Reduced Phosphorus Concentration Effects on Tribological Performance of Passenger Car Engine Oils

Gao, Hong; McQueen, J. Scott; Black, E. D.; Gangopadhyay, Arup; Jensen, R. K.

doi:10.1080/05698190490431885

Cited by 24 publications

(7 citation statements)

References 12 publications

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“…However, there is a slight increase in friction when the anti-wear additive level is high as seen between Oil2 and Oil3. Such kind of behaviour has been reported by other researchers for steel tribo-pair at temperatures above 80°C [21] and this increase in friction as level of anti-wear additive increases could be associated with the changes in the mechanical properties of the contact surface due to tribofilm formation. The Al-Sn based lining lubricated with pure PAO base oil shows less wear compared to that Table 5 Test parameters used for friction and wear test lubricated with oils containing additives.…”

Section: Al-sn Based Lining Without Overlay (A1)supporting

confidence: 77%

Tribological Compatibility of Some Selected Pb-Free Engine Bearing Materials with Different Engine Oil Formulations

et al. 2018

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In this study, friction and wear properties of Al-Sn based bearing alloy with no overlay, bronze lining coated with Al-Sn based overlay and PAI based overlay, bronze lining coated with Sn based overlay and Pb-containing bearing material have been investigated using five different engine oil formulations including pure PAO 6 base oil and different viscosity grade oils containing anti-wear additive using an Optimol SRV® high-temperature reciprocating friction and wear test machine. It has been found that when Al-Sn based lining is lubricated with plain base oil, wear is lower compared to those with oils containing additives. For the other bearing materials, oils containing additives have shown improved friction and wear performance compared with that of the pure base oil.

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Section: Al-sn Based Lining Without Overlay (A1)supporting

confidence: 77%

Tribological Compatibility of Some Selected Pb-Free Engine Bearing Materials with Different Engine Oil Formulations

et al. 2018

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“…The friction trace as a function of time ( figure 7(a)) has been shown to correlate well with the build up of ZDDP tribofilm with rubbing measured indirectly using ECR [57] and SLIM [60] techniques. Results obtained with the SLIM technique [60], figure 7(b), illustrate that the ZDDP tribofilm starts to form during the initial rubbing, it reaches maximum film thickness after 1 h of rubbing and then the film thickness levels out to a steady state.…”

Section: Zddp Film Formation/replenishmentmentioning

confidence: 76%

Tribofilms: aspects of formation, stability and removal

Morina¹,

Neville²

2007

J. Phys. D: Appl. Phys.

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There has been much attention paid to the lubricant additives zinc dialkyldithiphosphate and molybdenum dialkyldithiocarbamate as the most commonly used antiwear/antioxidant and friction modifiers. The mechanism by which they function has been the subject of much research work. As a result of these efforts the tribofilms formed from the above additives are fully chemically characterized but understanding the physical properties and the dynamics of their formation, stability and removal is still not satisfactory and needs more research. This paper reviews the general characteristics of tribofilms formed from these additives in single component systems and also on their interactions as well as the current understanding of the dynamics of their formation. Experimental work is then presented alongside discussion of the literature to present a current status of understanding of the stability and the removal of tribofilms. The effect of temperature and additive interactions on the thickness of the steady state tribofilms, and consequently the effect on friction performance, is evaluated. The results of this study show that temperature and additive interactions play a significant role on the dynamic process of tribofilm formation as well as its chemical properties. This study also highlights the areas in which further development is needed to ensure progress in understanding of the tribofilm's formation and removal processes.

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“…Georges et al [5] studied the induction period prior to ZDDP forming an insulating reaction film and observed the temperature-dependent formation of a ''thick'' film in a steel-on-steel rubbing contact. ECR has been used by many other authors to monitor the generation of insulating film between rubbed surfaces with broadly similar findings [6][7][8][9][10]. Until recently this was the only method that could continually monitor film thickness within the rubbing contact while rubbing itself is taking place, but unfortunately this technique does not provide a reliable measure of actual film thickness as there is no direct relationship between contact resistance and film thickness.…”

Section: Introductionmentioning

confidence: 96%

Film thickness and roughness of ZDDP antiwear films

2007

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The two experimental techniques, spacer layer interferometry imaging (SLIM) and atomic force microscopy (AFM), have been used to measure the thickness and roughness of zinc dialkyl dithiophosphate (ZDDP) reaction films formed in a rolling-sliding minitraction machine (MTM) tribometer. The AFM method has been complemented by a novel ZDDP film removal method based on ethylenediaminetetraacetic acid (EDTA) solution. It has been found that the two approaches measure very similar ZDDP film thickness values, lending credence to both methods. However the AFM approach measures much rougher ZDDP reaction films than MTM-SLIM and it is believed that SLIM underestimates the film roughness. Based on this, the use of MTM-SLIM is recommended for monitoring the evolution of antiwear film thickness during rubbing, while AFM should be employed for studying the morphology of antiwear films.There has been a great deal of research to characterize the reaction films formed by the antiwear additive zinc dialkyl dithiophosphate (ZDDP). Particular attention has focused on the thickness of ZDDP films since it is known that thick ZDDP surface films enhance mixed lubrication friction [1] and influence wear [2].In practice, ZDDP film thickness is difficult to quantify precisely since ZDDP forms patchy, uneven reaction films. It is thus important to represent film thickness by more than a single value: the maximum and mean film thickness, the kinetics of the film thickness, the root mean square roughness and average slope are all likely to be important.Measurements of the thickness of antiwear films formed by ZDDP solutions on rubbing surfaces published over more than the last 50 years agree surprisingly well, despite the fact that the ZDDP films studied were formed in different rubbing experiments and that various film thickness characterization methods were employed.Soon after ZDDPs were introduced as lubricant additives it was recognized that they form relatively thick films on rubbed surfaces compared to most other lubricant additives. In the 1950s, 32 P radiotracing was used to show that ZDDP solutions rapidly formed films on rubbed cast iron surfaces that stabilized at approximately 120 nm thickness [3]. Using X-ray fluorescence (XRF) Rounds [4] found that films formed by ZDDP on rubbed surfaces were Ôseveral hundred monolayers thickÕ.

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Reduced Phosphorus Concentration Effects on Tribological Performance of Passenger Car Engine Oils

Cited by 24 publications

References 12 publications

Tribological Compatibility of Some Selected Pb-Free Engine Bearing Materials with Different Engine Oil Formulations

Tribological Compatibility of Some Selected Pb-Free Engine Bearing Materials with Different Engine Oil Formulations

Tribofilms: aspects of formation, stability and removal

Film thickness and roughness of ZDDP antiwear films

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