Journal Home > Volume 9 , Issue 6

In this study we present a mechanism for the elastohydrodynamic (EHD) friction reduction in steel/steel contacts, which occurs due to the formation of oleophobic surface boundary layers from common boundary-lubrication additives. Several simple organic additives (amine, alcohol, amide, and fatty acid) with different molecular structures were employed as the model additives. It was found that the stronger chemisorption at 100 ℃, rather than the physisorption at 25 ℃, is more effective in friction reduction, which reaches 22%. What is more, EHD friction reduction was obtained in steel/steel contacts without use of the diamond-like carbon (DLC) coatings with their wetting or thermal effect, which was previously suggested as possible EHD friction reduction mechanism; yet about the same friction reduction of about 20% was obtained here—but with much simpler and less expensive technology, namely with the adsorbed oleophobic surface layers. A small variation in the additive’s molecular structure results in significant changes to the friction, indicating good potential in future EHD lubrication technology, where these additives could be designed and well optimised for notable reduction of the friction losses in the EHD regime.


menu
Abstract
Full text
Outline
About this article

New strategy for reducing the EHL friction in steel contacts using additive-formed oleophobic boundary films

Show Author's information Mitjan KALIN( )Maja KUS
Laboratory for Tribology and Interface Nanotechnology, Faculty of Mechanical Engineering, University of Ljubljana, Bogišićeva 8, 1000 Ljubljana, Slovenia

Abstract

In this study we present a mechanism for the elastohydrodynamic (EHD) friction reduction in steel/steel contacts, which occurs due to the formation of oleophobic surface boundary layers from common boundary-lubrication additives. Several simple organic additives (amine, alcohol, amide, and fatty acid) with different molecular structures were employed as the model additives. It was found that the stronger chemisorption at 100 ℃, rather than the physisorption at 25 ℃, is more effective in friction reduction, which reaches 22%. What is more, EHD friction reduction was obtained in steel/steel contacts without use of the diamond-like carbon (DLC) coatings with their wetting or thermal effect, which was previously suggested as possible EHD friction reduction mechanism; yet about the same friction reduction of about 20% was obtained here—but with much simpler and less expensive technology, namely with the adsorbed oleophobic surface layers. A small variation in the additive’s molecular structure results in significant changes to the friction, indicating good potential in future EHD lubrication technology, where these additives could be designed and well optimised for notable reduction of the friction losses in the EHD regime.

Keywords: friction, additives, elastohydrodynamic (EHD), oleophobic layer, boundary slip

References(61)

