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Publications (10 of 34) Show all publications
Nyberg, E., Tomastik, C., Dörr, N. & Minami, I. (2018). Boundary Film Formation of P-SiSO in Reduced Oxygen Atmosphere. In: NORDTRIB 2018: . Paper presented at 18th Nordic Symposium on Tribology – NORDTRIB 2018, Uppsala, 18-21 June 2018. Uppsala
Open this publication in new window or tab >>Boundary Film Formation of P-SiSO in Reduced Oxygen Atmosphere
2018 (English)In: NORDTRIB 2018, Uppsala, 2018Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Modern space exploration missions, such as planetary exploration of Mars, have significantly different tribological concerns compared to conditions faced by mechanical devices in satellites. Space lubricants have traditionally implied extremely low vapor pressure, but limited performance in boundary lubrication. Mars devices on the other hand are subjected to heavier loads, while operating in an atmosphere composed of CO2 at <1 kPa. Ionic liquids are synthetic fluids with inherently low vapor pressure that are known to readily form boundary films under severe conditions. In an effort to improve the tribological performance of ILs, hydrocarbon-mimicking ionic liquids have recently been designed. This recent work has displayed significantly improved lubrication performance for steel – steel tribo-systems in air, compared to PFPEs or fluorine-based ILs. Also, as a consequence of the hydrocarbon-mimicking structure, compatibility with several conventional tribo-improving additives have been displayed. In this work, we evaluate these novel fluids in a reduced oxygen environment under boundary lubricated conditions to evaluate the effect of oxygen supply on boundary film formation.

 

Place, publisher, year, edition, pages
Uppsala: , 2018
Keywords
Tribology, boundary film
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-70345 (URN)
Conference
18th Nordic Symposium on Tribology – NORDTRIB 2018, Uppsala, 18-21 June 2018
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-14Bibliographically approved
Rodríguez Ripoll, M., Totolin, V., Gabler, C., Bernardi, J. & Minami, I. (2018). Diallyl disulphide as natural organosulphur friction modifier via the in-situ tribo-chemical formation of tungsten disulphide. Applied Surface Science, 428, 659-668
Open this publication in new window or tab >>Diallyl disulphide as natural organosulphur friction modifier via the in-situ tribo-chemical formation of tungsten disulphide
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 428, p. 659-668Article in journal (Refereed) Published
Abstract [en]

The present work shows a novel method for generating in-situ low friction tribofilms containing tungsten disulphide in lubricated contacts using diallyl disulphide as sulphur precursor. The approach relies on the tribo-chemical interaction between the diallyl disulphide and a surface containing embedded sub-micrometer tungsten carbide particles. The results show that upon sliding contact between diallyl disulphide and the tungsten-containing surface, the coefficient of friction drops to values below 0.05 after an induction period. The reason for the reduction in friction is due to tribo-chemical reactions that leads to the in-situ formation of a complex tribofilm that contains iron and tungsten components. X-ray photoelectron spectroscopy analyses indicate the presence of tungsten disulphide at the contact interface, thus justifying the low coefficient of friction achieved during the sliding experiments. It was proven that the low friction tribofilms can only be formed by the coexistence of tungsten and sulphur species, thus highlighting the synergy between diallyl disulphide and the tungsten-containing surface. The concept of functionalizing surfaces to react with specific additives opens up a wide range of possibilities, which allows tuning on-site surfaces to target additive interactions.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-65702 (URN)10.1016/j.apsusc.2017.09.100 (DOI)000415227000082 ()
Note

Validerad;2017;Nivå 2;2017-10-04 (andbra)

Available from: 2017-09-18 Created: 2017-09-18 Last updated: 2018-01-13Bibliographically approved
Nyberg, E., Tomastik, C., Dörr, N. & Minami, I. (2018). Influence of atmosphere on boundary film formation from ionic liquids. In: : . Paper presented at 73rd STLE Annual Meeting & Exhibition, Minneapolis, Minnesota, May 20-24 2018. Minneapolis, MN
Open this publication in new window or tab >>Influence of atmosphere on boundary film formation from ionic liquids
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Modern space exploration missions, such as planetary exploration of Mars, have significantly different tribological concerns compared to conditions faced by mechanical devices in satellites. Space lubricants have traditionally implied extremely low vapor pressure, but limited performance in boundary lubrication. Mars devices on the other hand are subjected to heavier loads, while operating in an atmosphere composed of CO2 at <1 kPa. Ionic liquids are synthetic fluids with inherently low vapor pressure that are known to readily form boundary films under severe conditions. In our recent work, an ionic liquid designed as lubricant base fluid formed highly effective boundary films composed of silicate when evaluated in air. These boundary films include oxygen, which can possibly be supplied by the atmosphere or by the lubricant itself. In this work, we employ tribotesting in CO2, and N2, and perform surface analysis to evaluate the effect of oxygen supply on boundary film formation. 

