Change search
Link to record
Permanent link

Direct link
BETA
Alternative names
Publications (10 of 58) Show all publications
Wang, H., Liu, Y., Guo, F., Sheng, H., Xia, K., Liu, W., . . . Luo, J. (2020). Catalytically Active Oil-based Lubricant Additives Enabled by Calcining Ni-Al Layered Double Hydroxides. Journal of Physical Chemistry Letters, 11, 113-120
Open this publication in new window or tab >>Catalytically Active Oil-based Lubricant Additives Enabled by Calcining Ni-Al Layered Double Hydroxides
Show others...
2020 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 11, p. 113-120Article in journal (Refereed) Published
Abstract [en]

Layered double hydroxides (LDHs) have lately been hailed as robust lubricant additives for improving tribological properties and as ideal catalysts for synthesizing carbon-based nanomaterials. In this paper, in situ analytical tools are used to track the evolution of the crystal structure and chemical composition of LDHs during calcination. Nickel oxide and elemental nickel can be produced by calcining NiAl-LDH in air (LDH-C-Air) and argon (LDH-C-Ar), respectively. For the base oil with 1 wt % LDH-C-Air, negligible wear can be detected even after a 2 h friction test under a severe contact pressure (∼637 MPa). A relatively thick tribofilm (∼60 nm) with a better mechanical property is formed, which protects the solid surface from severe wear. In addition, the possible formed carbon debris may also prevent the direct collision of asperities and effectively improve the wear resistance. This work provides a unique vision for the application of calcined LDHs with the combination of catalysis and tribology.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2020
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-77248 (URN)10.1021/acs.jpclett.9b03094 (DOI)
Note

Validerad;2020;Nivå 2;2019-12-23 (svasva)

Available from: 2019-12-23 Created: 2019-12-23 Last updated: 2019-12-23Bibliographically approved
Hua, J., Björling, M., Larsson, R. & Shi, Y. (2020). Controllable Friction of Green Ionic Liquids via Environmental Humidity. Advanced Engineering Materials
Open this publication in new window or tab >>Controllable Friction of Green Ionic Liquids via Environmental Humidity
2020 (English)In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648Article in journal (Refereed) Epub ahead of print
Abstract [en]

Intelligent control of friction is an attractive but challenging topic. In this work, it is investigated if it would be possible to adjust friction in a lubricated contact by controlling environmental humidity. By exploiting the ability to adjust the environmental humidity by various saturated salt solutions, friction behavior of contacts lubricated with Choline l‐Proline ([Cho][Pro]) is modulated in a wide range of relative humidity (RH). The friction increases when the environmental humidity is increased and decreases when water is partially evaporated to a lower RH. It is thus possible to control friction by environmental humidity. The addition of water in ionic liquids (ILs) causes a decrease in viscosity, but as the tests are calculated to be performed in boundary lubrication the viscosity change is not the main factor for the change in friction. The friction sensitivity of RH can be explained by the effect of adhesion on the water uptake from humid air by [Cho][Pro]. Furthermore, the reversible changes of H‐bond types determined by the water content could be another explanation to the altered friction.

Place, publisher, year, edition, pages
John Wiley & Sons, 2020
Keywords
friction control, humidity, ionic liquids, viscosity
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-77681 (URN)10.1002/adem.201901253 (DOI)
Funder
Swedish Research Council Formas, 2016-01098Swedish Research Council, 2017-04914Swedish Energy Agency, 2018-003910
Available from: 2020-02-10 Created: 2020-02-10 Last updated: 2020-02-17
Fisher, T. R., Zhou, G., Shi, Y. & Huang, L. (2020). How does hydrogen bond network analysis reveal the golden ratio of water–glycerol mixtures?. Physical Chemistry, Chemical Physics - PCCP, 22(5), 2887-2907
Open this publication in new window or tab >>How does hydrogen bond network analysis reveal the golden ratio of water–glycerol mixtures?
2020 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 22, no 5, p. 2887-2907Article in journal (Refereed) Published
Abstract [en]

Properties of water–glycerol mixtures depend closely on the water/glycerol ratio. Around the 30 mol% glycerol concentration mark, the so-called golden ratio of water–glycerol mixtures, several of the mixture's properties have observed maxima or minima, without a clear fundamental explanation. In this work, a series of molecular dynamics simulations have been performed over a wide range of water–glycerol concentrations to analyze the intermolecular hydrogen bond (H-bond) network. The collected values from simulations are justified from both a probabilistic model of H-bonding and from observing the dynamic behavior of each type of H-bonds. The populations of H-bonds that exist at a given concentration of glycerol are largely governed by the probability of one oxygen atom randomly associating with another oxygen atom. However, the H-bonds that glycerol oxygen can form are dependent on the H-bonds that are formed by the other intramolecular glycerol oxygen. Based on the dynamic analysis of each type of H-bonds, there are deviations from randomly associating with another oxygen. Water preferentially donates a hydrogen to a glycerol than to another water molecule. Yet, glycerol has a near-equal likelihood for donating a hydrogen to either another glycerol or a water. This has an effect of increasing the number of H-bonds between water and glycerol molecules and decreasing H-bonds between two water molecules. A maximum contribution of H-bonds between water and glycerol occurs around 30 mol% glycerol which is a concentration where several of the mixture's properties have an observed maxima or minima.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2020
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-77772 (URN)10.1039/C9CP06246G (DOI)31950122 (PubMedID)
Note

Validerad;2020;Nivå 2;2020-02-19 (johcin)

