Reaction mechanisms in organophosphate vapor phase lubrication of metal surfaces

Ren, Daxing; Gellman, Andrew J.

doi:10.1016/s0301-679x(01)00025-1

Cited by 22 publications

(12 citation statements)

References 43 publications

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“…The formation of the butoxy groups from TBT might be preceded by P=S bond scission to give tributyl phosphite, which then undergoes P-O bond scission to give the butoxy groups. This would be consistent with the surface chemistry of trimethyl phosphite and tributyl phosphite, which decompose to produce alkoxy groups on Fe [49][50][51] (scheme 2).…”

Section: Composition Of the Thermal Filmsupporting

confidence: 70%

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

et al. 2006

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The surface reactivity of tributyl thiophosphate on iron surfaces has been studied in situ by attenuated total reflection Fouriertransform infrared spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed reaction and desorption spectroscopies. The results show that at temperatures lower than 373 K the molecule forms a physisorbed layer on the iron substrate. At 373 K a reaction takes place with the formation of an organic layer, together with iron polyphosphate and sulfate. At higher temperatures temperature-programmed desorption results suggest that the mechanism involves P-O bond scission to yield butoxy groups. This could be preceded by P=S bond scission to give tributyl phosphite, which then, in turn, undergoes P-O bond scission to produce butoxy groups. The results obtained following tribological testing are in agreement with those of thermal tests: evidence of polyphosphate and sulfate formation is found.

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Section: Composition Of the Thermal Filmsupporting

confidence: 70%

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

et al. 2006

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“…We believe this reduced level of reactivity results in the absence of an immediate tribological benefit and is related to the byproducts of the surface reaction. The C:P and O:P ratios measured with the uptake of triethyl phosphate suggest that the initial reaction at low exposures of triethyl phosphate involves a degree of P-O bond cleavage, a mechanism also observed on metal surfaces [24]. This observation implies that ethoxy groups are formed on the VC surface.…”

Section: Reactions and Influence Of Alkyl Phosphatesmentioning

confidence: 72%

Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

et al. 2005

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This report presents ultrahigh vacuum measurements of the frictional properties of the non-polar (100) surface of vanadium carbide (VC) as a function of the room temperature uptake and reaction of ethyl acetate, triethyl phosphate, and trimethyl phosphate. Atomic force microscopy, employing a silicon nitride probe tip, has been used to determine the changes in friction and interfacial adhesion as a function of adsorbate uptake. Changes in surface morphology have been monitored with scanning tunneling microscopy while the composition of the surface species formed through the reaction of these adsorbates with the VC surface has been determined by X-ray photoelectron spectroscopy. Adsorption and reaction of ethyl acetate leads to an increase in friction with little change in interfacial adhesion. The adsorption and reaction of triethyl phosphate and trimethyl phosphate have no influence on either the friction or adhesion properties of VC. The observed results are discussed in terms of the surface chemical composition, the extent of surface coverage, and the molecular details of the adsorbed species.

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“…The reaction between TBT and iron was proposed to occur via an initial P=S bond scission to give tributyl phosphite. In accordance with [3,8,11,[17][18][19], this compound successively produced butoxy groups through P-O bond cleavage.…”

Section: Introductionmentioning

confidence: 70%

“…metal-free) additives, such as organosulfur compounds [6], phosphates [6][7][8][9][10][11][12][13][14][15][16], amine phosphates [12], phosphites [11,[17][18][19], phosphorothionates [12][13][14][20][21][22][23][24][25][26], and dithiophosphates [12,21,22,24].…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Triphenyl Phosphorothionate in Lubricant Oil Solution

2009

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Investigating the thermo-oxidative reactivity of anti-wear additives in lubricant oil solution at high temperature can significantly contribute to an understanding of the mechanism of thermal film and tribofilm formation on metal surfaces. In this study, the reactivity of triphenyl phosphorothionate (TPPT) in lubricant oil solution at high temperature (423 and 473 K) has been studied by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. The results show that the TPPT molecule was highly thermally stable and did not completely decompose in oil solution even upon heating at 423 K for 168 h and at 473 K for 72 h. The degradation of the TPPT molecule, which turned out to be a first-order reaction, started taking place after 6 h at both temperatures, leading to the breakage of the P=S bond with the formation of triphenyl phosphate. During these heating experiments, no oil-insoluble compounds were detected. The oxidation of the base oil as a result of the prolonged heating demonstrated that the TPPT molecule did not effectively act as oxidation inhibitor.

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Reaction mechanisms in organophosphate vapor phase lubrication of metal surfaces

Cited by 22 publications

References 43 publications

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

Surface reactivity of tributyl thiophosphate: effects of temperature and mechanical stress

Influence of ethyl acetate and alkyl phosphate adsorption on the frictional properties of VC(100)

Reactivity of Triphenyl Phosphorothionate in Lubricant Oil Solution

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