Mixed lubrication of steel by C18 fatty acids revisited. Part I: Toward the formation of carboxylate

Loehlé, Sophie; Matta, C.; Minfray, Clotilde; Mogne, Th. Le; Iovine, R.; Obara, Yutaro; Miyamoto, Akira; Martin, Jean Michel

doi:10.1016/j.triboint.2014.10.020

Cited by 68 publications

(52 citation statements)

References 31 publications

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“…By comparison, the C12 and C18 coatings give μ values of 0.11 and 0.10 (Figure c). This is in agreement with previously reported studies where large reductions in μ values have been reported for phosphonates on copper, silanes on silicon, and carboxylic acids on Al 7 and steel, wherein it is believed that energy dissipation occurs through steric quenching between neighbouring alkyl chains . After acetone rinsing, the dynamic μ of C12 and C18 coatings remain the same, suggesting that sufficient chemisorbed material remains to imbue lubricity to these surfaces.…”

Section: Resultssupporting

confidence: 92%

“…In this paper, we report studies of using stearic, lauric or perfluorooctanoic acid to generate cost‐effective, low toxicity, processable films with controlled surface lubricity on low surface roughness, galvanised automotive steel. Whilst low friction, stearate films have been reported on Al 7 , steel, and mica, to our knowledge, lauric and perfluorooctanoic acid have not been studied in this context. We have linked detailed characterisation of these surfaces with coefficient of friction ( μ ) and contact angle data.…”

Section: Introductionmentioning

confidence: 88%

“…Previously, low surface energy monolayers have been used to generate low friction surfaces on different materials, e.g. stearate on Al 7 or steel, silanes on Si 10 or phosphonates on Cu 11 . In general, the organic molecules that form such monolayers contain linker groups that bind to substrate surface atoms and alkyl chains that orient away from the surface to reduce interfacial shear forces .…”

Section: Introductionmentioning

confidence: 99%

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Studies of inherent lubricity coatings for low surface roughness galvanised steel for automotive applications

Hill

Holliman

McGettrick

et al. 2017

Lubrication Science

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Surface lubricity on TiO2‐coated galvanised steels can be controlled by solution depositing perfluorooctanoic (C8), lauric (C12) or stearic (C18) acids to avoid lubricating oils/emulsions or substrate pre‐etching to remove surface oxide that add cost and waste. Water contact angles reveal increased surface hydrophobicity on coated samples that correlate with linear friction testing, suggesting water contact angle can be used to screen lubricity compounds. Linear friction testing shows that C12 and C18 lower the coefficient of friction (μ) by 50–60% compared with uncoated substrates whilst C8 drops μ from 0.31 to 0.22. Surfaces have been characterised by X‐ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy, whilst infrared confirms that as‐deposited coatings contain physisorbed and deprotonated acids chemisorbed through esters and thermal gravimetric analysis confirms increasing loadings from C8 to C12 to C18. Surface washing removes physisorbed material and lowers μ by increasing surface organisation and alkyl chain packing that enhances frictional energy dissipation through steric quenching. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Studies of inherent lubricity coatings for low surface roughness galvanised steel for automotive applications

Hill

Holliman

McGettrick

et al. 2017

Lubrication Science

View full text Add to dashboard Cite

show abstract

“…Ab initio NEMD simulations have also been performed on additive systems subjected to confinement and shear. For example, TB-QCMD has been used to investigate OFM adsorption on iron oxide surfaces under sliding conditions [296][297][298]. The main advantage of ab initio MD simulations over MD with reactive force-fields is that they do not require extensive force-field parameterisation in order to ensure accurate results.…”

Section: Linking MD To Smaller Scalesmentioning

confidence: 99%

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

2018

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Nonequilibrium molecular dynamics (NEMD) simulations have provided unique insights into the nanoscale behaviour of lubricants under shear. This review discusses the early history of NEMD and its progression from a tool to corroborate theories of the liquid state, to an instrument that can directly evaluate important fluid properties, towards a potential design tool in tribology. The key methodological advances which have allowed this evolution are also highlighted. This is followed by a summary of bulk and confined NEMD simulations of liquid lubricants and lubricant additives, as they have progressed from simple atomic fluids to ever more complex, realistic molecules. The future outlook of NEMD in tribology, including the inclusion of chemical reactivity for additives, and coupling to continuum methods for large systems, is also briefly discussed.

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“…One mechanism is that the polar functional groups of the friction modier adsorb onto the surface, much like self-assembled monolayers (SAMs), and the carbon chains form a barrier to prevent substrate-substrate adhesion thus lowering friction. 3,5,6 The other model is semiordered viscous multilayers prevent contact. 3,5,7 Free fatty acids are still used today to reduce friction, this is due to their ability to create closely packed monolayers.…”

Section: 4mentioning

confidence: 99%

Challenges and developments of self-assembled monolayers and polymer brushes as a green lubrication solution for tribological applications

et al. 2015

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ab Self-assembled monolayers (SAMs), after originally being investigated due to their functions in changing surface wettability, have been significantly developed over the years. Many types of SAMs have been developed on a variety of substrates. However their formation mechanism, rate and quality are found to be influenced by many factors. A range of SAMs including single-and multi-component are included in this review with focus on the nano and macro tribological properties. More recently, surface initiated polymer brushes, i.e. macromolecular assemblies attached to a substrate, have emerged to be an alternative and promising method for surface modification. The ability to tether these macromolecules to tribological contacts is key to their resistance to shear under loaded contacts. This review also covers atom transfer radical polymerisation (ATRP) and the role of this technique in developing new lubrication solutions. Particular care has been taken to include the development of lubrication solutions for silicon nitride due to the importance of this material as an engineering ceramic. This paper reviews the stateof-the-art development of SAMs and polymer brushes especially the potential opportunities and challenges in applying them in tribological contacts as a lubrication solution.

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Mixed lubrication of steel by C18 fatty acids revisited. Part I: Toward the formation of carboxylate

Cited by 68 publications

References 31 publications

Studies of inherent lubricity coatings for low surface roughness galvanised steel for automotive applications

Studies of inherent lubricity coatings for low surface roughness galvanised steel for automotive applications

Advances in nonequilibrium molecular dynamics simulations of lubricants and additives

Challenges and developments of self-assembled monolayers and polymer brushes as a green lubrication solution for tribological applications

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