X-Ray Absorption Study of the Effect of Calcium Sulfonate on Antiwear Film Formation Generated From Neutral and Basic ZDDPs: Part 2 — Sulfur Species

Kasrai, M.; Fuller, Marina L. Suominen; Bancroft, G.M.; Yamaguchi, E. S.; Ryason, P. R.

doi:10.1080/10402000308982661

Cited by 27 publications

(24 citation statements)

References 9 publications

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“…Over-based calcium sulfonate reduced friction and wear as already demonstrated in previous works [4][5][6][7][8][9][10][11][12] whereas the neutral one exhibited poor effects. 2.…”

Section: Discussionsupporting

confidence: 61%

“…The additives are primarily introduced as a detergent for lubricants, which are subject to scavenge any acidic substances generated during the use of lubricant. Later, they were found to exhibit anti-wear and extreme-pressure properties under boundary conditions [4][5][6][7][8][9][10][11][12]. In our previous work on working mechanism on overbased sulfonates [13], we have found that calcium oxide deposited on rubbing surface plays an important role on reduction of friction and wear.…”

Section: Introductionmentioning

confidence: 99%

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TOF-SIMS analysis of boundary films derived from calcium sulfonates

et al. 2006

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Tribological properties of over-based and neutral calcium sulfonate were examined under boundary lubrication conditions by using a ball-on-flat type tribo-tester. It was found that over-based calcium sulfonate reduced friction and wear of steel-steel contacts, whereas the neutral calcium sulfonate did not. It was found that boundary film composed of calcium oxide plays significant role on improving the tribological properties. Surface analyses by XPS and Time-of-flight secondary mass spectroscopy (TOF-SIMS) revealed that the major component of the film on upper surfaces is calcium carbonate and that at subsurfaces are composed of calcium oxide. A depth profile of the film obtained by TOF-SIMS using an etching technique revealed that thickness of the film is up to 240 nm. A static pyrolysis of the over-based calcium sulfonate on steel surface affords a thin film composed of calcium oxide, indicating that rubbing process is essential for the formation of the boundary film.

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“…Over-based calcium sulfonate reduced friction and wear as already demonstrated in previous works [4][5][6][7][8][9][10][11][12] whereas the neutral one exhibited poor effects. 2.…”

Section: Discussionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

TOF-SIMS analysis of boundary films derived from calcium sulfonates

et al. 2006

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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 XPS and XANES studies of the metal surfaces worn by a pin-on-disk tribometer using blends of ZDDP with overbased detergent it has been shown that there is competition for the surface and that the overbased detergent breaks down to form carbonate, which is deposited on the surface of the metal [15]. It was suggested that the Ca 2+ ions replaced the Zn 2+ in the polyphosphate structure of the film which significantly shortens the chain length and results in a deterioration of the anti-wear properties of the ZDDP [16][17][18][19]. Additionally, recent studies of aged engine oil using NMR and XANES has revealed that the sulfur from the overbased calcium sulfonate can be oxidized to sulfate as the oil degrades in a fired engine [20].…”

Section: Introductionmentioning

confidence: 99%

Study of surface films of overbased sulfonates and sulfurized olefins by X-Ray Absorption Near Edge Structure (XANES) spectroscopy

Costello¹,

Kasrai

2006

Tribol Lett

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The X-Ray Absorption Near Edge Structure (XANES) spectroscopy technique has been successfully applied to complex matrices such as tribological films, coal, DLC films and, where other instrumental analytical techniques are less sensitive for molecular analysis. Four-ball tests were performed for lubricating oils containing the synergistic combination of overbased sulfonate (calcium and magnesium) and sulfurized olefin. The surface films were analyzed by XANES using C K-edge, Ca L-edge and S L-and K-edge. Using this technique we were able to differentiate the carbonate from organic carbon in C K-edge spectra, as well as, determining the difference between FeS, FeS 2, RSO 3 ) and SO 4 2) in the sulfur spectra. It was found while the sulfurized olefin reacts very strongly with the substrate to form FeS, the overbased calcium sulfonate and overbased magnesium sulfonate do not react strongly with the substrate without sulfurized olefin present. There is evidence to suggest that the overbased sulfonate promotes decomposition of the sulfurized olefin on the surface to form both CaSO 4 and FeS, which improves the EP performance of the lubricant.

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X-Ray Absorption Study of the Effect of Calcium Sulfonate on Antiwear Film Formation Generated From Neutral and Basic ZDDPs: Part 2 — Sulfur Species

Cited by 27 publications

References 9 publications

TOF-SIMS analysis of boundary films derived from calcium sulfonates

TOF-SIMS analysis of boundary films derived from calcium sulfonates

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

Study of surface films of overbased sulfonates and sulfurized olefins by X-Ray Absorption Near Edge Structure (XANES) spectroscopy

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