Place, publisher, year, edition, pages
Minneapolis, MN: , 2018
Keywords
Tribology, ionic liquids, boundary film, atmosphere
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-70343 (URN)
Conference
73rd STLE Annual Meeting & Exhibition, Minneapolis, Minnesota, May 20-24 2018
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-14Bibliographically approved
Hansen, J., Björling, M., Minami, I. & Larsson, R. (2018). Performance and mechanisms of silicate tribofilm in heavily loaded rolling/sliding non-conformal contacts. Tribology International, 123, 130-141
Open this publication in new window or tab >>Performance and mechanisms of silicate tribofilm in heavily loaded rolling/sliding non-conformal contacts
2018 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 123, p. 130-141Article in journal (Refereed) Published
Abstract [en]

Lubricant performance is vital as heavy-duty gear manufacturers increase power density in their efforts towards increased efficiency. In this work, a recently developed ionic liquid is introduced as a multifunction additive for use in hydrocarbon base fluid. A ball-on-disc tribological test machine was used to evaluate friction and wear in heavily loaded mixed rolling/sliding conditions. The novel multifunctional additive is benchmarked against conventional axle-gear oil additives, and results shows excellent tribological performance in terms of friction and wear. Post-test surface analysis of the wear scars revealed a silicate based tribofilm derived from the novel ionic additive, contrary to conventional phosphorous and/or sulfur based. The silicate tribofilm is correlated to a significantly increased wear resistance and vastly improved running-in performance.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-67928 (URN)10.1016/j.triboint.2018.03.006 (DOI)000431161600014 ()2-s2.0-85043594654 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-03-20 (andbra)

Available from: 2018-03-14 Created: 2018-03-14 Last updated: 2018-06-11Bibliographically approved
Nyberg, E., Grahn, M. & Minami, I. (2017). Additives to Improve Tribological Properties of Ionic Liquid as Base Fluids. In: : . Paper presented at 72nd STLE Annual Meeting & Exhibition, Atlanta, GA, May 21-25 2017. Atlanta, GA
Open this publication in new window or tab >>Additives to Improve Tribological Properties of Ionic Liquid as Base Fluids
2017 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Room temperature ionic liquids (RTILs) have several properties which make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome these drawbacks, hydrocarbon-imitating RTIL base fluids have recently been developed. These lubricants aim for a more balanced interaction with metal surfaces while enabling compatibility with common additives, so that the reactivity with the lubricated surface can be tuned in a manner similar to hydrocarbon base oil–additive systems. In this work, the effects of several common additives in the novel RTIL were examined by laboratory tribotesting. Surface analysis was performed in order to study the lubrication mechanisms.

Place, publisher, year, edition, pages
Atlanta, GA: , 2017
Keywords
Tribology, ionic liquids, friction, wear, performance additive
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Chemical Process Engineering
Research subject
Machine Elements; Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-70341 (URN)
Conference
72nd STLE Annual Meeting & Exhibition, Atlanta, GA, May 21-25 2017
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-14Bibliographically approved
Nyberg, E. & Minami, I. (2017). Boundary Film Formation from Hydrocarbon-mimicking Ionic Liquids. In: : . Paper presented at ÖTG Symposium 2017, Tribologie in Industrie und Forschung, Neue Aufgaben – innovative Lösungen, Wiener Neustadt, Austria, 22/11 2017. Wiener Neustadt, Austria
Open this publication in new window or tab >>Boundary Film Formation from Hydrocarbon-mimicking Ionic Liquids
2017 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Ionic liquids have properties that are very useful in high performance lubricants. However, they must be well tuned to the tribological system. Hydrocarbon-mimicking ionic liquids have been developed in an effort to overcome some of the compatibility problems that are holding back the use of ionic liquids in tribology. In this work, hydrocarbon-mimicking ionic liquids are evaluated as base fluids in steel-steel reciprocating tribotests. Wear and friction reducing boundary films are formed and found to be composed mainly of Si and O. An amine additive is found to stimulate the formation of this boundary film.

