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Wu, J. (2019). Improving the Lubricating Performance of Ionic Liquids for Different Contacts. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Improving the Lubricating Performance of Ionic Liquids for Different Contacts
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Förbättra smörjande prestanda av joniska vätskor för olika kontakter
Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2019
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-73628 (URN)978-91-7790-364-2 (ISBN)978-91-7790-365-9 (ISBN)
Public defence
2019-06-20, E231, Luleå, 09:00 (English)
Opponent
Supervisors
Available from: 2019-04-16 Created: 2019-04-12 Last updated: 2019-06-14Bibliographically approved
Wu, J., Mu, L., Feng, X., Lu, X., Larsson, R. & Shi, Y. (2019). Poly(alkylimidazolium bis(trifluoromethylsulfonyl) imide)-Based Polymerized Ionic Liquids: A Potential  High-Performance Lubricating Grease. Advanced Materials Interfaces, 6(5), Article ID 1801796.
Open this publication in new window or tab >>Poly(alkylimidazolium bis(trifluoromethylsulfonyl) imide)-Based Polymerized Ionic Liquids: A Potential  High-Performance Lubricating Grease
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2019 (English)In: Advanced Materials Interfaces, ISSN 2196-7350, Vol. 6, no 5, article id 1801796Article in journal (Refereed) Published
Abstract [en]

Polymers prepared from ionic liquids are widely called polymerized ionic liquids (PILs). Compared to monocationic and dicationic ILs, PILs have higher molecular weights, charge, and greater intermolecular interactions, which make PILs have a higher possibility to generate better lubricity. PILs of poly‐alkylimidazolium bis(trifluoromethylsulfonyl)imide (PImC6NTf2) is studied herein. Dicationic ILs of 1,1′‐(pentane‐1,5‐diyl)‐bis(3‐butylimidazolium) bis(trifluoromethylsulfonyl)imide (BIm5‐(NTf2)2) is used as additive to decrease the crystallization temperature of PImC6NTf2. Lubricity of PImC6NTf2 and PImC6NTf2+BIm5‐(NTf2)2, as well as BIm5‐(NTf2)2 for comparison is evaluated under severe conditions, i.e., 3.0 to 3.5 GPa and 200 °C. The rheological study suggests that PImC6NTf2 can be classified into grease. Tribological test results show that PImC6NTf2 has much better antiwear property than BIm5‐(NTf2)2, especially at 3.5 GPa. Adding 4% BIm5‐(NTf2)2 to PImC6NTf2 is able to reduce friction under high pressure. At 200 °C, PImC6NTf2 exhibits excellent lubricity. The mixture of 96%PImC6NTf2+4%BIm5‐(NTf2)2 shows even better antiwear property than neat PImC6NTf2 and exhibits the highest friction reducing property among the ILs at 200 °C. It is speculated that the robust strength of PILs and strong adhesion between PILs and solids are key factors in achieving the excellent antiwear property.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
grease, high pressure and high temperature, lubricity, polymerized ionic liquids
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-72623 (URN)10.1002/admi.201801796 (DOI)000460657100002 ()
Note

Validerad;2019;Nivå 2;2019-03-11 (johcin)

Available from: 2019-01-18 Created: 2019-01-18 Last updated: 2019-06-14Bibliographically approved
Mu, L., Wu, J., Matsakas, L., Chen, M., Rova, U., Christakopoulos, P., . . . Shi, Y. (2019). Two important factors of selecting lignin as efficient lubricating additives in poly (ethylene glycol): Hydrogen bond and molecular weight. International Journal of Biological Macromolecules, 129, 564-570
Open this publication in new window or tab >>Two important factors of selecting lignin as efficient lubricating additives in poly (ethylene glycol): Hydrogen bond and molecular weight
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2019 (English)In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 129, p. 564-570Article in journal (Refereed) Published
Abstract [en]

Lignin, one of the most abundant natural polymers, has been successfully used as an effective lubricant additive with high value. The chemical structure of lignin is very diverse and strongly affected by both the source of lignin (i.e. plant species) and the lignin extraction process. In this work, a series of lignin from different biomass sources (hard or soft wood) and extraction process (organosolv with or without acid catalyst) has been successfully incorporated into poly(ethylene glycol) (PEG) and fortified lubricating properties were achieved. The effects of different lignin on the rheological, thermal and tribological properties of the lignin/EG lubricants were systematically investigated by different characterization techniques. Lignin in PEG significantly improves the lubricating property, where a wear reduction of 93.8% was observed. The thermal and lubrication properties of the PEG lubricants filled with different kinds of lignin are tightly related to the synergistic state of hydrogen bonding and molecular weight distribution. Lignin with broader molecular weight distribution and higher hydroxyl content shows better adhesion on metal surfaces and strengthened lubricating film, which could be used as the efficient lubricating additives. This work provides a criterion for selecting appropriate lignin as the efficient lubricant additive and accelerates the application of lignin.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Lignin, Lubrication, Poly (ethylene glycol), Hydrogen bonding, Molecular weight
National Category
Bioprocess Technology Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements; Biochemical Process Engineering
Identifiers
urn:nbn:se:ltu:diva-72899 (URN)10.1016/j.ijbiomac.2019.01.175 (DOI)000466621200058 ()2-s2.0-85061540788 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-02-20 (svasva)

