X-ray absorption spectroscopy of antiwear films on aluminum alloys generated from zinc dialkyldithiophosphate

Fuller, Marina L. Suominen; Kasraia, Masoud; Sheasby, J. S.; Bancroft, G.M.; Fyfe, K.; Tan, K. H.

doi:10.1007/bf00174260

Cited by 29 publications

(25 citation statements)

References 14 publications

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“…As a result, one would expect the formation and behavior of these films to be dictated by the chemical properties of the underlying substrate. The similarities between ZDDP AW films formed on a number of chemically distinct surfaces suggests otherwise [8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 96%

Interpretation of experiments on ZDDP anti-wear films through pressure-induced cross-linking

et al. 2006

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We review a recently developed molecular-level theory for the formation and functionality of zinc dialkyldithiophosphate antiwear films [N. J. Mosey, M. H. Mu¨ser and T. K. Woo, Science 307 (2005) 1612]. This theory is based on the idea that pressureinduced cross-linking leads to chemically connected networks. The formation of cross-links modifies the mechanical properties of the films such that wear inhibition may be enhanced. Furthermore, the networks remain intact upon release of the pressure, which resists flow of the film out of the contact area. The ability of the theory to account for a diverse body of experimental data related to anti-wear additives and films is discussed. Routes towards the development of new AW additives are also suggested on the basis of the theory.

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Section: Introductionmentioning

confidence: 96%

Interpretation of experiments on ZDDP anti-wear films through pressure-induced cross-linking

et al. 2006

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“…It is generally thought that the grains, after honing and etching of the surface, act like riders that bear the load of the conforming surfaces. Very little research has been performed on the lubrication of Al-Si alloys using ZDDP [36][37][38][39][40]. The findings already published contain conflicting conclusions.…”

Section: Introductionmentioning

confidence: 97%

“…In three of the four studies, the addition of the ZDDP additive to base oil had little or no effect in preventing wear. In two studies the authors used XANES [39,40] analysis to examine the wear scars for the presence of phosphorous decomposition products of ZDDP. The authors found that the ZDDP tribofilms, which form on the Al-alloys surfaces, are essentially identical to those that form on steel.…”

Section: Introductionmentioning

confidence: 99%

Spatially resolved nanoscale chemical and mechanical characterization of ZDDP antiwear films on aluminum?silicon alloys under cylinder/bore wear conditions

et al. 2005

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Understanding the lubrication of aluminum-silicon (Al-Si) alloys (>18% Si) under conditions similar to those in the cylinder/bore system is vital to determining their applicability to current engine designs. A novel investigation of the location of zinc-dialkyl-dithiophosphate (ZDDPs) antiwear (AW) film formation on an Al-Si alloy has been performed using X-ray absorption near edge structure (XANES) analysis, X-ray photoelectron emission spectroscopy (X-PEEM), and imaging nanoindentation techniques. A study of the initial stages of wear (10 min) to prolonged rubbing (60 min) was performed. The findings show that the film forms primarily on the raised silicon grains and is consistent with a zinc polyphosphate glass. The film has an elastic modulus of $70 GPa and a similar elastic response to a ZDDP AW film formed on steel under the same conditions. This provides the first direct observation and characterization of a ZDDP antiwear film on Al-Si alloys using spatially resolved chemical and mechanical techniques at the nanoscale.

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“…tribofilms, whether on iron [34], Al-Si alloys [14,35] or other coated surfaces [34]. In addition, several other studies [26,36] examined the effect of detergents and dispersants on the decomposition reactions and the synergy between the different oil additives.…”

Section: Introductionmentioning

confidence: 99%

An in situ synchrotron XAS methodology for surface analysis under high temperature, pressure, and shear

Dorgham

Neville

Ignatyev

et al. 2017

Review of Scientific Instruments

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The complex tribochemical nature of lubricated tribological contacts is inaccessible in real time without altering their initial state. To overcome this issue, a new design of a pin-on-disc tribological apparatus was developed and combined with synchrotron X-ray absorption spectroscopy (XAS). Using the designed apparatus, it is possible to study in situ the transient decomposition reactions of various oil additives on different surfaces under a wide range of realistic operating conditions of contact pressure (1.0–3.0 GPa), temperature (25–120 °C), and sliding speed (30–3000 rpm or 0.15–15 m/s). To test the apparatus, several tribological tests were performed at different shearing times ranging from 2.5 to 60 min. These tests were carried out under helium atmosphere at a temperature of 80 °C, contact pressure of 2.2 GPa, and sliding speed of 50 rpm. The XAS experiments indicate that the zinc dialkyldithiophosphate antiwear additive decomposes in the oil to form a tribofilm on the iron surface at different reaction kinetics from the ones of the thermal film. The tribofilm composition evolves much faster than the one of the thermal film, which confirms that the formation of the tribofilm is a thermally activated process similar to the one of the thermal film but accelerated by shear. Furthermore, the results indicate that the sulfur of the formed film, whether a tribofilm or a thermal film, appears initially in the form of sulfate, with some sulfide, which under heat or shear is reduced into mainly sulfide.

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X-ray absorption spectroscopy of antiwear films on aluminum alloys generated from zinc dialkyldithiophosphate

Cited by 29 publications

References 14 publications

Interpretation of experiments on ZDDP anti-wear films through pressure-induced cross-linking

Interpretation of experiments on ZDDP anti-wear films through pressure-induced cross-linking

Spatially resolved nanoscale chemical and mechanical characterization of ZDDP antiwear films on aluminum?silicon alloys under cylinder/bore wear conditions

An in situ synchrotron XAS methodology for surface analysis under high temperature, pressure, and shear

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