Molecular dynamics simulation of the lubricant conformation changes and energy transfer of the confined thin lubricant film

Liu, Dongjie; Li, Haipeng; Huo, Lixia; Wang, Kang; Sun, Kening; Wei, Jinjia; Chen, Fei

doi:10.1016/j.ces.2023.118541

Cited by 11 publications

(8 citation statements)

References 54 publications

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“…33 Based on the fact that the carbon tribofilm was formed under an extreme loading condition, 34 the applied load σ z on the top rigid layer was set to three values, 1, 2, and 3 GPa, respectively. 35,36 The sliding velocity V x was set to 20 m/s with a simulation time of 250 ps. In this study, four intensity values…”

Section: ■ Simulation Model and Methodsmentioning

confidence: 99%

“…The velocity verlet algorithm was used to solve the motion of particles . Based on the fact that the carbon tribofilm was formed under an extreme loading condition, the applied load σ z on the top rigid layer was set to three values, 1, 2, and 3 GPa, respectively. , The sliding velocity V x was set to 20 m/s with a simulation time of 250 ps. In this study, four intensity values E (i.e., E 0 = 0 V/Å, E 1 = 1 × 10 –3 V/Å, E 2 = 1 × 10 –2 V/Å, and E 3 = 1 × 10 –1 V/Å) were applied to ZnO.…”

Section: Simulation Model and Methodsmentioning

confidence: 99%

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Investigation of Tribological Behavior and Lubrication Mechanisms of Zinc Oxide under Poly α-olefin Lubrication Enhanced by the Electric Field

Chen,

Ji,

Zhang

et al. 2024

Langmuir

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The electric field induces complex effects on the tribological properties of zinc oxide (ZnO) under lubricated conditions, particularly at the nanoscale, where the friction process and mechanism remain unclear. In this paper, the tribological behaviors of ZnO under the lubrication of poly α-olefins (PAO) were investigated by molecular dynamics (MD) simulations with reactive force field (ReaxFF). The results reveal a significant enhancement in the tribological performances of ZnO with the application of the electric field, resulting in a 58.6% reduction in the coefficient of friction (COF) from 0.193 at 0 V/Å to 0.080 at 0.1 V/Å. This improvement can be attributed to the weakening of interfacial interaction, evidenced by a reduction in the number of C−O covalent bonds under the influence of the electric field, along with the formation of an adsorption film due to applied load and shear effects. Notably, the effect of the electric field and applied load extends the impact of interface slip on the tribological performance of ZnO. Overall, this study provides a comprehensive understanding of the impact of the electric field on reducing the friction of ZnO-based structured models, shedding light on explaining their tribological properties and lubrication mechanisms.

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Section: ■ Simulation Model and Methodsmentioning

confidence: 99%

Section: Simulation Model and Methodsmentioning

confidence: 99%

Investigation of Tribological Behavior and Lubrication Mechanisms of Zinc Oxide under Poly α-olefin Lubrication Enhanced by the Electric Field

Chen,

Ji,

Zhang

et al. 2024

Langmuir

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show abstract

“…The structural changes in the ‘sandwich model’ before and after loading are shown in Figure 13 . Shear process: After the completion of the load iron wall surface, the system continued using the NVT system, namely, the lubricant system using the NVE system, to simulate the lubricant in the shear process and produce the shear heat phenomenon [ 28 , 29 ]. The NVT ensemble is a canonical ensemble, which is a collection of systems with the same number of molecules N, the same volume V, and the same temperature T, represented by the symbol (N, V, T).…”

Section: Methodsmentioning

confidence: 99%

“…The structural changes in the 'sandwich model' before and after loading are shown in Figure 13. (3) Shear process: After the completion of the load iron wall surface, the system continued using the NVT system, namely, the lubricant system using the NVE system, to simulate the lubricant in the shear process and produce the shear heat phenomenon [28,29].…”

Section: Shear Simulation Of Single Lubricant Structurementioning

confidence: 99%

The Simulation of Ester Lubricants and Their Application in Weak Gel Drilling Fluids

Dai,

Lu,

Tang

et al. 2024

Gels

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To enhance the performance and reduce the amount of ester-based lubricants used in weak gel drilling fluids, a shear dynamics simulation under extreme pressure conditions was employed to refine the formulation of the base oil and pressure additives. The simulation results were validated using fatty acid methyl, ethyl, and butyl esters. Fatty acid methyl ester demonstrated the lowest temperature increase and the highest load-bearing capacity post-shear. The four-ball friction test revealed that methyl oleate had a coefficient of friction of 0.0018, approximately a third of that for butyl oleate, confirming the simulation’s accuracy. By using methyl oleate as the base oil and oleamide as the pressure-resistant component, the optimal shear stress was achieved with a 10% addition of oleamide. A lubricant composed of 90% methyl oleate and 10% oleamide was tested and showed a coefficient of friction of 0.03 when 0.5% was added to bentonite slurry, indicating a strong lubricating film. Adding 1% of this lubricant to a low gel drilling fluid system did not affect its rheological properties, and the gel structure remained stable after seven days of aging. Field tests at the Fu86-3 well in the Jiangsu Oilfield of Sinopec confirmed that adding 1% of the ester-based lubricant to the drilling fluid significantly improved drilling efficiency, reduced drag by an average of 33%, and increased the drilling rate to 22.12 m/h. This innovation effectively prevents drilling complications and successfully achieves the objectives of enhancing efficiency.

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“…Liu et al explored conformational changes of perfluoropolyethers (PFPE) as the lubricant under high pressure lubrication conditions (Figure 12). The results demonstrated that at 1.0 GPa, the bond lengths and bond angles changed significantly within the first 0.8 ns, after which they almost reached a steady state [82].…”

Section: Conformation Of Polymersmentioning

confidence: 95%

Molecular Dynamics Simulation on Polymer Tribology: A Review

Yin,

Wang,

Guo

et al. 2024

Lubricants

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A profound comprehension of friction and wear mechanisms is essential for the design and development of high-performance polymeric materials for tribological application. However, it is difficult to deeply investigate the polymer friction process in situ at the micro/mesoscopic scale by traditional research methods. In recent years, molecular dynamics (MD) simulation, as an emerging research method, has attracted more and more attention in the field of polymer tribology due to its ability to show the physicochemical evolution between the contact interfaces at the atomic scale. Herein, we review the applications of MD in recent studies of polymer tribology and their research focuses (e.g., tribological properties, distribution and conformation of polymer chains, interfacial interaction, frictional heat, and tribochemical reactions) across three perspectives: all-atom MD, reactive MD, and coarse-grained MD. Additionally, we summarize the current challenges encountered by MD simulation in polymer tribology research and present recommendations accordingly, aiming to provide several insights for researchers in related fields.

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Molecular dynamics simulation of the lubricant conformation changes and energy transfer of the confined thin lubricant film

Cited by 11 publications

References 54 publications

Investigation of Tribological Behavior and Lubrication Mechanisms of Zinc Oxide under Poly α-olefin Lubrication Enhanced by the Electric Field

Investigation of Tribological Behavior and Lubrication Mechanisms of Zinc Oxide under Poly α-olefin Lubrication Enhanced by the Electric Field

The Simulation of Ester Lubricants and Their Application in Weak Gel Drilling Fluids

Molecular Dynamics Simulation on Polymer Tribology: A Review

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