[1]
Stachowiak G W, Batchelor A W. Engineering Tribology. 3rd edn. Oxford (UK): Elsevier Inc., 2005.
[2]
Reynolds O. IV. On the theory of lubrication and its application to Mr. Beauchamp Tower’s experiments, including an experimental determination of the viscosity of olive oil. Philos Trans Roy Soc Lond 177: 157–234(1886)
[3]
Grubin A N. Fundamentals of the hydrodynamic theory of lubrication of heavily loaded cylindrical surfaces. In Proceedings of the Symposium on Investigation of the Contact of Machine Components, Moscow, 1949: 115-166.
[4]
Björling M, Habchi W, Bair S, Larsson R, Marklund P. Friction reduction in elastohydrodynamic contacts by thin-layer thermal insulation. Tribol Lett 53(2): 477–486(2014)
[5]
Evans R D, Cogdell J D, Richter G A, Doll G L. Traction of lubricated rolling contacts between thin-film coatings and steel. Tribol Trans 52(1): 106–113(2008)
[6]
Kalin M, Polajnar M. The effect of wetting and surface energy on the friction and slip in oil-lubricated contacts. Tribol Lett 52(2): 185–194(2013)
[7]
Polajnar M, Kalin M. Effect of the slide-to-roll ratio and the contact kinematics on the elastohydrodynamic friction in diamond-like-carbon contacts with different wetting behaviours. Tribol Lett 60(1): 8 (2015)
[8]
Choo J H, Spikes H A, Ratoi M, Glovnea R, Forrest A. Friction reduction in low-load hydrodynamic lubrication with a hydrophobic surface. Tribol Int 40(2): 154–159(2007)
[9]
Guo F, Yang S Y, Ma C, Wong P L. Experimental study on lubrication film thickness under different interface wettabilities. Tribol Lett 54(1): 81–88(2014)
[10]
Kalin M, Polajnar M. The correlation between the surface energy, the contact angle and the spreading parameter, and their relevance for the wetting behaviour of DLC with lubricating oils. Tribol Int 66: 225–233(2013)
[11]
Kalin M, Polajnar M. The wetting of steel, DLC coatings, ceramics and polymers with oils and water: The importance and correlations of surface energy, surface tension, contact angle and spreading. Appl Surf Sci 293: 97–108(2014)
[12]
Hild W, Opitz A, Schaefer J A, Scherge M. The effect of wetting on the microhydrodynamics of surfaces lubricated with water and oil. Wear 254(9): 871–875(2003)
[13]
Choi C H, Ulmanella U, Kim J, Ho C M, Kim C J. Effective slip and friction reduction in nanograted superhydrophobic microchannels. Phys Fluids 18(8): 087105 (2006)
[14]
Zhu Y, Granick S. Rate-dependent slip of Newtonian liquid at smooth surfaces. Phys Rev Lett 87(9): 096105 (2001)
[15]
Mate C M. Tribology on the Small Scale. Oxford (UK): Oxford Univ. Press, 2008.
[16]
Vinogradova O I. Slippage of water over hydrophobic surfaces. Int J Miner Process 56(1–4): 31–60(1999)
[17]
Vinogradova O I. Drainage of a thin liquid film confined between hydrophobic surfaces. Langmuir 11(6): 2213–2220(1995)
[18]
Spikes H, Granick S. Equation for slip of simple liquids at smooth solid surfaces. Langmuir 19(12): 5065–5071(2003)
[19]
Jahanmir S, Hunsberger A Z, Heshmat H. Load capacity and durability of H-DLC coated hydrodynamic thrust bearings. J Tribol 133(3): 031301 (2011)
[20]
Guo L, Wong P L, Guo F. Correlation of contact angle hysteresis and hydrodynamic lubrication. Tribol Lett 58(3): 45 (2015)
[21]
Kus M, Kalin M. Influence of additives and their molecular structure on the static and dynamic wetting of oil on steel at room temperature. Appl Surf Sci 490: 420–429(2019)
[22]
Kus M, Kalin M. Additive chemical structure and its effect on the wetting behaviour of oil at 100 ℃. Appl Surf Sci 506: 145020 (2020)
[23]
Mortier R M, Fox M F, Orszulik S T. Chemistry and Technology of Lubricants. 3rd edn. New York (USA): Springer, 2010.
[24]
Friction Modifier System, Unique Patented Friction Reducing Technology, A. Chemicals, Catalogue 2011.
[25]
Leading the way in naturally derived ingredients, Organic Friction Modifiers., Additives C L, Catalogue 2009.
[26]
Spikes H. Friction modifier additives. Tribol Lett 60: 5 (2015)
[27]
Mohrig J R, Hammond C R, Morrill T C. Experimental Organic Chemistry. New York (USA): Freeman, 1998.
[28]
Bowden F P, Tabor D. The Friction and Lubrication of Solids, Part I. Oxford (UK): Clarendon Press, 1950.
[29]
Jahanmir S, Beltzer M. An adsorption model for friction in boundary lubrication. ASLE Trans 29(3): 423–430(1986)
[30]
Dunuwila D D, Berglund K A. ATR FTIR spectroscopy for in situ measurement of supersaturation. J Cryst Growth 179(1–2): 185–193(1997)
[31]
Groen H, Roberts K J. Nucleation, growth, and pseudo-polymorphic behavior of citric acid as monitored in situ by attenuated total reflection Fourier transform infrared spectroscopy. The J Phys Chem B 105(43): 10723–10730(2001)
[32]
Lewiner F, Klein J P, Puel F, Févotte G. On-line ATR FTIR measurement of supersaturation during solution crystallization processes. Calibration and applications on three solute/solvent systems. Chem Eng Sci 56(6): 2069–2084(2001)
[33]
Feng L L, Berglund K A. ATR-FTIR for determining optimal cooling curves for batch crystallization of succinic acid. Cryst Growth Des 2(5): 449–452(2002)
[34]
Bakhbakhi Y, Charpentier P, Rohani S. The solubility of phenanthrene in toluene: In-situ ATR-FTIR, experimental measurement, and thermodynamic modelling. Can J Chem Eng 83(2): 267–273(2005)
