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Watanabe, Seiya
Publications (4 of 4) Show all publications
Kawada, S., Watanabe, S., Tadokoro, C. & Sasaki, S. (2018). Effects of Alkyl Chain Length of Sulfate and Phosphate Anion-Based Ionic Liquids on Tribochemical Reactions. Tribology letters, 66(1), Article ID 8.
Open this publication in new window or tab >>Effects of Alkyl Chain Length of Sulfate and Phosphate Anion-Based Ionic Liquids on Tribochemical Reactions
2018 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 66, no 1, article id 8Article in journal (Refereed) Published
Abstract [en]

Ionic liquids are expected to become increasingly popular lubricants as they feature a number of attractive properties. This investigation focused on sulfate and phosphate anion-based ionic liquids and the improvement in lubricating performance with the addition of these anions. However, the detailed lubricating mechanism and effect of alkyl chain length on tribochemical reactions are unclear. This study investigates tribochemical reaction processes using a quadrupole mass spectrometer (Q-MS) and X-ray photoelectron spectroscopy. Seven types of ionic liquids: 1-ethyl-3-methylimidazolium hydrogensulfate ([EMIM][HSO4]), 1-ethyl-3-methylimidazolium methylsulfate ([EMIM][MSU]), 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ESU]), 1-ethyl-3-methylimidazolium n-octylsulfate ([EMIM][OSU]), 1-ethyl-3-methylimidazolium dimethyl phosphate ([EMIM][DMP]), 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]), and 1-ethyl-3-methylimidazolium dibutyl phosphate ([EMIM][DBP]), were selected as lubricants. The friction coefficient of sulfate anion-based ionic liquids increased as their alkyl chain lengthened. However, wear scar diameter in this case showed the opposite tendency. The friction coefficient and wear scar diameter of phosphate anion-based ionic liquids increased with an increase in the alkyl chain length. Q-MS results indicated that the main outgassing components during sliding were the cation components, whereas the anion remained on the sliding surface and formed a tribofilm. The ionic liquids with short alkyl chains reacted with the sliding surface easily and led to very low friction. However, corrosive wear occurred in the case of the sulfate anion. On the other hand, anions with long alkyl chains underwent gradual tribochemical reactions because that led the mitigation of contact with nascent surface. The phosphate-based ionic liquids with long alkyl chains were unable to cause the lubricating effect due to low reactivity.

Place, publisher, year, edition, pages
Springer-Verlag New York, 2018
Keywords
Ionic liquids, Phosphate, Quadrupole mass spectrometer, Sulfate, Tribochemical reaction
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Identifiers
urn:nbn:se:kth:diva-220192 (URN)10.1007/s11249-017-0962-1 (DOI)000426475600024 ()2-s2.0-85037054268 (Scopus ID)
Note

QC 20171218

Available from: 2017-12-18 Created: 2017-12-18 Last updated: 2018-03-26Bibliographically approved
Kawada, S., Watanabe, S., Sasaki, S. & Miyatake, M. (2018). Evaluation of friction behavior and surface interactions of cyano-based ionic liquids under different sliding contacts and high vacuum condition. Lubricants, 6(3), Article ID 69.
Open this publication in new window or tab >>Evaluation of friction behavior and surface interactions of cyano-based ionic liquids under different sliding contacts and high vacuum condition
2018 (English)In: Lubricants, ISSN 2075-4442, Vol. 6, no 3, article id 69Article in journal (Refereed) Published
Abstract [en]

The friction coefficients of ionic liquids were evaluated by many investigations. Most investigations used fluorine-based ionic liquids as lubricants. However, these ionic liquids produce the corrosion wear. This investigation focuses on the use of cyano-based ionic liquids as lubricants. Compared to fluorine-based ionic liquids, cyano-based ionic liquids exhibit high friction coefficients against steel material. This work examines how the friction coefficients of cyano-based ionic liquids are influenced by the type of sliding material used (AISI 52100, TiO2, and tetrahedral amorphous carbon). TiO2 lubricated with 1-ethyl-3-methylimidazolium tricyanomethanide, and ta-C lubricated with 1-butyl-1methylpyrrolidinium tetracyanoborate exhibited very low friction coefficients, smaller than fluorine-based ionic liquids. Time-of-Flight Secondary Ion Mass Spectrometry analysis showed that anions adsorb onto the worn surface, suggesting that anion adsorption is a critical parameter influencing friction coefficients. Quadrupole Mass Spectrometry measurements revealed that cations decompose on the nascent surface, preventing adsorption on the worn surface. These results suggest that low friction coefficients require the decomposition of cations and adsorption of anions. The reactivity of nascent surface changes with the sliding material used due to varying catalytic activity of the nascent surfaces.