Available from: 2019-02-14 Created: 2019-02-14 Last updated: 2019-06-18Bibliographically approved
Wu, J., Huang, X., Berglund, K., Lu, X., Feng, X., Larsson, R. & Shi, Y. (2018). CuO nanosheets produced in graphene oxide solution: An excellent anti-wear additive for self-lubricating polymer composites. Composites Science And Technology, 162, 86-92
Open this publication in new window or tab >>CuO nanosheets produced in graphene oxide solution: An excellent anti-wear additive for self-lubricating polymer composites
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2018 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 162, p. 86-92Article in journal (Refereed) Published
Abstract [en]

In the present work, graphene oxide is used as template to produce CuO nanosheets, which solves aggregation and dispersion problems of CuO nanosheets resulting in improved lubricating performance. SEM and AFM studies show that CuO nanosheets are present in fusiform flake shape with a thickness, width and length of around 13, 400 and 1000 nm, respectively. CuO nanosheets were added to the carbon fibers reinforced Polytetrafluoroethylene (CF/PTFE) to study their lubricating performance. It is interesting, from fractured surfaces of composites, to find that CuO nanosheets enhance the interface properties between carbon fibers and PTFE. The wear resistance property of CF/PTFE is remarkably improved after filling CuO nanosheets. For example, the wear rate is reduced by 51% after filling 1.5 wt % CuO nanosheets. The wear resistance improvement effect of CuO nanosheets is much better than that of commercial CuO nanogranules and CuO nanorods. Worn surfaces and counter-surfaces studying indicates that CuO nanosheets can not only prevent the rubbed-off of PTFE or the detachment of CF, but also improve the properties of transfer films, which greatly reduce the adhesive wear and abrasive wear.

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-68387 (URN)10.1016/j.compscitech.2018.04.020 (DOI)000438180500010 ()2-s2.0-85046114065 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-05-09 (andbra)

Available from: 2018-04-17 Created: 2018-04-17 Last updated: 2018-08-09Bibliographically approved
Mu, L., Wu, J., Matsakas, L., Chen, M., Vahidi, A., Grahn, M., . . . Shi, Y. (2018). Lignin from Hardwood and Softwood Biomass as a Lubricating Additive to Ethylene Glycol. Molecules, 23(3), Article ID 537.
Open this publication in new window or tab >>Lignin from Hardwood and Softwood Biomass as a Lubricating Additive to Ethylene Glycol
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2018 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 23, no 3, article id 537Article in journal (Refereed) Published
Abstract [en]

Ethylene glycol (EG)-based lubricant was prepared with dissolved organosolv lignin from birch wood (BL) and softwood (SL) biomass. The effects of different lignin types on the rheological, thermal, and tribological properties of the lignin/EG lubricants were comprehensively investigated by various characterization techniques. Dissolving organosolv lignin in EG results in outstanding lubricating properties. Specifically, the wear volume of the disc by EG-44BL is only 8.9% of that lubricated by pure EG. The enhanced anti-wear property of the EG/lignin system could be attributed to the formation of a robust lubrication film and the strong adhesion of the lubricant on the contacting metal surface due to the presence of a dense hydrogen bonding (H-bonding) network. The lubricating performance of EG-BL outperforms EG-SL, which could be attributed to the denser H-bonding sites in BL and its broader molecular weight distribution. The disc wear loss of EG-44BL is only 45.7% of that lubricated by EG-44SL. Overall, H-bonding is the major contributor to the different tribological properties of BL and SL in EG-based lubricants.

