Effects of Mo-Containing Dispersants on the Function of ZDDP: Chemistry and Tribology

Zhang, Z.; Yamaguchi, E. S.; Yu, Lei; Kasrai, M.; Bancroft, G.M.

doi:10.1080/10402000601105532

Cited by 8 publications

(5 citation statements)

References 25 publications

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“…At intervening temperatures between mild lubrication, discussed above, and EP lubrication, which likely occur, for example, in the formation of antiwear lms from zinc dialkyl dithiophosphates (ZDDP), [74][75][76][77][78][79][80][81][82][83][84][85] a common antiwear additive to engine oils, both thermal and shear effects are likely to occur simultaneously. While, in such cases, the surface conditions (particularly temperature) are less well dened, the processes will likely be a combination of the effects observed at the extrema.…”

Section: Comparison Of Shear and Thermal Effects In Tribofilm Formationmentioning

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: Comparison Of Shear and Thermal Effects In Tribofilm Formationmentioning

confidence: 99%

Shear and thermal effects in boundary film formation during sliding

et al. 2014

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“…Other than surface characterization of AW films, another ''hot'' research spot is the study on additive interactions between ZDDPs and other additives such as detergents, dispersants and molybdenum dithiophosphates (MoDTCs) [28][29][30][31][32][33]. The fundamental understanding of the reactions between the ZDDPs alone with metallic surfaces is of great importance to the binary additive systems or the formulated package.…”

Section: Introductionmentioning

confidence: 99%

Studies on ZDDP Anti-Wear Films Formed Under Different Conditions by XANES Spectroscopy, Atomic Force Microscopy and 31P NMR

Pereira

Kasrai

et al. 2007

Tribol Lett

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Antiwear (AW) films, generated from a mineral base oil containing a zinc dialkyl dithiophosphate (ZDDP) additive, were studied as a function of formation temperature, load and rubbing time. The surface morphology of these films was investigated using atomic force microscopy (AFM), and surface roughness calculated for the observed differing surface morphologies. The morphology of the films is heterogeneous for all the tested conditions, but the surface roughness is dependent on the rubbing condition. X-ray absorption near edge structure (XANES) spectroscopy has been used to characterize the chemistry of these films, and the intensity of the phosphorus K-edge was also used to monitor their thickness. The thickness of these films is in the range of 10-90 nm depending on the running conditions. Phosphorus L-edge spectra show that these films have a similar chemical nature with variable polyphosphate chain-lengths. 31P NMR was used to study the decomposition of ZDDP in the residual oils. The spectra show that the primary and secondary ZDDP react differently under the various conditions. The tribological characteristics of these AW films were probed by measuring the coefficients of friction (l) and the wear scar width (WSW) of the counter faces. l is highly related to the applied load and the results of WSW measurements show that the wear performance is related to all the tested parameters, temperature, load and rubbing time.

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“…in their study. 65 Detection of molybdenum oxides (MoO 3 ) without MoS 2 layers in the MoS 2 + base oil-derived tribofilm was the reason for the poor antiwear layers to protect the surface from the wear. Therefore, it had a poor antiwear performance with the highest wear rate against ZDDP and MoS 2 + ZnSO 4 .…”

Section: Discussionmentioning

confidence: 99%

Enhanced MoS₂antiwear performance by the presence of ZnSO₄against ZDDP

Özkan

Yaşa

2020

Proceedings of the Institution of Mechanical Engineers, Part C:

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Zinc dithiophosphate is the most commonly used antiwear additive in lubricating oil. However, zinc dithiophosphate has a poisoning effect on engine catalysis via phosphorus and zinc content that reduces the efficiency causing hazardous emission increase, therefore, it needs to be replaced with an alternative additive. In this study, the antiwear performance of molybdenum disulfide (MoS2) is enhanced by zinc sulfate (ZnSO4) addition and subjected to tribometer tests at different contact pressures to explore the MoS2 + ZnSO4friction and antiwear performance against MoS2and zinc dithiophosphate. Wear rates and surface morphology changes were carried out by an optical microscope, optical profilometer, and atomic force microscope analysis. Furthermore, tribochemical and surface energies of tribofilms were evaluated via scanning electron microscope/energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscope adhesion force mapping analysis. Results showed that ZnSO4addition to MoS2 + base oil improves the antiwear performance of the lubricating oil significantly and it presents similar friction characteristics to zinc dithiophosphate.

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Effects of Mo-Containing Dispersants on the Function of ZDDP: Chemistry and Tribology

Cited by 8 publications

References 25 publications

Shear and thermal effects in boundary film formation during sliding

Shear and thermal effects in boundary film formation during sliding

Studies on ZDDP Anti-Wear Films Formed Under Different Conditions by XANES Spectroscopy, Atomic Force Microscopy and 31P NMR

Enhanced MoS₂antiwear performance by the presence of ZnSO₄against ZDDP

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Effects of Mo-Containing Dispersants on the Function of ZDDP: Chemistry and Tribology

Cited by 8 publications

References 25 publications

Shear and thermal effects in boundary film formation during sliding

Shear and thermal effects in boundary film formation during sliding

Studies on ZDDP Anti-Wear Films Formed Under Different Conditions by XANES Spectroscopy, Atomic Force Microscopy and 31P NMR

Enhanced MoS2antiwear performance by the presence of ZnSO4against ZDDP

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Product

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Enhanced MoS₂antiwear performance by the presence of ZnSO₄against ZDDP