Place, publisher, year, edition, pages
MDPI AG, 2018
Keywords
Cyano-based ionic liquids, Quadrupolemass spectrometer, Tribo-chemical reaction, Vacuum
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-247197 (URN)10.3390/lubricants6030069 (DOI)000448335500013 ()2-s2.0-85056378000 (Scopus ID)
Note

QC 20190423

Available from: 2019-04-23 Created: 2019-04-23 Last updated: 2019-04-23Bibliographically approved
Kawada, S., Watanabe, S., Tadokoro, C., Tsuboi, R. & Sasaki, S. (2018). Lubricating mechanism of cyano-based ionic liquids on nascent steel surface. Tribology International, 119, 474-480
Open this publication in new window or tab >>Lubricating mechanism of cyano-based ionic liquids on nascent steel surface
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2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 119, p. 474-480Article in journal (Refereed) Published
Abstract [en]

This study investigates the lubricating mechanism of cyano-based ionic liquids on steel surfaces using Q-MS, ToF-SIMS, and TGA. [EMIM][DCN], [EMIM][TCC], [EMIM][TCB], [BMPL][DCN], [BMPL][TCC], and [BMPL][TCB] were selected as lubricants. [EMIM][TCB] exhibited the highest friction coefficient. The others exhibited very low friction coefficients of less than 0.08. Q-MS analysis indicated that the cation components were detected in outgassing during sliding tests. However, anion components were not detected. ToF-SIMS results showed that the anions remained on the worn surfaces which would lead low friction coefficients. To achieve low friction coefficient, the tribo-decomposition of the ionic liquids and adsorption of anion were required. TGA indicated thermal stability was an index for tribo-decomposition on the nascent steel surface.

Place, publisher, year, edition, pages
Elsevier Ltd, 2018
Keywords
Ionic liquids, Q-MS, TGA, ToF-SIMS, Ions, Liquids, Lubrication, Negative ions, Secondary ion mass spectrometry, Tribology, Friction coefficients, Low friction coefficients, Lubricating mechanism, Sliding test, Steel surface, ToF SIMS, Worn surface, Friction
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-223132 (URN)10.1016/j.triboint.2017.11.019 (DOI)000424960500045 ()2-s2.0-85034861265 (Scopus ID)
Note

Export Date: 13 February 2018; Article; CODEN: TRBIB; Correspondence Address: Kawada, S.; Graduate School of Tokyo University of Science, Department of Mechanical EngineeringJapan; email: 4515702@ed.tus.ac.jp; Funding details: 15J05958, JSPS, Japan Society for the Promotion of Science; Funding details: JP26630041; Funding details: JP16H02310. QC 20180327

Available from: 2018-03-27 Created: 2018-03-27 Last updated: 2018-03-27Bibliographically approved
Kawada, S., Sato, K., Watanabe, S. & Sasaki, S. (2017). Lubricating property of cyano-based ionic liquids against hard materials. Journal of Mechanical Science and Technology, 31(12), 5745-5750
Open this publication in new window or tab >>Lubricating property of cyano-based ionic liquids against hard materials
2017 (English)In: Journal of Mechanical Science and Technology, ISSN 1738-494X, E-ISSN 1976-3824, Vol. 31, no 12, p. 5745-5750Article in journal (Refereed) Published
Abstract [en]

Ionic liquids are expected to be used as a new lubricants and lubricant additives because of their unique properties. However, cyano-based ionic liquids have exhibited poor lubricating property with steel/steel contacts. We evaluated the lubricating properties of cyano-based ionic liquids with steel/hard materials contacts. TiO2, Al2O3, and tetrahedral amorphous carbon (ta-C) DLC were used as hard materials. Six types of ionic liquids, as combination of two types of cations ([EMIM], [BMPL]) and three types of cyanide anions ([DCN], [TCC] and [TCB]), were selected. In sliding tests of steel/TiO2 and steel/Al2O3 lubricated with [EMIM][DCN], [BMPL][DCN], [EMIM][TCC], [BMPL][TCC] exhibited low friction coefficients of less than 0.1. In addition, steel/Al2O3 and steel/ta-C DLC lubricated with [BMPL][TCB] exhibited very low friction coefficients less than 0.05. On the other hand, high friction coefficients were observed at steel/TiO2 and steel/Al2O3 contacts lubricated with [EMIM][TCB] and steel/ta-C DLC contact lubricated with [EMIM] cation group. Peeling of the ta-C DLC was observed when [EMIM] cation group was used. ToF-SIMS analysis indicated that the anion was adsorbed on the worn surfaces in the case of low frictional conditions. However, both ions were hardly observed in the case of high frictional conditions. It is considered that the ionic liquids underwent tribo-decomposition on the worn surfaces at low friction coefficient. To evaluate the degree of tribo-decomposition, Thermogravimetric analysis (TGA) was used. TGA results indicated that [EMIM][TCB], which exhibited high friction coefficient, had the most highest stability among all ionic liquids. Low stability ionic liquids, however, showed a tendency for low friction coefficient. These results suggest that lubricating properties are related to the stability of ionic liquids.

Place, publisher, year, edition, pages
KOREAN SOC MECHANICAL ENGINEERS, 2017
Keywords
Ceramics, DLC, Ionic liquids, TGA, ToF-SIMS, Vacuum
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-220843 (URN)10.1007/s12206-017-1116-y (DOI)000418144900016 ()2-s2.0-85038128980 (Scopus ID)
Note

QC 20180111

Available from: 2018-01-11 Created: 2018-01-11 Last updated: 2018-01-11Bibliographically approved
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