[35]
Hamrock B J, Dowson D. Isothermal elastohydrodynamic lubrication of point contacts: Part III—Fully flooded results. J Lubr Technol 99(2): 264–275(1977)
[36]
Lafountain A R, Johnston G J, Spikes H A. The elastohydrodynamic traction of synthetic base oil blends. Tribol Trans 44(4): 648–656(2001)
[37]
Rizvi S Q A. A Comprehensive Review of Lubricant Chemistry, Technology, Selection and Design. ASTM stock number: MNL59, West Conshohocken: ASTM, 2009.
[38]
Socrates G. Infrared and Raman Characteristic Group Frequencies: Tables and Charts. New York (USA): Wiley, 2004.
[39]
Rossi A, Eglin M, Piras F M, Matsumoto K, Spencer N D. Surface analytical studies of surface-additive interactions, by means of in situ and combinatorial approaches. Wear 256(6): 578–584(2004)
[40]
Piras F M, Rossi A, Spencer N D. Growth of tribological films:  In situ characterization based on attenuated total reflection infrared spectroscopy. Langmuir 18(17): 6606–6613(2002)
[41]
Castro W, Perez J M, Erhan S Z, Caputo F. A study of the oxidation and wear properties of vegetable oils: Soybean oil without additives. J Am Oil Chem Soc 83(1): 47–52(2006)
[42]
Kumar S, Mishra N M, Mukherjee P S. Additives depletion and engine oil condition—a case study. Ind Lubr Tribol 57(2): 69–72(2005)
[43]
Duddeck H. E. E. Pretsch, P. Bühlmann, C. Affolter. Structure determination of organic compounds—Tables of spectra data. Springer, Berlin, 2000. 421 pp. plus CD-ROM. Price £ 40.39, DM 79.00. ISBN 3 540 67815 8. Magn Reson Chem 40(3): 247–247(2002)
[44]
Gosvami N N, Bares J A, Mangolini F, Konicek A R, Yablon D G, Carpick R W. Mechanisms of antiwear tribofilm growth revealed in situ by single-asperity sliding contacts. Science 348(6230): 102–106(2015)
[45]
Adams H L, Garvey M T, Ramasamy U S, Ye Z J, Martini A, Tysoe W T. Shear-induced mechanochemistry: Pushing molecules around. J Phys Chem C 119(13): 7115–7123(2015)
[46]
Adams H, Miller B P, Kotvis P V, Furlong O J, Martini A, Tysoe W T. In situ measurements of boundary film formation pathways and kinetics: Dimethyl and diethyl disulfide on copper. Tribol Lett 62: 12 (2016)
[47]
Felts J R, Oyer A J, Hernández S C, Whitener K E Jr, Robinson J T, Walton S G, Sheehan P E. Direct mechanochemical cleavage of functional groups from graphene. Nat Commun 6: 6467 (2015)
[48]
Yeon J, He X, Martini A, Kim S H. Mechanochemistry at solid surfaces: Polymerization of adsorbed molecules by mechanical shear at tribological interfaces. ACS Appl Mater Interfaces 9(3): 3142–3148(2017)
[49]
He X, Kim S H. Mechanochemistry of physisorbed molecules at tribological interfaces: Molecular structure dependence of tribochemical polymerization. Langmuir 33(11): 2717–2724(2017)
[50]
Spikes H A. Slip at the wall—evidence and tribological implications. Tribol Ser 41: 525–535(2003)
[51]
Choo J H, Forrest A K, Spikes H A. Influence of organic friction modifier on liquid slip: A new mechanism of organic friction modifier action. Tribol Lett 27(2): 239–244(2007)
[52]
Hare E F, Zisman W A. Autophobic liquids and the properties of their adsorbed films. J Phys Chem 59(4): 335–340(1955)
[53]
Bigelow W C, Pickett D L, Zisman W A. Oleophobic monolayers: I. Films adsorbed from solution in non-polar liquids. J Colloid Sci 1(6): 513–538(1946)
[54]
Tamam L, Ocko B M, Deutsch M. Two-dimensional order in mercury-supported langmuir films of fatty diacids. Langmuir 28(44): 15586–15597(2012)
[55]
Jahanmir S. Chain length effects in boundary lubrication. Wear 102(4): 331–349(1985)
[56]
Torbacke M, Rudolphi Å K, Kassfeldt E. Lubricants: Introduction to Properties and Performance. Chichester (UK): Wiley, 2014.
[57]
Spikes H A. Film-forming additives-direct and indirect ways to reduce friction. Lubr Sci 14(2): 147–167(2002)
[58]
Okabe H, Masuko M, Sakurai K. Dynamic behavior of surface-adsorbed molecules under boundary lubrication. ASLE Trans 24(4): 467–473(1981)
[59]
Jahanmir S, Beltzer M. Effect of additive molecular structure on friction coefficient and adsorption. J Tribol 108(1): 109–116(1986)
[60]
Studt P. The influence of the structure of isomeric octadecanols on their adsorption from solution on iron and their lubricating properties. Wear 70(3): 329–334(1981)
[61]
Doig M, Warrens C P, Camp P J. Structure and friction of stearic acid and oleic acid films adsorbed on iron oxide surfaces in squalane. Langmuir 30(1): 186–195(2014)
Publication history
Copyright
Acknowledgements
Rights and permissions

Publication history

Received: 06 April 2020
Accepted: 15 May 2020
Published: 26 September 2020
Issue date: December 2021

Copyright

© The author(s) 2020

Acknowledgements

The authors acknowledge the financial support from the Slovenian Research Agency (Research Core Funding No. P2-0231).

Rights and permissions

This article is licensed under a Creative Commons Attribution 4.0 International Li-cense, which permits use, sharing, adaptation, distribution and reproduction in any medium or for-mat, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.

The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not in-cluded in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Return