Effect of Surrounding Atmosphere on Friction Properties of Hydrophobic and Hydrophilic Ionic Liquids

Kawada, Shouhei; Sasaki, Shinya; Miyatake, Masaaki

doi:10.2474/trol.14.285

Cited by 3 publications

(5 citation statements)

References 57 publications

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“…Their chemical structures and purity are presented in Table 1. [BMIM] [PF6] was chosen as a reference due to its hydrophobicity, which ensures stable lubricity results in different ambient conditions [31,44]. environment.…”

Section: Methodsmentioning

confidence: 99%

“…[BMIM] [PF6] was chosen as a reference due to its hydrophobicity, which ensures stable lubricity results in different ambient conditions [31,44].…”

Section: Methodsmentioning

confidence: 99%

“…They also revealed that an increased test temperature decreases the ratio, decreasing ILs' positive effect on lubricity. Kawada et al made a great effort to uncover the lubrication mechanisms of different cyano-based anions with imidazolium and phosphonium cations [29][30][31][32][33][34]. One of their studies demonstrated how different ciano-based anions combined with an imidazolium cation can alter the lubrication mechanisms of H-free DLC [34].…”

Section: Introductionmentioning

confidence: 99%

“…In most cases, the ambient conditions are of great importance, too. It was shown that hydrophilic ILs lose their lubricity in specific ambient humidity [29,31,40]. On the other hand, some ILs demonstrated extremely low friction when humidity was present [41][42][43].…”

Section: Introductionmentioning

confidence: 99%

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A Comparison of the Tribological Properties of Two Phosphonium Ionic Liquids

Horng,

Ta,

Kreivaitis

et al. 2024

Lubricants

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For over two decades, ionic liquids have been among the most exciting lubrication topics. Ionic liquids were investigated by using them as neat lubricants and lubricity-enhancing additives. However, new and unique features were revealed by introducing new ionic liquids. This paper compares the tribological properties of two ionic liquids with the same trihexyltetradecylphosphonium [P 6,6,6,14] cation and different anions—dicyanamide [DCN] and bis(2,4,4-trimethylpentyl)phosphinate. The widely investigated 1-Butyl-3-methylimidazolium hexafluorophosphate [BMIM] [PF6] ionic liquid was used as a reference. The lubricity was comprehensively investigated using two testing modes: reciprocation in a ball-on-plate tribometer and continuous sliding in a ball-on-disc tribometer. The tests were performed at temperatures of 30 and 80 °C. The friction, wear, and film thickness were evaluated, and a worn surface analysis was conducted. It was found that in the case of reciprocation, anion has a significant effect on the lubricity. The difference was particularly evident when the results at two temperatures were compared. The ability to build a low-friction tribo-film was suggested as the primer source of lubricity. In the case of continuous sliding, the differences were not as noticeable. In this case, viscosity was assigned to be the leading property.

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Section: Methodsmentioning

confidence: 99%

“…[BMIM] [PF6] was chosen as a reference due to its hydrophobicity, which ensures stable lubricity results in different ambient conditions [31,44].…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Comparison of the Tribological Properties of Two Phosphonium Ionic Liquids

Horng,

Ta,

Kreivaitis

et al. 2024

Lubricants

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“…For example, it has been reported that water molecules can cause corrosive wear on metallic sliding materials under lubrication with fluorine-based ionic liquids [19,28]. In the case of ionic liquids that form an adsorption layer, water molecules destroy this layer at the friction interface and cause the deterioration of the lubricating properties [29][30][31]. Therefore, the practical use of ionic liquids as liquid lubricants and friction manipulation systems requires that the effects of moisture in the friction atmosphere on their lubricating properties must be clarified.…”

Section: Introductionmentioning

confidence: 99%

Effects of Relative Humidity on Lubricating Properties of Ionic Liquids

Kawada

Tanji

Kobayashi

et al. 2023

e-J. Surf. Sci. Nanotechnol.

Self Cite

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Minimizing friction losses in mechanical systems is essential for realizing a low-carbon society, as it will result in energy and resource conservation. In this study, we focused on the suitability of ionic liquids that form an electric double layer for use as liquid lubricants. Ionic liquids have been reported to exhibit ultralow friction with friction coefficients of less than 0.01. However, it is necessary to elucidate the effects of water on their lubricating properties, as water can cause corrosive wear on metallic sliding materials during lubrication using fluorine-based ionic liquids. In addition, water destroys the layer formed at the friction interface and adversely affects the lubricating properties. Here, we investigated the lubricating properties and lubricating mechanisms of both hydrophilic (1-butyl-3-methylimidazolium dicyanamide [BMIM][DCN] and 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ]), and hydrophobic (1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF 6 ] and 1butyl-3-methylimidazolium tris (perfluoroalkyl) trifluorophosphate [BMIM][FAP]) ionic liquids at different relative humidity (RH) levels (15, 50, and 80%). [BMIM][DCN] exhibited good lubricating properties at 15% RH because of the formation of an adsorption layer derived from both types of ions. However, the adsorption layer was destroyed by water molecules as the humidity was increased. [BMIM][BF 4 ] also exhibited good lubricating properties at 15% RH. This ionic liquid formed a chemical layer as well as an adsorption layer. However, these layers were destroyed by water molecules at 50 and 80% RH. In the case of [BMIM][PF 6 ] too, a chemical layer and an adsorption layer were formed at 15 and 50% RH, and these layers exhibited the best lubricating properties. On the other hand, the layers were destroyed by water molecules at 80% RH. Finally, [BMIM][FAP] exhibited good lubricating properties even under high-RH conditions because this ionic liquid was the most hydrophobic.

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