Speed dependence of liquid superlubricity stability with H<sub>3</sub>PO<sub>4</sub> solution

Xiao, Chen; Li, Jinjin; Chen, Lei; Zhang, Chenhui; Zhou, Ningning; Qian, Linmao

doi:10.1039/c7ra09217b

Cited by 13 publications

(7 citation statements)

References 33 publications

(36 reference statements)

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“…The chemical and physical properties of adsorbed liquids, such as chemical activity, surface energy, viscosity, molecular configuration, molecular polarity, cationic species, are likely to become important determinants. They may induce interfacial tribochemical reactions, hydrodynamic effects, ion exchanges, liquid-solid phase transitions, thereby affecting the interfacial adhesion and friction forces [15,[155][156][157][158].…”

Section: Perspectivesmentioning

confidence: 99%

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Xiao

Shi

et al. 2019

Colloids and Interfaces

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Most inorganic material surfaces exposed to ambient air can adsorb water, and hydrogen bonding interactions among adsorbed water molecules vary depending on, not only intrinsic properties of material surfaces, but also extrinsic working conditions. When dimensions of solid objects shrink to micro- and nano-scales, the ratio of surface area to volume increases greatly and the contribution of water condensation on interfacial forces, such as adhesion (Fa) and friction (Ft), becomes significant. This paper reviews the structural evolution of the adsorbed water layer on solid surfaces and its effect on Fa and Ft at nanoasperity contact for sphere-on-flat geometry. The details of the underlying mechanisms governing water adsorption behaviors vary depending on the atomic structure of the substrate, surface hydrophilicity and atmospheric conditions. The solid surfaces reviewed in this paper include metal/metallic oxides, silicon/silicon oxides, fluorides, and two-dimensional materials. The mechanism by which water condensation influences Fa is discussed based on the competition among capillary force, van der Waals force and the rupture force of solid-like water bridge. The condensed meniscus and the molecular configuration of the water bridge are influenced by surface roughness, surface hydrophilicity, temperature, sliding velocity, which in turn affect the kinetics of water condensation and interfacial Ft. Taking the effects of the thickness and structure of adsorbed water into account is important to obtain a full understanding of the interfacial forces at nanoasperity contact under ambient conditions.

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Section: Perspectivesmentioning

confidence: 99%

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Xiao

Shi

et al. 2019

Colloids and Interfaces

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“…However, inappropriate conditions during the running-in process still lead to the negative results of achieving superlubricity in most water-based systems. Large load, too low or too high speed, or suboptimal pH value of the solution during the running-in process can all result in superlubricity failure (Li et al, 2014;Xiao et al, 2017;Jiang et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the running-in process in photoinduced superlubricity

Han

Ma²,

Ma³

et al. 2023

Front. Mater.

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Photoinduced superlubricity on TiO2 surfaces is a newfound phenomenon which draws researchers’ attention. This study provides a new method to achieve superlubricity (COF<0.01) with an external light field. However, photoinduced superlubricity can only be realized under specific conditions. Improper running-in conditions, such as speed, load, and pH value, will lead to superlubricity failure even after ultraviolet illumination on the TiO2 surface. In this paper, different running-in loads, speeds, or pH values were used in the experiment of photoinduced superlubricity, and the worn surfaces after running-in and testing in 70% v/v glycerol aqueous solution were investigated thoroughly. Results reveal that the morphology of worn scars differs under different running-in conditions. While the running-in speeds and loads are too low (<0.03 m/s and <2 N) or too large (>0.1 m/s and >9 N), the photoinduced superlubricity will fail because of wrong lubrication state. When the pH value of running-in solution is less than 4.5, photoinduced superlubricity is easier to achieve. In discuss, mixed lubrication is believed to be the key to success of photoinduced superlubricity, because the elastohydrodynamic effect, doublelayer effect and adsorption of glycerol molecules works at the same time. In addition, due to the formation of the SiO2 layer on the Si3N4 ball and better attraction to lubricant molecules with hydroxyl radicals on the TiO2 surface, running-in in solutions with low pH values contributes to the success of photoinduced superlubricity. In any event, the ultraviolet illumination can reduce the friction coefficient of the TiO2/Si3N4 tribological system and can realize photoinduced superlubricity under appropriate running-in conditions.

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“…Until now, superlubricity could be realized by various liquid lubricant systems, such as hydrophilic polymer brushes [7], ionic liquid [8,9], polyhydroxy aqueous solutions [10][11][12][13], acid-based solutions [14][15][16] and two-dimensional (2D) nano-additives, after a period of running-in. Compared with other liquid lubricant systems, the introduction of 2D nano-additives efficiently enhances the contact pressure of the lubricants.…”

Section: Introductionmentioning

confidence: 99%

Macroscale Superlubricity of Black Phosphorus Quantum Dots

Gong

Wang

et al. 2022

Lubricants

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In the present work, Black Phosphorus Quantum Dots (BPQDs) were synthesized via sonication-assisted liquid-phase exfoliation. The average size of the BPQDs was 3.3 ± 0.85 nm. The BPQDs exhibited excellent dispersion stability in ultrapure water. Macroscale superlubricity was realized with the unmodified BPQDs on rough Si3N4/SiO2 interfaces. A minimum coefficient of friction (COF) of 0.0022 was achieved at the concentration of 0.015 wt%. In addition, the glycerol was introduced to promote the stability of the superlubricity state. The COF of the BPQDs-Glycerol aqueous solution (BGaq) was 83.75% lower than that of the Glycerol aqueous solution (Gaq). Based on the above analysis, the lubrication model was presented. The hydrogen-bonded network and silica gel layer were formed on the friction interface, which played a major role in the realization of macroscale superlubricity. In addition, the adsorption water layer could also prevent the worn surfaces from making contact with each other. Moreover, the synergistic effect between BPQDs and glycerol could significantly decrease the COF and maintain the superlubricity state. The findings theoretically support the realization of macroscale superlubricity with unmodified BPQDs as a water-based lubrication additive.

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Speed dependence of liquid superlubricity stability with H₃PO₄ solution

Abstract: The water-based superlubricity can be promoted to a high-speed of 1.6 m s−1 after pre-running-in at low-speed of 0.075 m s−1.

Cited by 13 publications

References 33 publications

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Investigation of the running-in process in photoinduced superlubricity

Macroscale Superlubricity of Black Phosphorus Quantum Dots

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Speed dependence of liquid superlubricity stability with H3PO4 solution

Abstract: The water-based superlubricity can be promoted to a high-speed of 1.6 m s−1 after pre-running-in at low-speed of 0.075 m s−1.

Cited by 13 publications

References 33 publications

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Thickness and Structure of Adsorbed Water Layer and Effects on Adhesion and Friction at Nanoasperity Contact

Investigation of the running-in process in photoinduced superlubricity

Macroscale Superlubricity of Black Phosphorus Quantum Dots

Contact Info

Product

Resources

About

Speed dependence of liquid superlubricity stability with H₃PO₄ solution