Place, publisher, year, edition, pages
Wiener Neustadt, Austria: , 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-70342 (URN)
Conference
ÖTG Symposium 2017, Tribologie in Industrie und Forschung, Neue Aufgaben – innovative Lösungen, Wiener Neustadt, Austria, 22/11 2017
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-14Bibliographically approved
Nyberg, E., Mouzon, J., Grahn, M. & Minami, I. (2017). Formation of Boundary Film from Ionic Liquids Enhanced by Additives. Applied Sciences, 7(5), Article ID 433.
Open this publication in new window or tab >>Formation of Boundary Film from Ionic Liquids Enhanced by Additives
2017 (English)In: Applied Sciences, E-ISSN 2076-3417, Vol. 7, no 5, article id 433Article in journal (Refereed) Published
Abstract [en]

Room temperature ionic liquids (RTILs) have several properties that make them interesting candidates as base fluids for extreme conditions. However, a lack of compatibility with tribo-improving additives combined with an often overly aggressive nature is limiting their use as base fluids. To overcome these drawbacks, hydrocarbon-imitating RTIL base fluids have recently been developed. In this study, the effects of several common additives in the novel RTIL (P-SiSO) were examined by laboratory tribotesting. A reciprocating steel-steel ball-on-flat setup in an air atmosphere was used, where the lubricant performance was evaluated over a range of loads and temperatures. Surface analyses after testing were carried out using optical profilometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). Neat P-SiSO displayed high performance in the tribotests. At an elevated load and temperature, a shift in lubrication mode was observed with an accompanying increase in friction and wear. Surface analysis revealed a boundary film rich in Si and O in the primary lubrication mode, while P was detected after a shift to the secondary lubrication mode. An amine additive was effective in reducing wear and friction under harsh conditions. The amine was determined to increase formation of the protective Si–O film, presumably by enhancing the anion activity.

Place, publisher, year, edition, pages
Basel: MDPI, 2017
Keywords
gränsskiktssmörjning, jonvätska, friktion, nötning, tribologi
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Chemical Process Engineering
Research subject
Machine Elements; Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-63211 (URN)10.3390/app7050433 (DOI)000404449000002 ()2-s2.0-85018920929 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-05-10 (rokbeg)

Available from: 2017-05-02 Created: 2017-05-02 Last updated: 2018-11-26Bibliographically approved
Rodríguez Ripoll, M., Totolin, V., Bedolla, P. O. & Minami, I. (2017). Methionine as a Friction Modifier for Tungsten Carbide-Functionalized Surfaces via in Situ Tribo-Chemical Reactions. ACS Sustainable Chemistry & Engineering, 5(8), 7030-7039
Open this publication in new window or tab >>Methionine as a Friction Modifier for Tungsten Carbide-Functionalized Surfaces via in Situ Tribo-Chemical Reactions
2017 (English)In: ACS Sustainable Chemistry & Engineering, E-ISSN 2168-0485, Vol. 5, no 8, p. 7030-7039Article in journal (Refereed) Published
Abstract [en]

This work presents a novel method for generating in-situ low friction tribofilms in lubricated contacts using α-amino acid L-methionine as additive. Methionine is an environmentally acceptable natural organosulphur compound that is typically used in food industry. Our approach relies in the use of steel surfaces functionalized with tungsten carbide particles that are tailored to interact with methionine via a tribo-chemical reaction. The results show that after an induction period, the friction drops dramatically by 60% down to values of 0.06 when methionine was used as additive in lubricated tungsten carbide functionalized surfaces. The low friction could only be achieved by the coexistence of tungsten from the functionalized surfaces and sulphur from methionine, which led to the presence of tribo-chemically generated tribofilms. Ab-initio simulations indicate that the tribo-chemical reaction for forming tungsten disulphide is energetically favourable, thus attributing the observed friction reduction mechanism to the in-situ formation of this compound during the sliding process. The concept of functionalizing surfaces to react with specific additives opens up a wide range of possibilities, which allows tuning surfaces to target specific additive interactions. This synergy can be exploited for using novel green additive technology, thus allowing more environmentally friendly formulations with outstanding tribological performance.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-64475 (URN)10.1021/acssuschemeng.7b01258 (DOI)000407410900074 ()2-s2.0-85027234251 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-08-09 (rokbeg)

