Synergistic lubrication of organic friction modifiers in boundary lubrication regime by molecular dynamics simulations

Shi, Junqin; Li, Hang; Lü, Yang; Sun, Lin; Xu, Shiqiang; Fan, Xiaoli

doi:10.1016/j.apsusc.2023.157087

Cited by 5 publications

(1 citation statement)

References 34 publications

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“…Typical OFM molecules comprise at least one polar head group and one alkyl chain tail. Previous studies have suggested that OFMs form adsorbed films on sliding surfaces, preventing direct solid-solid contacts, thereby reducing friction in the boundary and mixed lubrication regime [6,[10][11][12]. The chemistry of OFMs and solid surfaces determines their interaction strength.…”

Section: Introductionmentioning

confidence: 99%

Coarse-Grained Molecular Dynamics Simulations of Organic Friction Modifier Adsorption on Rough Surfaces under Shear

Tang,

Chong,

Zhang

2024

Lubricants

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Reducing friction energy losses is crucial in mechanical systems, often achieved through lubrication strategies employing friction modifiers. These additives adsorb onto surfaces, forming boundary film to prevent solid–solid contacts. However, atomistic simulation techniques used to study these additives often ignore surface roughness due to high computational cost. This study addresses this gap by employing Coarse-Grained Molecular Dynamics (CG MD) to investigate the impact of surface roughness on the adsorption of Organic Friction Modifiers (OFMs) under shear. Traditional self-diffusion methods prove inadequate for determining the damping coefficients in CG models because of strong OFM adsorption effects. Therefore, shear-induced motion is introduced for the coefficient determination. The simulation reveals that a symmetrical model (identical opposing surfaces) shows OFM slip, desorption, and re-adsorption trends on rough surfaces, while an asymmetrical model (smooth cylinder on a flat surface) demonstrates increased adsorption on rough flat surfaces (up to 60.9%) compared to smooth flat surfaces under similar shearing conditions. However, rough flat surfaces with a smaller wavelength (6 nm) exhibit faster OFM desorption along the asperity region, up to four times more than a 24 nm wavelength surface. This research emphasizes the importance of considering surface roughness in simulating OFM behavior for lubrication applications.

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Section: Introductionmentioning

confidence: 99%

Coarse-Grained Molecular Dynamics Simulations of Organic Friction Modifier Adsorption on Rough Surfaces under Shear

Tang,

Chong,

Zhang

2024

Lubricants

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Coarse-Grained Molecular Dynamics Simulations of Nanoscale Roughness Effects on Oil Film Delamination

Deng,

Kubo,

Todaka

et al. 2024

Tribol Lett

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In boundary lubrication, the detachment of lubricant molecules from a solid surface is likely to occur due to the presence of high compressive normal stress combined with shear stress exerted on the solid–liquid interface. This phenomenon often results in a delamination behavior at the interface. We aim to investigate the nanoscale roughness effect on the oil film delamination from sliding iron surfaces with grain boundaries by coarse-grained molecular dynamics simulations. As a result, the oil film delamination was effectively suppressed in higher roughness. Two distinct mechanisms of delamination were found depending on surface roughness when the critical normal stress is exceeded. High roughness enhanced the ability to prevent complete slip but had negligible influence on partial slip. Graphical Abstract

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Nonequilibrium molecular dynamics investigation on friction behavior of organic friction modifiers under dynamic load

Wei,

Gao,

2024

Journal of Molecular Liquids

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Synergistic lubrication of organic friction modifiers in boundary lubrication regime by molecular dynamics simulations

Cited by 5 publications

References 34 publications

Coarse-Grained Molecular Dynamics Simulations of Organic Friction Modifier Adsorption on Rough Surfaces under Shear

Coarse-Grained Molecular Dynamics Simulations of Organic Friction Modifier Adsorption on Rough Surfaces under Shear

Coarse-Grained Molecular Dynamics Simulations of Nanoscale Roughness Effects on Oil Film Delamination

Nonequilibrium molecular dynamics investigation on friction behavior of organic friction modifiers under dynamic load

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