A Model for the Boundary Film Formation and Tribological Behavior of a Phosphazene Lubricant on Steel

Choa, Sung-H.; Ludema, Kenneth C.; Potter, Gregg E.; DeKoven, Benjamin M.; Morgan, Ted; Kar, Kishore K.

doi:10.1080/10402009508983469

Cited by 28 publications

(15 citation statements)

References 18 publications

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“…Similar findings with engine oil on metal surfaces have been reported to contain films composed of low concentrations of Zn, P, S with Ca and O as the topmost layer of the tribofilm [15]. These species have been reported to affect the antiwear properties of tribofilms [22,23]. Uy et al [24] also investigated the tribofilms formed on tappets with Raman and observed Ca/Zn orthophosphate (Zn 3 (PO4) 2 ), CaCO 3 , Fe 3 O 4 with some undecomposed hydrocarbon on the surface.…”

Section: Introductionsupporting

confidence: 71%

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Development of valve train rig for assessment of cam/follower tribochemistry

Ofune

Banks

Morina

et al. 2016

Tribology International

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Component bench tests are a crucial part of a tribology assessment experimental programme for most engines and subsystems. This is because they test the components under conditions simulating the operating characteristics of the system. These have become very important as they shed more light into the friction, wear, lubrication and importantly for this study, the tribochemistry of valve train systems. This work outlines the procedure for the development of a single cam rig (SCR) from a 1.25L FORD Zetec (SE) engine. Friction plots were used to validate the data obtained from the newly developed single cam rig with Mn-phosphate coated and polished follower against a cast iron camshaft. The tribofilm formed using normal and mid Sulphated Ash, Phosphorus and Sulphur (SAPS) 5W-30 oils were evaluated and correlated to the friction and wear properties of the tribopair.Raman and FIB-SEM/EDX investigations of the tribochemical films showed that the normal SAPS oil produced patchy, thick (80-100 nm) and well dispersed tribofilm with better wear prevention capabilities. It was observed that Mid SAPS oil had lower wear prevention due to loosely dispersed and thin tribofilms. Absence of tribofilms at the centre of the insert with this oil also suggests that formation and removal processes are an integral part of the wear mechanisms in highly loaded cam follower systems.

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Section: Introductionsupporting

confidence: 71%

“…The low levels of Zn, P, and S of the tribofilm on the wear track at points 1,2, 3, and 4 clearly reduces the antiwear properties on the inserts [23]. This could be as a result of the dispersant used in the oil.…”

Section: Scanning Electron Microscopy/energy Dispersive X-rays (Sem/edx)mentioning

confidence: 99%

Development of valve train rig for assessment of cam/follower tribochemistry

Ofune

Banks

Morina

et al. 2016

Tribology International

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“…It has been stated that the tribological properties of iron fluorides are better than those of naked metal surfaces [30,31]. Despite the fact that the iron fluorides possess physical properties that are conducive to better tribological properties, they have certain disadvantages from a chemical perspective.…”

Section: Lubrication Mechanismmentioning

confidence: 99%

Tribo-Chemistry of Phosphonium-Derived Ionic Liquids

et al. 2010

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The tribological properties of room temperature ionic liquids containing tetraalkylphosphonium cations were evaluated on the basis of the chemical structure of their salts. The tribochemistry of these ionic liquids was discussed on the basis of the results of tribo-tests and surface analyses. The tribological properties of the tetraalkylphosphonium salts examined in this work were observed to be better than those of 1,3-alkylimidazolium salts. The structure of the alkyl group in the phosphonium cation also has a slight effect on the tribological properties of the salts. During a friction test carried out under lowload conditions, the phosphonium cation was oxidized to phosphate to form a boundary film. This film inhibited the reaction of the bis(trifluoromethanesulfonyl)amide anion that yielded metal fluoride on the rubbed surfaces. The combination of the phosphonium cation with a phosphate anion or thiophosphate anion resulted in a better lubricant than 1,3-alkylimidazolium bis(trifluoromethanesulfonyl)amide. The reactions of the phosphate anion and thiophosphate anion yielded a phosphate boundary film that exhibited better tribological properties than those of the fluoride boundary film.

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“…Techniques such as X-ray Photoelectron Spectroscopy (XPS) [2][3][4][5][6][7][8][9], Auger Electron Spectroscopy (AES) [3,[6][7][8][9][10][11] and Secondary Ion Mass Spectrometry (SIMS) [12,13] in conjunction with ion etching, have been used to determine the physical film thickness. Surface profilometry [9] may be used to measure the depth of the etched crater.…”

Section: Introductionmentioning

confidence: 99%

Tribofilms generated from ZDDP and DDP on steel surfaces: Part 1, growth, wear and morphology

et al. 2005

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The growth and morphology of tribofilms, generated from zinc dialkyldithiophosphate (ZDDP) and an ashless dialkyldithiophosphate (DDP) over a wide range of rubbing times (10 s to 10 h) and concentrations (0.1-5 wt% ZDDP), have been examined using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES) spectroscopy at the O, P and S K-edges and the P, S, and Fe L-edges. The physical aspects of the growth and morphology of the tribofilms will be presented in Part I and the chemistry of the films will be discussed in Part II. The major components of all films on 52100 steel are Zn and Fe phosphates and polyphosphates. The average thickness of these phosphate films has been measured using P K-edge XANES and XPS profiling. For ZDDP, a very significant phosphate film (about 100 Å thick) forms after 10 s, while film development for DDP is substantially slower. However, for both additives, the average film thickness increases to 600-800 Å after 30 min of rubbing, before leveling off or decreasing. The antiwear properties of pure ZDDP and in combination with DDP at different rubbing times and concentrations have also been examined. It was found that under all conditions, the performance of ZDDP as an antiwear agent is superior to that of DDP. However, DDP has no adverse effect on the performance of ZDDP when the two are mixed. The AFM results show that ZDDP forms larger and better developed ''pads'' than DDP at short rubbing times. At longer rubbing times, both films become more uniform. For the 1 h ZDDP films, the film thickness is surprisingly independent of the ZDDP concentration from 0.1 to 5 wt% ZDDP. The film thickness is also independent of the ratio of ZDDP/DDP concentrations.

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A Model for the Boundary Film Formation and Tribological Behavior of a Phosphazene Lubricant on Steel

Cited by 28 publications

References 18 publications

Development of valve train rig for assessment of cam/follower tribochemistry

Development of valve train rig for assessment of cam/follower tribochemistry

Tribo-Chemistry of Phosphonium-Derived Ionic Liquids

Tribofilms generated from ZDDP and DDP on steel surfaces: Part 1, growth, wear and morphology

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