Enhanced superlubricity on a-C films by lubrication with 3-hydroxypropionic acid

Sun, Shouyi; Li, Jianfeng; Li, Jinjin; Luo, Jianbin

doi:10.1016/j.carbon.2022.07.062

Cited by 17 publications

(13 citation statements)

References 38 publications

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“…Additionally, a superlubricity model was proposed herein to elucidate the superlubricity mechanism (Figure ). At the initial stage of friction, the passivation layer of the a-C film was removed, and numerous carbon dangling bonds were exposed, which provided multiple reaction sites for the chemisorption of LC molecules through the interaction between carboxylate radicals and the carbon atoms . After the chemisorption of LC molecules, the exposed carboxylate radicals can bond with the lithium ions via the electrostatic interaction.…”

Section: Resultsmentioning

confidence: 99%

“…The elemental distribution along the depth of the Si 3 N 4 ball exhibited large oxygen content in Region A, owing to the chemically adsorbed LC molecules and the generated colloidal silica (Figure b). The relatively large oxygen content in the chromium layer was due to the oxidation during the deposition of chromium . Moreover, no remarkable carbon signal was detected in the tribochemical film, indicating weak chemisorption of LC molecules on the Si 3 N 4 ball.…”

Section: Resultsmentioning

confidence: 99%

“…The relatively large oxygen content in the chromium layer was due to the oxidation during the deposition of chromium. 23 Moreover, no remarkable carbon signal was detected in the tribochemical film, indicating weak chemisorption of LC molecules on the Si 3 N 4 ball. However, the tribochemical film on the a-C film was thicker (5 nm) than that on the Si 3 N 4 ball (Figure 8c).…”

Section: Wear Propertiesmentioning

confidence: 98%

“…At the initial stage of friction, the passivation layer of the a-C film was removed, and numerous carbon dangling bonds were exposed, which provided multiple reaction sites for the chemisorption of LC molecules through the interaction between carboxylate radicals and the carbon atoms. 23 After the chemisorption of LC molecules, the exposed carboxylate radicals can bond with the lithium ions via the electrostatic interaction. However, the interaction between LC molecules and Si 3 N 4 was weak, with little adsorption of the LC molecules in the wear scar.…”

Section: Mechanism Of Superlubricity and Near-zeromentioning

confidence: 99%

“…The solid–liquid lubricating system can effectively avoid the influence of the atmospheric environment on friction. , It has been found that superlubricity could be achieved on the tetrahedral amorphous carbon film by lubricating with pure glycerol, and the surface polishing and hydroxyl terminations of the DLC film were the key factors for obtaining super-low COF. , The oleic acid could trigger superlubricity on the DLC film because its carboxylic polar head and double bond of carbon were likely to anchor on the surface carbon atoms, destroying the oleic acid molecules under large shear stress and generating a dense surface passivation layer on the DLC film with various functional groups. − Moreover, superlubricity could be realized on the DLC film with the lubrication of a carboxylic acid, which was attributed to the chemically adsorbed carboxylic molecular layer . Additionally, a super-low COF of 0.006 was obtained on the DLC film when glycerol monooleate was added to the poly-α-olefin-based synthetic oil as an additive.…”

Section: Introductionmentioning

confidence: 99%

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Lithium Citrate Triggered Macroscopic Superlubricity with Near-Zero Wear on an Amorphous Carbon Film

Sun

et al. 2023

ACS Appl. Mater. Interfaces

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An amorphous carbon (a-C) film shows substantial potential for friction and wear reduction. In this work, the robust superlubricity state with a coefficient of friction of 0.002 at the maximal pressure of 1.15 GPa was realized when lithium citrate (LC) was applied as the lubricating additive in ethylene glycol (EG) to lubricate the Si 3 N 4 /a-C friction pair based on the ball-onplate friction test. The wear rate of the a-C film was 4.5 × 10 −10 mm 3 /N•m, which was reduced by 98.3% compared to that of the film lubricated with EG. Friction promoted the chemisorption of the LC molecules via the tribochemical reaction between the carboxylate radicals and the a-C film. The exposed lithium ions could adsorb water molecules to form a hydration layer, providing extremely low shear strength. Furthermore, the colloidal silica layer formed on the Si 3 N 4 ball via the tribochemical reaction could reduce friction. It was difficult to destroy the formed tribochemical films under high contact pressure because they were robust, preventing the direct contact of the friction pair and resulting in the near-zero wear of the a-C film.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Wear Propertiesmentioning

confidence: 98%

Section: Mechanism Of Superlubricity and Near-zeromentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Lithium Citrate Triggered Macroscopic Superlubricity with Near-Zero Wear on an Amorphous Carbon Film

Sun

et al. 2023

ACS Appl. Mater. Interfaces

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Macro‐Superlubricity Induced by Tribocatalysis of High‐Entropy Ceramics

Du,

Yu,

Sui

et al. 2024

Advanced Materials

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Macroscale superlubricity has attracted considerable attention as a promising strategy to minimize frictional energy dissipation and achieve near‐zero wear. However, realizing macroscale superlubricity with prolonged durability remains an immense challenge, particularly on engineering steels. Current superlubricants render steel surfaces susceptible to corrosion, causing severe wear and superlubrication failure. Herein, high‐entropy ceramics (HEC) with catalytic properties are innovatively introduced to prevent corrosion of engineering steels and achieve macro‐superlubricity through tribo‐catalytic effect. Furthermore, this catalytically induced superlubricity system exhibits an ultra‐low friction coefficient of 0.0037 under contact pressure up to 1.47 GPa, an ultra‐long cycle lifetime of 1.25 × 106 cycles (corresponding sliding distance up to 5 km), and an extremely low wear rate of 3.032 × 10−10 mm3·N−1·m−1 on the HEC surface. Based on the experimental analysis and theoretical simulation, the in situ formed HEC nanocrystals reduce the Gibbs free energy of hydrolysis of PA molecules into inositol and phosphoric acid molecules in the lubricant. Notably, the hydrolysis products favorably contributed to the reduction of shear force in the lubrication system, which is essential for achieving macroscale superlubricity over a long time. This study provides a new perspective for designing robust superlubricity systems by harnessing the tribocatalytic effect of high‐entropy materials.

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