Antiwear Film Formation by ZnDTP, Detergent, and Dispersant Components of Passenger Car Motor Oils

Yamaguchi, E. S.; Roby, S. H.; Francisco, M. M.; Ruelas, Samantha; Godfrey, Douglas

doi:10.1080/10402000208982569

Cited by 21 publications

(8 citation statements)

References 4 publications

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“…This decrease indicates either the formation of a conducting carbon fi lm or the interruption of the chemical adsorption of ZDDP, detergents and dispersants responsible for forming electrically insulating fi lm 34,35 onto the surface or both. Usually, better fi lm formation resulted in less wear.…”

Section: Discussionmentioning

confidence: 99%

“…The carbon observed here is also likely associated with the dispersants, which also form fi lms on the surface. 34,35 Note that AES cannot distinguish between carbon from an elemental source, such as CB, and carbon from organic compounds. An AES profi le of the bright spots on the surface found primarily an iron oxide fi lm on top of an iron substrate, which supports the above presumption of these being wear particles.…”

Section: Surface Analysesmentioning

confidence: 99%

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Soot–additive interactions in engine oils

O׳Neill

Simko

et al. 2009

Lubrication Science

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Soot is known to cause engine wear. In this work, we focus on how engine oil formulation affects sootrelated wear, and how the lubricant-derived anti-wear fi lm changes when soot is present. Friction and wear experiments of fully and partially formulated diesel engine oils (containing basestock, dispersants and viscosity modifi ers) are conducted with a ball-on-disk rig in the presence of carbon black (CB) as a soot surrogate. The friction coeffi cient was largely unaffected by CB dispersed in the oils, but electrically insulating fi lm formation, an indication of the formation of anti-wear fi lms, was decreased. Wear on the disk was found to either remain the same or decrease when CB was present, depending on the oil formulation. An examination of the lubricant-derived fi lms using Raman and Auger electron spectroscopies found that the presence of more abundant amorphous carbon and lesser amounts of anti-wear fi lm components on the surface was associated with higher wear.

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Section: Discussionmentioning

confidence: 99%

Section: Surface Analysesmentioning

confidence: 99%

Soot–additive interactions in engine oils

O׳Neill

Simko

et al. 2009

Lubrication Science

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“…Both suspension. The phosphate is added in the form of zinc dialkyldithiophosphate as an antioxidant and antiwear additive (62,63). Thus, whenever Ca and phosphate appear in the same particle, it is highly likely that at least a portion of the particle originated from oil.…”

Section: Carbon Class 1 (Ec-ca-po3)mentioning

confidence: 99%

Determination of Single Particle Mass Spectral Signatures from Light-Duty Vehicle Emissions

Sodeman

Toner

Prather

2005

Environ. Sci. Technol.

137

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In this study, 28 light-duty gasoline vehicles (LDV) were operated on a chassis dynamometer at the California Air Resources Board Haagen-Smit Facility in El Monte, CA. The mass spectra of individual particles emitted from these vehicles were measured using aerosol time-of-flight mass spectrometry (ATOFMS). A primary goal of this study involves determining representative size-resolved single particle mass spectral signatures that can be used in future ambient particulate matter source apportionment studies. Different cycles were used to simulate urban driving conditions including the federal testing procedure (FTP), unified cycle (UC), and the correction cycle (CC). The vehicles were selected to span a range of catalytic converter (three-way, oxidation, and no catalysts) and engine technologies (vehicles models from 1953 to 2003). Exhaust particles were sampled directly from a dilution and residence chamber system using particle sizing instruments and an ATOFMS equipped with an aerodynamic lens (UF-ATOFMS) analyzing particles between 50 and 300 nm. On the basis of chemical composition, 10 unique chemical types describe the majority of the particles with distinct size and temporal characteristics. In the ultrafine size range (between 50 and 100 nm), three elemental carbon (EC) particle types dominated, all showing distinct EC signatures combined with Ca, phosphate, sulfate, and a lower abundance of organic carbon (OC). The relative fraction of EC particle types decreased as particle size increased with OC particles becoming more prevalent above 100 nm. Depending on the vehicle and cycle, several distinct OC particle types produced distinct ion patterns, including substituted aromatic compounds and polycyclic aromatic hydrocarbons (PAH), coupled with other chemical species including ammonium, EC, nitrate, sulfate, phosphate, V, and Ca. The most likely source of the Ca and phosphate in the particles is attributed to the lubricating oil. Significant variability was observed in the chemical composition of particles emitted within the different car categories as well as for the same car operating under different driving conditions. Two-minute temporal resolution measurements provide information on the chemical classes as they evolved during the FTP cycle. The first two minutes of the cold start produced more than 5 times the number of particles than any other portion of the cycle, with one class of ultrafine particles (EC coupled with Ca, OC, and phosphate) preferentially produced. By number, the three EC with Ca classes (which also contained OC, phosphate, and sulfate) were the most abundant classes produced by the nonsmoking vehicles. The smoker category produced the highest number of particles, with the dominant classes being OC comprised of substituted monoaromatic compounds and PAHs, coupled with Ca and phosphate, thus suggesting used lubricating oil was associated with many of these particles. These studies show, by number, EC particles dominate gasoline emissions in the ultrafine size range particularlyforthe low...

