Low‐ and zero‐sulphated ash, phosphorus and sulphur anti‐wear additives for engine oils

Spikes, H. A.

doi:10.1002/ls.57

Cited by 232 publications

(137 citation statements)

References 149 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: 75%

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: 75%

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

Ofune

Banks

Morina

et al. 2016

Tribology International

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“…In order to control pollution, European and American countries have enacted stringent new emission standards that require an extended life for exhaust systems, improved fuel efficiency, and the use of less toxic biodegradable lubricants with acceptable environmental compatibility. The new specified limits of sulfated ash, phosphorous, and sulfur in lubricants are lower than previously defined ones [1]. These limits now require adjusting and improving engine oil formulations, the gradual introduction of ash-less antioxidants, anti-wear additives, and enhancements in dispersant and viscosity indices.…”

Section: Introductionmentioning

confidence: 88%

Isosteric design of friction-reduction and anti-wear lubricant additives with less sulfur content

et al. 2017

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Abstract:To reduce harmful sulfur content in lubricant additives, making use of isosterism has been shown to be an effective strategy. When thiobenzothiazole compounds were used as templates, the exchange of sulfur atoms in the thiazole ring with oxygen atoms and NH groups produced twelve isosteres. Similarly, 2-benzothiazole-S-carboxylic acid esters were used as template molecules to produce six isosteres. About 30% of the isosteres exhibited a satisfactory deviation of ±5% relative to the template, ignoring the specific changes in the base oils, the differences in molecular structure, and the friction or wear properties. The template molecules and isosteres in triisodecyl trimellitate exhibited better tribological properties than in trimethylolpropane trioleate or bis(2-ethylhexyl) adipate. Comparative molecular field analysis (CoMFA)-and comparative molecular similarity index analysis (CoMSIA)-quantitative structure tribo-ability relationship (QSTR) models were employed to study the correlation of molecular structures between the base oils and additives. The models indicate that the higher the structural similarities of the base oils and additives are, the more synergetic the molecular force fields of the lubricating system are; the molecular force fields creating synergistic effects will improve tribological performance.

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“…2 An alternative approach to replacing ZDDP by other anti-wear additives is to remove the need for an anti-wear additive in the fi rst place, and one possible way to do this is to coat the surfaces of rubbing engine components with highly wear-resistant materials. One very promising material is diamond-like carbon (DLC), and the third paper describes work on a particular type of DLC coating and its very effective interaction with the unusual friction-reducing agent, glycerol.…”

Section: Beyond Zddpmentioning

confidence: 99%

Beyond ZDDP

Spikes¹

2008

Lubrication Science

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Editorial Beyond ZDDPThe lubricant additive zinc dialkyl dithiophosphate (ZDDP) has been used as an anti-wear additive in almost all engine oils for over 60 years. It has thus outlived all of the lubricant chemists and engineers who were active when it was born. It is an extraordinary additive, cheap to produce, very effective and multifunctional -especially in its combination of anti-wear and extreme pressure properties. ZDDP has stimulated an enormous amount of research, and yet many of the details of how it forms a boundary lubricating fi lm remain obscure.During the last 15 years, the future of ZDDP has become very uncertain. Engine exhaust aftertreatment devices are harmed by the presence of sulphur and phosphorus oxides and metal salts in engine exhausts, and ZDDP contains all three of these noxious species. There is thus a strong interest in fi nding additive replacements for ZDDP in its multifarious roles. In terms of ZDDP's anti-wear behaviour, this has proved remarkably diffi cult, although now, some real progress is being made. It now appears that it will be possible, if required, to develop high-performance engine oils without any ZDDP content. It is far less certain, however, whether ZDDP replacements will be wholly free of sulphur, phosphorus and metals.One thing that the possible imminent demise of ZDDP has certainly achieved is a great deal of research, into ZDDP itself, its possible replacements and how to measure the effectiveness of novel low-or zero-ZDDP formulations.This special issue contains fi ve papers that span the gamut of current research on ZDDP replacement. Three originate from primarily academia, while two are from industry. The fi rst paper is an experimental study of fi lm formation by two sulphur-and phosphorus-containing, but metal-free, additives that are suggested as possible replacements for ZDDP.1 The second explains how ZDDP adversely affects after-treatment devices, and then reviews all of the various anti-wear chemistries that might be considered as possible replacements for ZDDP. 2 An alternative approach to replacing ZDDP by other anti-wear additives is to remove the need for an anti-wear additive in the fi rst place, and one possible way to do this is to coat the surfaces of rubbing engine components with highly wear-resistant materials. One very promising material is diamond-like carbon (DLC), and the third paper describes work on a particular type of DLC coating and its very effective interaction with the unusual friction-reducing agent, glycerol. The last two papers address the practical development of ZDDP-free engine oils. One, from a lubricant additive company, describes the impact of partial or full replacement of ZDDP by a metalfree phosphorus-containing additive on friction and wear in bench tests and also on fuel economy and catalyst performance in engine tests. 4 Of particular interest is the fi nding that a non-ZDDP anti-wear additive is less harmful to exhaust catalysts than ZDDP despite it containing as much or even more LUBRICATION SCIENCE

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Low‐ and zero‐sulphated ash, phosphorus and sulphur anti‐wear additives for engine oils

Cited by 232 publications

References 149 publications

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

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

Isosteric design of friction-reduction and anti-wear lubricant additives with less sulfur content

Beyond ZDDP

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