Tribochemical Reactions of Ionic Liquids Under Vacuum Conditions

Kawada, Shouhei; Watanabe, Seiya; Kondo, Yuriko; Tsuboi, Ryo; Sasaki, Shinya

doi:10.1007/s11249-014-0342-z

Cited by 24 publications

(17 citation statements)

References 10 publications

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“…According to the SEM-EDS analysis, the oxide film was removed by the sliding under vacuum conditions. This exposed the nascent surface, which functioned as a catalyst [28,33,35,36]. The cyano-based ionic liquids interacted with this nascent surface and underwent catalytic decomposition, during which only the anion was adsorbed on the worn surface because of electrical forces; nascent steel surfaces have positive charges [35,37] The friction coefficients of both the cyano-based ionic liquids in dry air were higher than those in vacuum.…”

Section: Tof-sims Analysis Resultsmentioning

confidence: 99%

“…The tribological properties of the cyano-based ionic liquids under air, vacuum, and dry air conditions were evaluated using an atmosphere-controlled ball-on-disk friction tester [28]. Prior to the sliding tests, the specimens were ultrasonically cleaned with a mixed solution of petroleum benzine and acetone in the ratio of 1:1 for 20 min.…”

Section: Sliding Testsmentioning

confidence: 99%

“…Especially, tetrafluoroborate and hexafluorophosphate undergo hydrolysis when exposed to moisture and generate hydrogen fluoride even without sliding [25][26][27]. To prevent corrosion, use of fluorinefree ionic liquids, such as bis(oxalato)borate, ethylsulfate, diethylphosphate, dicyandiamide, tricyanomethane, and tetracyanoborate has been explored [28][29][30][31][32][33]. These ionic liquids do not have fluorine in their chemical strucutres, and therefore, they have a low risk of corrosion damage.…”

Section: Introductionmentioning

confidence: 99%

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Tribological Properties of Cyano-Based Ionic Liquids under Different Environments

Kawada

Sasaki

2018

Tribology Online

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Ionic liquids have been used as novel high-performance lubricants. However, fluorine-based ionic liquids cause corrosion of materials by the formation of FeF 2 and FeF 3 . This study focuses on cyano-based ionic liquids, as they have low corrosion tendencies owing to the absence of fluorine in their structures. However, cyano-based ionic liquids are hydrophilic, and hence, the effect of ambient conditions (e.g., atmospheric moisture) on the tribological properties needs to be investigated. This study reports the tribological properties of two types of cyano-based ionic liquids 1-ethyl-3-methylimidazolium dicyanamide and 1-ethyl-3-methylimidazolium tricyanomethane under air, vacuum, and dry air environments. Their friction coefficients were found to be dependent on the ambient condition. Both the ionic liquids exhibited low friction coefficients in vacuum. The time-of-flight secondary ion mass spectrometry results indicated that the anion was adsorbed on the worn surface under vacuum conditions, and the adsorbed anion exhibited a low friction. In dry air, the cation was adsorbed on the worn surface, and the adsorbed cation exhibited a higher friction coefficient than the adsorbed anion. In air, the cyano-based ionic liquids caused corrosion of the sliding material and exhibited a high friction coefficient, because of the absorption of moisture from air.

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Section: Tof-sims Analysis Resultsmentioning

confidence: 99%

Section: Sliding Testsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tribological Properties of Cyano-Based Ionic Liquids under Different Environments

Kawada

Sasaki

2018

Tribology Online

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“…[67][68][69][70][71][72] We also exclude studies where the reaction was not carried out in situ, that is, spectra were not recorded while the reaction proceeded, or the sample was moved to a different site in the XPS setup or was even removed from the XPS setup in order to carry out the reaction. [73][74][75][76][77] We also do not address studies that incorporate electrochemical sample manipulation, 66,67,[69][70][71][78][79][80][81][82][83][84][85][86] electrodeposition of metal or organic layers from ILs, [87][88][89][90][91] and IL decomposition 84,[92][93][94][95][96][97][98][99][100][101][102] or nanoparticle formation in ILs. 62,75,103 Each of these topics was studied extensively and would justify a separate review.…”

Section: Introductionmentioning

confidence: 99%

Perspective: Chemical reactions in ionic liquids monitored through the gas (vacuum)/liquid interface

Maier

Niedermaier

Steinrück

2017

The Journal of Chemical Physics

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This perspective analyzes the potential of X-ray photoelectron spectroscopy under ultrahigh vacuum (UHV) conditions to follow chemical reactions in ionic liquids in situ. Traditionally, only reactions occurring on solid surfaces were investigated by X-ray photoelectron spectroscopy (XPS) in situ. This was due to the high vapor pressures of common liquids or solvents, which are not compatible with the required UHV conditions. It was only recently realized that the situation is very different when studying reactions in Ionic Liquids (ILs), which have an inherently low vapor pressure, and first studies have been performed within the last years. Compared to classical spectroscopy techniques used to monitor chemical reactions, the advantage of XPS is that through the analysis of their core levels all relevant elements can be quantified and their chemical state can be analyzed under well-defined (ultraclean) conditions. In this perspective, we cover six very different reactions which occur in the IL, with the IL, or at an IL/support interface, demonstrating the outstanding potential of in situ XPS to gain insights into liquid phase reactions in the near-surface region.

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“…A new family of experimental techniques that combine tribometry with mass spectrometry or surface sensitive techniques has recently emerged [48][49][50][51][52][53][54]. These new techniques can provide important information on the development of tribochemical processes in the course of a tribological test.…”

Section: Introductionmentioning

confidence: 99%

Time-Resolved Characterization of Dynamic Tribochemical Processes for Dicationic Imidazolium Ionic Liquid

et al. 2017

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Dynamic tribochemical processes for dicationic ionic liquid containing a geminal imidazolium cation head group bridged by a poly(ethylene glycol) and a bis(trifluoromethylsulfonyl)imide anion were studied using time-resolved mechanically stimulated gas emission mass-spectrometry (MSGE-MS). In comparison with similar monocationic imidazolium ionic liquids with short alkyl or long polyether side chains, the dicationic ionic liquid had a lower coefficient of friction on Ti6Al4V alloy and smoother behavior. The analysis of volatile decomposition products suggested multiple tribochemical reactions in which both anionic and cationic moieties are involved. The tribochemical degradation of cations was mainly through the detachment of the side and bridging chains from the imidazolium head groups. The absence of volatile products containing nitrogen implies that the imidazole group remained unchanged. Hydrogen and water desorption were attributed to the reactions of hydrogen fluoride being a product of anion degradation with titanium and titanium oxide, respectively.

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Tribochemical Reactions of Ionic Liquids Under Vacuum Conditions

Cited by 24 publications

References 10 publications

Tribological Properties of Cyano-Based Ionic Liquids under Different Environments

Tribological Properties of Cyano-Based Ionic Liquids under Different Environments

Perspective: Chemical reactions in ionic liquids monitored through the gas (vacuum)/liquid interface

Time-Resolved Characterization of Dynamic Tribochemical Processes for Dicationic Imidazolium Ionic Liquid

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