principles and experimental analysis

A comparative study on the functionality of S- and P-based lubricant additives by combined first principles and experimental analysis

Trimethyl-phosphite dissociative adsorption on iron by combined first-principle calculations and XPS experiments

In vivo corrosion and damages in modular shoulder prostheses

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