Place, publisher, year, edition, pages
MDPI, 2018
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear) Bioprocess Technology Chemical Process Engineering
Research subject
Machine Elements; Biochemical Process Engineering; Chemical Technology
Identifiers
urn:nbn:se:ltu:diva-67800 (URN)10.3390/molecules23030537 (DOI)000428514100028 ()29495559 (PubMedID)2-s2.0-85043353975 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-03-01 (andbra)

Available from: 2018-03-01 Created: 2018-03-01 Last updated: 2019-04-02Bibliographically approved
Wu, J., Mu, L., Zhu, J., Feng, X., Lu, X., Larsson, R. & Shi, Y. (2018). Synthesis of hollow fullerene-like molybdenum disulfide/reduced graphene oxide nanocomposites with excellent lubricating properties. Carbon, 134, 423-430
Open this publication in new window or tab >>Synthesis of hollow fullerene-like molybdenum disulfide/reduced graphene oxide nanocomposites with excellent lubricating properties
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2018 (English)In: Carbon, ISSN 0008-6223, E-ISSN 1873-3891, Vol. 134, p. 423-430Article in journal (Refereed) Published
Abstract [en]

In this paper, bubble-on-plate structure is realized on hollow IF-MoS2/reduced graphene oxide (HIF-MoS2/RGO) nanocomposites. HIF-MoS2 nanocages templated with the generated ammonia (NH3) are connected to RGO through the interlayered MoS2. The as-prepared HIF-MoS2/RGO is added into an ionic grease to study the tribological behavior of HIF-MoS2/RGO. For comparison, commercial grade MoS2 nanoparticles, single RGO or HIF-MoS2 or their physical mixture are also studied. Tribological results show that, compared with other additives, HIF-MoS2/RGO nanocomposites have the best anti-wear properties especially under higher load of 3.0 GPa. The wear reduction of HIF-MoS2/RGO reinforced grease under 2.5 GPa and 3.0 GPa reached 67% and 96%, respectively. In addition, HIF-MoS2/RGO reinforced grease achieves much lower and stable friction coefficient (0.079, the value of neat grease is 0.098) under 3.0 GPa. HIF-MoS2/RGO reinforced grease maintains very low friction coefficient and wear up to 4.1 GPa, while the normal MoS2 and RGO show high wear at the pressure up to 3.0 GPa. It is proposed that HIF-MoS2 nanocages on RGO act as rolling balls during friction resulting in better separation of steels.

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-68256 (URN)10.1016/j.carbon.2018.04.021 (DOI)000433244900045 ()2-s2.0-85047407976 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-04-16 (andbra)

Available from: 2018-04-10 Created: 2018-04-10 Last updated: 2019-06-14Bibliographically approved
Huang, X., Wu, J., Zhu, Y., Zhang, Y., Feng, X. & Lu, X. (2017). Flow-resistance analysis of nano-confined fluids inspired from liquid nano-lubrication: A Review. Chinese Journal of Chemical Engineering, 25(11), 1552-1562
Open this publication in new window or tab >>Flow-resistance analysis of nano-confined fluids inspired from liquid nano-lubrication: A Review
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2017 (English)In: Chinese Journal of Chemical Engineering, ISSN 1004-9541, E-ISSN 2210-321X, Vol. 25, no 11, p. 1552-1562Article in journal (Refereed) Published
Abstract [en]

 How to reduce flow resistance of nano-confined fluids to achieve a high flux is a new challenge for modern chemical engineering applications, such as membrane separation and nanofluidic devices. Traditional models are inapplicable to explain the significant differences in the flow resistance of different liquid–solid systems. On the other hand, friction reduction in liquid nano-lubrication has received considerable attention during the past decades. Both fields are exposed to a common scientific issue regarding friction reduction during liquid–solid relative motion at nanoscale. A promising approach to control the flow resistance of nano-confined fluids is to reference the factors affecting liquid nano-lubrication. In this review, two concepts of the friction coefficient derived from fluid flow and tribology were discussed to reveal their intrinsic relations. Recent progress on low or ultra-low friction coefficients in liquid nano-lubrication was summarized based on two situations. Finally, a new strategy was introduced to study the friction coefficient based on analyzing the intermolecular interactions through an atomic force microscope (AFM), which is a cutting-point to build a new model to study flow-resistance at nanoscale.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-64730 (URN)10.1016/j.cjche.2017.05.005 (DOI)000417195600002 ()
Note

Validerad;2017;Nivå 2;2017-12-05 (andbra)

Available from: 2017-07-03 Created: 2017-07-03 Last updated: 2018-03-15Bibliographically approved
Huang, X., Wu, J., Lu, X., Feng, X. & Shi, Y. (2017). Tribological Properties of Porous PEEK Composites Containing Ionic Liquid under Dry Friction Condition. Lubricants, 5(2), Article ID 19.
Open this publication in new window or tab >>Tribological Properties of Porous PEEK Composites Containing Ionic Liquid under Dry Friction Condition
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2017 (English)In: Lubricants, ISSN 2075-4442, Vol. 5, no 2, article id 19Article in journal (Refereed) Published
Abstract [en]

