Adsorbed film structure and tribological performance of aqueous copolymer lubricants with phosphate ester additive on Ti coated surface

Lin, Bingjing; Zhu, Hong Tao; Hirayama, Tomoko; Kosasih, Buyung; Novareza, Oyong

doi:10.1016/j.wear.2015.01.042

Cited by 15 publications

(51 citation statements)

References 51 publications

(77 reference statements)

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“…Kosasih et al 3 15 reported a COF of 0.217 for 17R2 between Ti coated surfaces at 0.9 GPa pressure. These coefficients of friction are lower than the value of 0.675 at 1 GPa applied pressure for 16% 17R2 in the current model.…”

Section: Interfacialmentioning

confidence: 99%

“…15 The thickness of this adsorbed layer is ∼2.8 and ∼2.6 nm respectively for 17R2 and 17R4 on the Ti coated surface. 15 A film thicknesses of 1.77−2.56 nm has been observed for normal Pluronic adsorbed on the gold surface. 18 The distribution of copolymer on the surface is randomly, and the surface coverage of copolymer at this regime could be different so that the local concentration of copolymer is therefore considered in this investigation.…”

Section: ■ Introductionmentioning

confidence: 95%

“…The chosen asperities are consistent with the experimentally measured roughness of ∼2 nm of high Cr−steel balls. 15 The surfaces were then divided into three sublayers: rigid layers (1,4), thermostat layers (2,5), and deformable layers (3,6). 27 The lubricant was prepared by packing randomly the copolymer and water molecules in a rectangular box with initial dimensions of 215, 86, and 60 Å for X, Y, and Z directions, respectively.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The copolymer 17R2, as illustrated in Figure S1, is employed in this study. This copolymer has a chemical formula of H−[C*H−CH 2 15 −CH 3 , where C* is chiral carbon with an attached methyl group. To consider the influence of copolymer concentration, we used the lubricant with different concentrations between 1.0 and 20 wt % of the composition.…”

Section: ■ Introductionmentioning

confidence: 99%

“…This velocity is significantly larger than that applied in experiments (0.01−0.1 m.s −1 ) due to the expensive computation of MD. 15 The lowest shear rate that could be used in MD simulation is 10 7 s −1 ; however, the simulations should be carried out for up to 94 ns. 30 It is not easy to handle such a long calculation time for a huge model in MD simulation.…”

Section: ■ Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Tribological Behavior of Aqueous Copolymer Lubricant in Mixed Lubrication Regime

Zhu

et al. 2016

ACS Appl. Mater. Interfaces

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Although a number of experiments have been attempted to investigate the lubrication of aqueous copolymer lubricant, which is applied widely in metalworking operations, a comprehensive theoretical investigation at atomistic level is still lacking. This study addresses the influence of loading pressure and copolymer concentration on the structural properties and tribological performance of aqueous copolymer solution of poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) at mixed lubrication using a molecular dynamic (MD) simulation. An effective interfacial potential, which has been derived from density functional theory (DFT) calculations, was employed for the interactions between the fluid's molecules and iron surface. The simulation results have indicated that the triblock copolymer is physisorption on iron surface. Under confinement by iron surfaces, the copolymer molecules form lamellar structure in aqueous solution and behave differently from its bulk state. The lubrication performance of aqueous copolymer lubricant increases with concentration, but the friction reduction is insignificant at high loading pressure. Additionally, the plastic deformation of asperity is dependent on both copolymer concentration and loading pressure, and the wear behavior shows a linear dependence of friction force on the number of transferred atoms between contacting asperities.

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Section: Interfacialmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 95%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Tribological Behavior of Aqueous Copolymer Lubricant in Mixed Lubrication Regime

Zhu

et al. 2016

ACS Appl. Mater. Interfaces

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Thickness and scratch resistance of adsorbed film formed by triblock symmetrical copolymer solutions

Kosasih

Novareza

Zhu

et al. 2016

Lubrication Science

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The thickness and scratch resistance of adsorbed films formed on mild steel samples (MS1020), which have been immersed in water copolymer solutions, are reported. The effects of bulk temperature and the copolymer structures, normal, poly(ethylene oxide)m‐poly(propylene oxide)n‐poly(ethylene oxide)m, and reverse, poly(propylene oxide)n‐poly(ethylene oxide)m‐poly(propylene oxide)n, are elucidated. The films' thicknesses are independent of structure but not of temperature. The adsorbed films of above cloud point solutions are thicker than below cloud point. However, nanoscratch experiments carried out to measure the scratch resistance of the films reveal that despite of thicker film formed by above cloud point solutions, it is relatively more prone to being detached than the thinner films of below cloud point solutions. The effect of extreme pressure additive, alkyl phosphate ester (APE), is also investigated suggesting the normal copolymer has comparable scratch resistance with APE when used at below the cloud point. Copyright © 2016 John Wiley & Sons, Ltd.

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Growth of adsorbed additive layer for further friction reduction

Hirayama

Maeda²,

Sasaki

et al. 2018

Lubrication Science

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Boundary lubrication is one of the most interesting topics in the field of tribology, and a lot of studies have been conducted from the past for understanding the behaviour of boundary lubrication films. General boundary lubrication films are formed by the adsorption of additives mixed into lubricant, and then the tribological performances are drastically improved in many cases. However, there is still room for discussion on the “actual” behaviour of adsorbed additive layer in the tribological condition, that is, under high pressure and/or with external forces. This paper showed the “growing” behaviour of an adsorbed additive layer onto metal surface due to high pressure by means of neutron reflectometry in conjunction with the result obtained through cross‐sectional imaging by frequency‐modulation atomic force microscopy. In addition, the nanotribological study using atomic force microscopy with a colloidal probe showed that the coefficient of friction in the pre‐scratched area was lower than that in the non‐scratched area and that the reduction ratio for lubricant with additive was higher than that for lubricant without additive. This result indicates that growth of the adsorbed additive layer contributed more greatly to a reduction in the coefficient of friction.

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Adsorbed film structure and tribological performance of aqueous copolymer lubricants with phosphate ester additive on Ti coated surface

Cited by 15 publications

References 51 publications

Tribological Behavior of Aqueous Copolymer Lubricant in Mixed Lubrication Regime

Tribological Behavior of Aqueous Copolymer Lubricant in Mixed Lubrication Regime

Thickness and scratch resistance of adsorbed film formed by triblock symmetrical copolymer solutions

Growth of adsorbed additive layer for further friction reduction

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