Growth of adsorbed additive layer for further friction reduction

Hirayama, Tomoko; Maeda, Masayuki; Sasaki, Yoshihisa; Matsuoka, Takashi; Komiya, Hiroshi; Hino, Masahiro

doi:10.1002/ls.1420

Cited by 18 publications

(23 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…OFMs reduce friction by adsorbing to metal surfaces [2][3][4]. The adsorbed layer has friction reducing properties but its properties may change during rubbing [5,6]. Rubbing may encourage multilayer formation [7], or tribochemical reaction.…”

Section: Introductionmentioning

confidence: 99%

Interactions between organic friction modifier additives

Fry

Chui

Moody

et al. 2020

Tribology International

View full text Add to dashboard Cite

The interactions of different additives in engine oils can create synergistic or antagonistic effects. This paper studies how mixing different organic friction modifier additives affects friction reducing properties of lubricants in the boundary lubrication regime. Amines of different degree of saturation were mixed with either glycerol monooleate (GMO) or oleic acid in hexadecane. The model lubricants thus formed were characterised with Fourier-transform infrared spectroscopy. Friction tests in reciprocating motion using ball-on-disc steel-steel contacts were conducted to examine the tribological performance of these lubricants. Worn surfaces were examined using X-ray photoelectron spectroscopy. Oleic acid and oleylamine, a primary amine. Were found to form a partial ionic liquid, providing synergistic friction reduction. This positive interaction reduces with increasing degree of saturation of the amine. No synergistic effect was observed between GMO and oleylamine, suggesting that GMO does not hydrolyse into a carboxylic acid within a rubbing contact in the presence of amine.

show abstract

Section: Introductionmentioning

confidence: 99%

Interactions between organic friction modifier additives

Fry

Chui

Moody

et al. 2020

Tribology International

View full text Add to dashboard Cite

show abstract

“…Then the rheological properties of the target oil were estimated by measuring the torque during rotation of the lower disk by a load cell (6), which can measure the force in the circumferential direction when the upper disk rotates. Pushing force f b was measured with a load cell (15) set between the elastic-hinge shaft attachment (14) and the air cylinder.…”

Section: Structure Around Parallel Disksmentioning

confidence: 99%

“…Recent studies have shown that oiliness additives “grow” up to several tens of nanometers under tribological conditions . Such findings are changing our conservative knowledge on additives at the solid‐liquid interface.…”

Section: Introductionmentioning

confidence: 99%

Shear property of oil film containing oiliness additive in narrow gap measured with newly‐developed parallel‐disk viscometer supported by aerostatic bearing

Hirayama

Shibata

Harada

et al. 2019

Lubrication Science

Self Cite

View full text Add to dashboard Cite

The shear force of oil film containing an oiliness additive in a narrow gap was measured with a newly developed parallel-disk viscometer supported by an aerostatic thrust bearing. To evaluate viscometer performance, the shear force of pure base oil was first measured using an oleophobic coated disk. Using the coated disk resulted in interfacial slip between the disk surface and oil, which significantly reduced the shear force compared with that when a noncoated disk was used. Next, the shear force of base oil containing an oiliness additive was measured without using the coated disk. Again it was significantly reduced, especially when the gap was less than 1 μm. The degree of reduction depended on the oiliness additive used. These results demonstrate that an oiliness additive can cause interfacial slip, resulting in friction reduction even in a hydrodynamic lubrication regime with a submicrometer gap. KEYWORDSinterfacial slip, narrow gap, oiliness additive, parallel-disk viscometer, shear property, thin oil film | INTRODUCTIONWith the strong demand for energy-conserving machines, usage of ultralow viscosity oil is rapidly becoming more common especially as engine oil for automobiles. The formed oil film is then thinner than that when high viscosity oil is used, reaching boundary lubricated state more easily. Then the additives mixed into the base oil have come to play a key role in achieving lower friction coefficients and higher wear durability for sliding surfaces. Particularly, oiliness additives generally form an adsorption layer on metal surfaces and thereby reduce friction, especially under lower pressure conditions in the boundary lubrication regime.Nomenclature: a, contact radius; c r0 , gap between the flat face of the outer ring area on the upper specimen and the lower disk; f 0 , shear force converted from f rot ; f b , pushing force by the air cylinder; f s , axial force generated in the aerostatic bearing; f rot , circumferential force measured by the load cell (6); h eq , equivalent gap in area 2 of the aerostatic bearing; h l , gap in area 3 of the aerostatic bearing; l, distance from the rotation centre to the pushing point of the load cell (6); p a , atmospheric pressure; p g , pressure at r g of the aerostatic bearing; p i (i=2,3), pressure in areas 2 and 3 of the aerostatic bearing; p s , inlet pressure for the aerostatic bearing; p ′ s , pressure at r s of the aerostatic bearing; r 0 , inner radius of the outer ring area on the upper specimen; r 1 , outer radius of the outer ring area on the upper specimen; r a , outer radius of area 3 of the aerostatic bearing; r g , outer radius of area 2 of the aerostatic bearing; r s , outer radius of inlet port of the aerostatic bearing; C, airflow contraction coefficient; E′, equivalent Young modulus; P max , maximum Hertz pressure; R, gas constant; T, temperature; δ, groove depth; γ, circumferential area ratio of the grooves; η, sample oil viscosity; η ap , apparent viscosity calculated from the measured shear force; κ, heat capacity ratio; μ, air visco...

show abstract

“…Hirayama et al use Ar gas introduced into a liquid reservoir to control the pressure of a lubricant additive mixture against a Cu surface. [20] This is a similar approach to work of Koga et al looking at swelling of polymers using supercritical CO 2 , (section 2.3.3 above). [81,82] One limitation of this approach is the purity and solubility of the gas used.…”

Section: Extreme Conditionsmentioning

confidence: 85%

“…[13] An alternative approach to study surfaces which are not transparent to neutrons, is to support a thin film of the material on a transparent substrate. This has been reported for an increasing number of metal systems including Fe [14,15], Ti [16][17][18], Cu [19][20][21][22][23][24][25], Ni [26][27][28], Al [29,30] and Au [31][32][33][34]. Steel [35] remains a challenge with the overall deposited composition replicated, but the metallurgical aspects are not necessarily typical of bulk steel (see section 2.3 below).…”

Section: Solid Substratesmentioning

confidence: 94%

New insights into the solid–liquid interface exploiting neutron reflectivity

Welbourn¹,

Clarke

2019

Current Opinion in Colloid & Interface Science

View full text Add to dashboard Cite

We outline recent progress exploiting neutron reflectivity for structural and compositional investigations of the solid-liquid interface. There has been extensive activity in this area, with key areas of development: (i) an increased range of accessible substrates (e.g. metals and minerals), (ii) novel liquid phases, and (iii) strong themes in electrochemistry (e.g. batteries), corrosion, polymers and increasing application of extreme conditions.

show abstract

Growth of adsorbed additive layer for further friction reduction

Cited by 18 publications

References 33 publications

Interactions between organic friction modifier additives

Interactions between organic friction modifier additives

Shear property of oil film containing oiliness additive in narrow gap measured with newly‐developed parallel‐disk viscometer supported by aerostatic bearing

New insights into the solid–liquid interface exploiting neutron reflectivity

Contact Info

Product

Resources

About