Low-Temperature, Shear-Induced Tribofilm Formation from Dimethyl Disulfide on Copper

Furlong, Octavio Javier; Miller, Brendan; Kotvis, Peter V.; Tysoe, Wilfred T.

doi:10.1021/am101149p

Cited by 51 publications

(54 citation statements)

References 34 publications

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“…The experiment was initiated by rst rubbing the clean copper surface for $70 cycles. 61 This created an initial wear track (about 100 mm wide) and resulted in a runin period during which the friction decreased from an initial value of $0.8 to a lower and steady value of $0.52. Thus, any further changes in friction coefficient are due to DMDS exposure and not to any evolution in the nature of the contact.…”

Section: Ambient-temperature Tribochemistry Of Dimethyl Disulfide On mentioning

confidence: 99%

Shear and thermal effects in boundary film formation during sliding

et al. 2014

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A prerequisite for understanding mechano-and tribochemical reaction pathways is that the interface be in thermodynamic equilibrium and that the temperature be well defined. It is suggested that this occurs in two regimes: when the surfaces are only slightly perturbed during sliding, leading to negligible frictional heating, and when the surface temperatures are very high ($1000 K), in the so-called extreme pressure regime. The tribochemistry occurring in each regime is discussed in terms of the elementary steps leading to tribofilm formation, namely (i) a reaction of the additive or gas-phase lubricant on the surface to form an adsorbed precursor, (ii) decomposition of the molecular precursor, (iii) a process that causes the formation of a tribofilm that (iv) regenerates a clean surface that allows this tribochemical cycle to continue to form a thicker film. These steps are thermally driven in the extreme-pressure regime, while under milder conditions, they are induced by interfacial shear. In intermediate situations, the processes are likely to be a combination of those occurring at the extrema.

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Section: Ambient-temperature Tribochemistry Of Dimethyl Disulfide On mentioning

confidence: 99%

Shear and thermal effects in boundary film formation during sliding

et al. 2014

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“…51 However, recent works have shown that tribochemical reactions can take place even though the temperature raise during sliding is negligible or limited and highlighted the primary role of mechanical stresses in the activation of chemical reactions. 41,[52][53][54][55][56][57][58] Our calculations at zero-applied temperature provide a further evidence that mechanical stresses can promote chemical reactions. In particular, we show that the increased enthalpy under compression can destabilize the confined molecules and promote their dissociation.…”

Section: Discussionmentioning

confidence: 52%

“…Such temperature increase has been also proposed to produce local excitations, “magama plasma,” that decay rapidly into a local heating of the surface . However, recent works have shown that tribochemical reactions can take place even though the temperature raise during sliding is negligible or limited and highlighted the primary role of mechanical stresses in the activation of chemical reactions …”

Section: Discussionmentioning

confidence: 99%

First principles study of organophosphorus additives in boundary lubrication conditions: Effects of hydrocarbon chain length

Loehlé

Righi

2017

Lubrication Science

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We apply first principle calculations to investigate the effects of the hydrocarbon chain length in additive molecules under boundary lubrication conditions. In these conditions, occurring in high‐pressure applications, the thickness of the oil film becomes extremely thin, and the additive molecules remain confined between the two solid surfaces in contact. We consider two types of organophosphorous additives having the same phosphite group but hydrocarbon chains of different lengths. By comparing the molecular behavior under uniaxial stress applied, we elucidate the atomistic mechanisms that control the molecular capacity of maintaining an interfacial spacing under compression and the load‐induced molecular dissociation. This insight is relevant not only for a rational design of lubricant additives but also to provide understanding on the activation mechanisms of tribochemical reactions.

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“…The normal load of 20 N corresponding to a maximum Hertzian pressure of 1.61 GPa, sliding velocity of 0.13 m s −1 , and total sliding distance of 4800 m were applied for all tests. In this study, a stressed‐shearing effect on the tribofilm formation was mainly investigated and the influence of temperature was not considered . All the tests were performed at room temperature to simulate the cold‐start conditions of engine.…”

Section: Methodsmentioning

confidence: 99%

“…In order to clarify the intrinsic relationship between macroscopic tribological performance and graphene presence, reciprocating tribo‐wear testing was carried out using a commercial engine oil mixed with GNP. In this study, we mainly consider the stressed‐shearing effect on the tribofilm formation without much influence of temperature . The focus is on understanding the effect of GNP additions on tribological capability and resultant tribofilm formation.…”

Section: Introductionmentioning

confidence: 99%

Unusual Competitive and Synergistic Effects of Graphite Nanoplates in Engine Oil on the Tribofilm Formation

Pham

Wan

Tieu

et al. 2019

Adv Materials Inter

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To exploit the improved efficiency from formulated oil modified with graphite nanoplates (GNP), it is important to understand how GNP behave alongside conventional additives such as zinc dialkyl dithiophosphates (ZDDP). The results in this work demonstrate unusual tribological responses of engine oil due to GNP additions, which cannot be explained by the traditionally low shearing mechanism between graphene layers in GNP. A competitive and synergistic effect of GNP on tribofilm formation is proposed for this unusual friction and wear behavior. The presence of GNP modifies the tribofilm formation and spontaneously creates alternate hard and soft regions from the microscopic view of the surface. At low concentrations (≤0.05 wt%), graphene is formed by shear‐assisted exfoliation of GNP and intermixed with intermediate oxide region. Due to its random orientation, graphene produces mechanical reinforcement of the tribofilm, but low shear yielding is not achieved. This gives rise to high friction but low wear conditions. At higher concentrations (>0.05 wt%), GNP align with their hexagonal sheets parallel to the surface to promote low‐shear sliding, but wear increases. This is due to GNP clumping together which makes them less effective at forming graphene and providing stable reinforcement of the tribofilm.

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Low-Temperature, Shear-Induced Tribofilm Formation from Dimethyl Disulfide on Copper

Cited by 51 publications

References 34 publications

Shear and thermal effects in boundary film formation during sliding

Shear and thermal effects in boundary film formation during sliding

First principles study of organophosphorus additives in boundary lubrication conditions: Effects of hydrocarbon chain length

Unusual Competitive and Synergistic Effects of Graphite Nanoplates in Engine Oil on the Tribofilm Formation

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