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“…A great deal of experimental study has been directed toward understanding the nature of the antiwear properties exhibited by ZDDP additives. 1,2,[10][11][12][13][14] It is generally accepted that these additives decompose under engine conditions, i.e., high tem-peratures and pressures, and that the decomposition products react to form a zinc poly(thio)phosophate film. [15][16][17][18][19][20] The exact chemical composition of the film is not known, and it is possible that a wide variety of films exist depending upon the specific conditions under which they are formed in the engine.…”

Section: Introductionmentioning

confidence: 99%

“…A great deal of experimental study has been directed toward understanding the nature of the antiwear properties exhibited by ZDDP additives. ,,− It is generally accepted that these additives decompose under engine conditions, i.e., high temperatures and pressures, and that the decomposition products react to form a zinc poly(thio)phosophate film. − The exact chemical composition of the film is not known, and it is possible that a wide variety of films exist depending upon the specific conditions under which they are formed in the engine. The evolution of sulfur- and carbon-containing species such as olefins, sulfides, and mercaptans has also been observed to take place during the formation of ZDDP antiwear films, − and a number of mechanisms have been proposed to explain how the elimination of these volatile species from the system can lead to the formation of zinc poly(thio)phosphates. − ,,,,, Although none of these mechanisms have been proven to uniquely explain the formation of ZDDP antiwear films in a manner that is consistent with all of the available experimental data, the proposed mechanisms do share some common features that are potentially relevant to the formation of antiwear films.…”

Section: Introductionmentioning

confidence: 99%

A Quantum Chemical Study of the Unimolecular Decomposition Mechanisms of Zinc Dialkyldithiophosphate Antiwear Additives

Mosey

Woo

2004

J. Phys. Chem. A

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Density functional theory calculations were applied to study a set of isomerization and decomposition reactions that zinc dialkyldithiophosphate (ZDDP) engine oil antiwear additives may take part in. The products of these reactions comprise a set of chemical species that can lead to the formation of poly(thio)phosphate films that are thought to be responsible for the antiwear protection offered by ZDDPs. The specific reactions examined involved either intramolecular alkyl group transfer within ZDDP or the intramolecular elimination of olefins from this molecule. A series of substituents were employed to examine how the nature of the substituent on the ZDDP molecule affects the thermodynamic and mechanistic details of these reactions, which in turns may have ramifications regarding various aspects of antiwear film formation. It was found that qualitative and quantitative aspects of these reactions were markedly different when hydrogen atoms were used as substituents instead of alkyl groups. The details of the reactions for the H-substituted system indicated that the precursors to the antiwear films should not be formed. When alkyl groups were employed as substituents, the energetic details of the reactions considered in this study exhibited a dependence upon the nature of these groups. An examination of these details revealed that straight-chained primary alkyl ZDDPs should decompose through reactions involving alkyl group transfer, while secondary and branched primary alkyl ZDDPs should primarily undergo olefin elimination reactions to form precursors to ZDDP antiwear films. The details of the reaction pathways that these systems follow to form the precursors shed light on the observed byproducts of antiwear film formation.

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Antiwear Film Formation by ZnDTP, Detergent, and Dispersant Components of Passenger Car Motor Oils

Cited by 21 publications

References 4 publications

Soot–additive interactions in engine oils

Soot–additive interactions in engine oils

Determination of Single Particle Mass Spectral Signatures from Light-Duty Vehicle Emissions

A Quantum Chemical Study of the Unimolecular Decomposition Mechanisms of Zinc Dialkyldithiophosphate Antiwear Additives

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