NaCl particles were added into Polyetheretherketone (PEEK) and its composites to produce porous PEEK-based materials by washing NaCl away after the high-temperature compression molding process. After that, an ionic liquid was added into the porous materials under vacuum condition. Carbon fibers (CF), as reinforcement, and PTFE, as an internal solid lubricant, were employed to prepare PEEK composites. Tribological properties under dry friction condition were studied on a ring-on-disc tribo-meter. The influence of CF and PTFE on tribological properties was carefully investigated. The results indicated that, in comparison with traditional PEEK composites (CF/PTFE/PEEK), the porous PEEK composites containing ionic liquid showed much better tribological properties. It is found that CF can help PEEK form effective pores to suck in the ionic liquid resulting in a better tribological performance. CF reinforced porous PEEK containing ionic liquid (p-CF/PEEK + IL) demonstrated the lowest friction coefficient (27% of CF/PTFE/PEEK) and the lowest wear loss (only 0.9% of CF/PTFE/PEEK). Long time tribological test revealed that the wear mass loss comes from the running-in period, while its wear is negligible after this period. It is also found that the addition of PTFE has a negative influence on the tribological behaviors, especially under high sliding velocity and applied load

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-64637 (URN)10.3390/lubricants5020019 (DOI)000404637200011 ()2-s2.0-85029507063 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-06-29 (andbra)

Available from: 2017-06-29 Created: 2017-06-29 Last updated: 2018-11-26Bibliographically approved
Wu, J., Lu, X., Feng, X. & Shi, Y. (2016). Halogen-free ionic liquids as excellent lubricants for PEEK-stainless steel contacts at elevated temperatures (ed.). Tribology International, 104, 1-9
Open this publication in new window or tab >>Halogen-free ionic liquids as excellent lubricants for PEEK-stainless steel contacts at elevated temperatures
2016 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 104, p. 1-9Article in journal (Refereed) Published
Abstract [en]

Advanced polymers sliding against steel under ionic liquids (ILs) has great potential applications. However, halogen-containing ILs (h-ILs) often induce high corrosive wear to steel. In this work, halogen-free ILs (hf-ILs) were used as neat lubricants to investigate the performance of poly(ether-ether-ketone)-AISI304 stainless steel (PEEK-304ss) contacts at elevated temperatures. The results indicate that hf-ILs with short alkyl chains show excellent anti-corrosion and antiwear properties. The wear rates of 304ss lubricated by hf-ILs at 160 °C are 3–71% of those by h-ILs. The friction coefficients of PEEK-304ss lubricated by hf-ILs are just 13–33% of those by h-ILs. The excellent performance of hf-ILs can be attributed to the reason that hf-ILs will not generate any halogen containing acid during the test

National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-8837 (URN)10.1016/j.triboint.2016.08.009 (DOI)000386186500001 ()2-s2.0-84983559689 (Scopus ID)762d0d65-96ca-4441-b28a-dc9be5e96bac (Local ID)762d0d65-96ca-4441-b28a-dc9be5e96bac (Archive number)762d0d65-96ca-4441-b28a-dc9be5e96bac (OAI)
Note

Validerad; 2016; Nivå 2; 20160815 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2019-08-15Bibliographically approved
Wu, J., Zhu, J., Mu, L., Shi, Y., Dong, Y., Feng, X. & Lu, X. (2016). High load capacity with ionic liquid-lubricated tribological system. Tribology International, 94, 315-322
Open this publication in new window or tab >>High load capacity with ionic liquid-lubricated tribological system
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2016 (English)In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 94, p. 315-322Article in journal (Refereed) Published
Abstract [en]

Engineering polymers with high glass transition temperature have been widely used in dynamic friction systems by oil or solid lubrication. However, in high-load systems, oil lubrication is less efficient due to the viscosity decrease at higher temperatures induced by friction heat. [Bmim][PF6] ionic liquid was used and compared with traditional L-HM46 oil and solid PTFE. Taking advantage of high [Bmim][PF6] viscosity, strong steel-[Bmim][PF6] but poor PEEK-[Bmim][PF6] interaction, the [Bmim][PF6] lubricated PEEK/steel slide falls in hydrodynamic lubrication and elastohydrodynamic lubrication region under 150–1500N. While the oil and PTFE both failed to lubricate under 800N.

Keywords
Polymer, Friction and wear, Solid, Liquid
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-73913 (URN)10.1016/j.triboint.2015.08.022 (DOI)
Available from: 2019-05-13 Created: 2019-05-13 Last updated: 2019-06-14Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6137-5349

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