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A smart friction control strategy enabled by CO2 absorption and desorption
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.ORCID iD: 0000-0001-8157-4644
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.ORCID iD: 0000-0002-4271-0380
Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Chemical Engineering.ORCID iD: 0000-0002-4755-5754
Luleå University of Technology, Department of Engineering Sciences and Mathematics, Machine Elements.ORCID iD: 0000-0001-9110-2819
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2019 (English)In: Scientific Reports, E-ISSN 2045-2322, Vol. 9, no 1, article id 13262Article in journal (Refereed) Published
Abstract [en]

Intelligent control of friction is an attractive but challenging topic and it has rarely been investigated for full size engineering applications. In this work, it is instigated if it would be possible to adjust friction by controlling viscosity in a lubricated contact. By exploiting the ability to adjust the viscosity of the switchable ionic liquids, 1,8-Diazabicyclo (5.4.0) undec-7-ene (DBU)/ glycerol mixture via the addition of CO2, the friction could be controlled in the elastohydrodynamic lubrication (EHL) regime. The friction decreased with increasing the amount of CO2 to the lubricant and increased after partial releasing CO2. As CO2 was absorbed by the liquid, the viscosity of the liquid increased which resulted in that the film thickness increased. At the same time the pressure-viscosity coefficient decreased with the addition of CO2. When CO2 was released again the friction increased and it was thus possible to control friction by adding or removing CO2.

Place, publisher, year, edition, pages
Springer, 2019. Vol. 9, no 1, article id 13262
National Category
Chemical Process Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Chemical Technology; Machine Elements
Identifiers
URN: urn:nbn:se:ltu:diva-76046DOI: 10.1038/s41598-019-49864-wISI: 000485680900059PubMedID: 31519987Scopus ID: 2-s2.0-85072208170OAI: oai:DiVA.org:ltu-76046DiVA, id: diva2:1352250
Note

Validerad;2019;Nivå 2;2019-09-18 (johcin)

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2023-09-05Bibliographically approved
In thesis
1. Active friction control by using CO2 and moisture
Open this publication in new window or tab >>Active friction control by using CO2 and moisture
2019 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Nowadays the demand for intelligent control of tribological interactions is strongly increasing in various applications. We often strive to minimize friction but there are also many situations where high friction is desirable. In some cases, something in between, i.e. optimum friction, is attractive. Driven by the broad application prospects, many controllable friction systems regulated with external stimuli such as solvent, pH, temperature, electric potential, and magnetic field have been designed and fabricated. When external stimuli are imposed on the smart materials, the macroscopic physicochemical properties of the materials are dramatically changed, making controllable friction behavior to become possible. However, most of these exploratory works are in nano/micro size and it’s difficult to use these incredible methods in macroscale directly due to that macroscopic laws of friction do not generally apply to nanoscale contacts. This thesis attempts to find more versatile methods of friction control and try to find the possibility to achieve friction control at macro-size.

Firstly, since viscosity plays an important role in elastohydrodynamic lubrication (EHL) at macro-size, it is instigated if it would be possible to adjust friction by controlling viscosity in a lubricated contact. By exploiting the ability to adjust the viscosity of the switchable ionic liquids, 1,8-Diazabicyclo (5.4.0) undec-7-ene (DBU)/ glycerol mixture via the addition of CO2, the friction could be controlled in the EHL regime (Paper Ⅰ). In order to understand more about the lubricating mechanism of DBU/glycerol/CO2 mixture, the central film thickness of the lubricants as a function of the entrainment speed was investigated.

Secondly, due to that adhesion could have influence on boundary lubrication (BL) friction at macro-size, it is investigated if it would be possible to adjust friction in a lubricated contact by controlling environmental humidity, which can alter the H-bond types, leading the change of adhesion. By exploiting the ability to adjust the environmental humidity by various saturated salt solutions, friction behavior lubricated by Choline L-Proline ([Cho][Pro]) could be modulated in a wide range of relative humidities (RH) (Paper Ⅱ).

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2019
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
Keywords
friction control
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-76512 (URN)978-91-7790-488-5 (ISBN)978-91-7790-489-2 (ISBN)
Presentation
2019-12-05, E231, Luleå uninversity of technology, Luleå, 16:29 (English)
Opponent
Supervisors
Available from: 2019-10-28 Created: 2019-10-25 Last updated: 2019-11-06Bibliographically approved
2. Friction control in different lubrication regimes
Open this publication in new window or tab >>Friction control in different lubrication regimes
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

We often strive to minimize friction but there are also many situations where high friction is desirable. In some cases, something in between, i.e. optimum friction, is attractive. Driven by the broad application prospects, many controllable friction systems regulated with external stimuli such as solvent, pH, temperature, electric potential, and magnetic fields have been designed and fabricated. When external stimuli are imposed on the smart materials, the macroscopic physicochemical properties of the materials are dramatically changed, making controllable friction behavior to become possible. However, most of these exploratory works are in nano/micro size, which cannot be applied in macroscale for industry applications. 

Lubrication is mainly classified as three regimes: boundary, mixed and full film lubrication. If considering molecular size as well, there exists thin film lubrication between boundary lubrication and elastohydrodynamic lubrication, with the lubricating film thickness of a few nanometers to tens of nanometers. This thesis attempts to find more versatile methods of friction control and tries to find the possibility to achieve friction control at macroscale in all these lubrication regimes.

In this thesis, we investigated the possibility of adjusting friction by controlling viscosity in a lubricated contact and it was found that friction of switchable ionic liquids could be controlled in the EHL regime enabled by CO2 absorption and desorption in Paper 1. Glycerol solution formulated with ionic liquid was employed in Paper 2 to obtain superlubricity in thin film lubrication, and it was observed that the lubrication state could be switched between superlubricity and non-superlubricity by adjusting humidity. Friction control of multi-functional green lubricant in mixed lubrication was evaluated in Paper 3. Finally, the macroscopic friction control of ionic liquids in boundary lubrication enabled by environmental humidity was described in Paper 4, and stimuli responsive hydrogel also could be used for achieving friction control in boundary lubrication, studied in Paper 5.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2021
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
Keywords
friciton control, glycerol, lubrication regime
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-87593 (URN)978-91-7790-964-4 (ISBN)978-91-7790-965-1 (ISBN)
Public defence
2021-12-16, E231, Luleå, 09:00 (English)
Opponent
Supervisors
Available from: 2021-10-22 Created: 2021-10-21 Last updated: 2021-11-26Bibliographically approved

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Hua, JingBjörling, MarcusGrahn, MattiasLarsson, RolandShi, Yijun

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