Available from: 2017-06-26 Created: 2017-06-26 Last updated: 2018-07-10Bibliographically approved
Nyberg, E., Respatiningsih, C. & Minami, I. (2017). Molecular design of advanced lubricant base fluids: hydrocarbon-mimicking ionic liquids. RSC Advances, 7(11), 6364-6373
Open this publication in new window or tab >>Molecular design of advanced lubricant base fluids: hydrocarbon-mimicking ionic liquids
2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 11, p. 6364-6373Article in journal (Refereed) Published
Abstract [en]

This paper describes the molecular design and tribological evaluation of novel room-temperature ionic liquid (RTIL) lubricants{,} abbreviated as P-SiSOs. The RTILs are designed to mimic hydrocarbons{,} in order to ensure their compatibility with existing tribosystems as well as enable use of conventional additives. Steel-on-steel ball-on-flat reciprocating tribotests performed under atmospheric conditions show that the neat P-SiSOs exhibit favorable performances{,} resulting in friction and wear significantly lower than those in the case of the perfluoropolyether lubricants used as references. Tribotests performed at elevated loads and temperatures indicate the formation of friction-reducing boundary films of the neat P-SiSOs. The tribological performance of the P-SiSO is improved further by the incorporation of additives conventionally used in hydrocarbon oils. When used in a concentration of 5 wt%{,} the additives glycerol monooleate{,} dibenzyl disulfide{,} and oleylamine improve the tribological characteristics of P-SiSO. These results indicate that molecular-designed hydrocarbon-mimicking RTIL lubricants can exhibit suitable performances in the neat form and that their performances can be improved further by using conventional additives{,} as in the case of hydrocarbon base oil-additive systems.

Place, publisher, year, edition, pages
RSC Publishing, 2017
Keywords
additive compatibility, synthetic lubricant, friction modification, wear prevention, tetraalkylphosphonium, RTIL
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-61571 (URN)10.1039/C6RA27065D (DOI)000393755100024 ()2-s2.0-85010341504 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-02-07 (andbra)

Available from: 2017-01-21 Created: 2017-01-21 Last updated: 2018-12-14Bibliographically approved
Minami, I. (2017). Molecular science of lubricant additives. Applied Sciences, 7(5), Article ID 445.
Open this publication in new window or tab >>Molecular science of lubricant additives
2017 (English)In: Applied Sciences, E-ISSN 2076-3417, Vol. 7, no 5, article id 445Article in journal (Refereed) Published
Abstract [en]

This review aims at introducing an engineering field of lubrication to researchers who are not familiar with tribology, thereby emphasizing the importance of lubricant chemistry in applied science. It provides initial guidance regarding additive chemistry in lubrication systems for researchers with different backgrounds. The readers will be introduced to molecular sciences underlying lubrication engineering. Currently, lubricant chemistry, especially "additive technology", looks like a very complicated field. It seems that scientific information is not always shared by researchers. The cause of this is that lubrication engineering is based on empirical methods and focuses on market requirements. In this regard, engineering knowhow is held by individuals and is not being disclosed to scientific communities. Under these circumstances, a bird's-eye view of lubricant chemistry in scientific words is necessary. The novelty of this review is to concisely explain the whole picture of additive technology in chemical terms. The roles and functions of additives as the leading actors in lubrication systems are highlighted within the scope of molecular science. First, I give an overview of the fundamental lubrication model and the role of lubricants in machine operations. The existing additives are categorized by the role and work mechanism in lubrication system. Examples of additives are shown with representative molecular structure. The second half of this review explains the scientific background of the lubrication engineering. It includes interactions of different components in lubrication systems. Finally, this review predicts the technical trends in lubricant chemistry and requirements in molecular science. This review does not aim to be a comprehensive chart or present manufacturing knowhow in lubrication engineering. References were carefully selected and cited to extract "the most common opinion" in lubricant chemistry and therefore many engineering articles were omitted for conciseness

Place, publisher, year, edition, pages
Basel: MDPI, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-63546 (URN)10.3390/app7050445 (DOI)000404449000013 ()2-s2.0-85019090842 (Scopus ID)
Note

Validerad; 2017; Nivå 2; 2017-05-26 (andbra)

Available from: 2017-05-26 Created: 2017-05-26 Last updated: 2018-11-26Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-8972-2944

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