Available from: 2020-02-19 Created: 2020-02-19 Last updated: 2020-02-19Bibliographically approved
Xi, Y., Hua, J. & Shi, Y. (2020). Noncontact Triboelectric Nanogenerator for Human Motion Monitoring and Energy Harvesting. Nano Energy, 69, Article ID 104390.
Open this publication in new window or tab >>Noncontact Triboelectric Nanogenerator for Human Motion Monitoring and Energy Harvesting
2020 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 69, article id 104390Article in journal (Refereed) Published
Abstract [en]

Monitoring human motion and harvesting its energy is an interesting and important topic. Triboelectric nanogenerators (TENGs) have shown their potential for signal detecting and energy harvesting. In this paper, a noncontact paper-based TENG is creatively proposed to be used as a self-powered human motion monitoring sensor and also to be used for human motion energy harvesting. The noncontact mode avoids the requirement of direct physical contact between the TENG and the human subject, which fascinates the application of TENG and can increase its service life. It is found that the walking gait cycle (leg raising and falling), moving direction, walking or running speed and moving path can be reflected by the output voltage signals directly and clearly. Noncontact human motion energy harvesting is also achieved by using this TENG with a rectification circuit. It is also surprisingly found that this TENG is able to detect human motion even through a building wall, and the output voltage is strong enough to be captured by a normal multimeter without any additional amplification circuit. This study opens up a new method for self-powered noncontact human movement detecting and monitoring.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
noncontact, self-powered, human motion monitoring, triboelectric nanogenerator, energy harvesting
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-77218 (URN)10.1016/j.nanoen.2019.104390 (DOI)
Note

Validerad;2020;Nivå 2;2020-01-27 (johcin)

Available from: 2019-12-18 Created: 2019-12-18 Last updated: 2020-01-27Bibliographically approved
Ma, X., Lan, X., Wu, L., Wang, L., Gu, Q., Shi, Y., . . . Luo, Z. (2020). Photo-induced Actuator using Temperature and Light Dual Responsive Azobenzene Containing Ion Gel in Ionic Liquid. European Polymer Journal, 123, Article ID 109446.
Open this publication in new window or tab >>Photo-induced Actuator using Temperature and Light Dual Responsive Azobenzene Containing Ion Gel in Ionic Liquid
Show others...
2020 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 123, article id 109446Article in journal (Refereed) Published
Abstract [en]

A series of well-defined random copolymers comprising butyl acrylate (BA) and 4-phenylazophenylmethacrylate (AzoMA) (P(AzoMA-r-BA)) are prepared successfully by reversible addition fragmentation chain transfer (RAFT) polymerization. P(AzoMA-r-BA)s show LCST-type phase transition in 1-butyl-3-methylimidazolium bis(trifluoromethanesulfone)amide ([C4mim][NTf2]). LCST depends on the photoisomerization state of azobenzene, as well as on the AzoMA composition in the random copolymers. LCST of (P(cis-AzoMA-r-BA) is significantly higher than that of P(trans-AzoMA-r-BA), because cis-AzoMA and trans-AzoMA behave as solvato-philic and solvato-phobic comonomer, respectively. At a bistable temperature, photo-induced phase separation is completely reversible. Secondly, based on this phenomenon, a thermo- / photo- responsive ion gel (BA-AzoMA ion gel) can be prepared by free radical polymerization of BA and AzoMA using ethylene glycol dimethacrylate (EGDMA) as crosslinker in [C4mim][NTf2]. BA-AzoMA ion gel shows high temperature contraction and low temperature expansion behavior, due to LCST-type phase behavior of polymer system consisting of AzoMA and BA. Contraction temperature of BA-AzoMA ion gel depends on photoisomerization state of the azobenzene group in polymers. At a bistable temperature, photo-induced expansion-contraction is reversible. Finally, a Photo-induced actuator can be realized using BA-AzoMA ion gel at suitable temperatures, featuring reversible bending by alternate irradiating with visible and UV light. The bending behavior is also demonstrated.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
ionic liquid, ion gel, actuator, azobenzene, LCST
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-77247 (URN)10.1016/j.eurpolymj.2019.109446 (DOI)
Note

Validerad;2020;Nivå 2;2020-01-13 (johcin)

Available from: 2019-12-23 Created: 2019-12-23 Last updated: 2020-01-13Bibliographically approved
Shetty, P., Mu, L. & Shi, Y. (2020). Polyelectrolyte Cellulose Gel with PEG/Water: Toward Fully Green Lubricating Grease. Carbohydrate Polymers, 230, Article ID 115670.
Open this publication in new window or tab >>Polyelectrolyte Cellulose Gel with PEG/Water: Toward Fully Green Lubricating Grease
2020 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 230, article id 115670Article in journal (Refereed) Published
Abstract [en]

Developing a fully green lubricant is an urgent need due to the growing consciousness of environmental protection and dwindling resources. In this work, fully green gel lubricants were developed out of cellulose derivatives as gelator and mixture of water and poly(ethylene glycol) 200 (PEG 200) as the base fluid. The non-ionic hydroxyethyl cellulose (HEC) and anionic sodium carboxymethyl cellulose (NaCMC) were chosen to understand the effect of ionic and non-ionic gelators on the thermal, rheological and the tribological properties of the gel lubricant. HEC or NaCMC is demonstrated as effective additive to reduce wear, stabilize friction coefficient and enhance the thermal stability of developed lubricants. It is shown that anionic gelator will result in producing lower friction and wear in comparison to non-ionic gelator, which may be attributed to the possible tribo-film formation due to the negative charge in the NaCMC molecules and its larger molecular weight.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Cellulose, Green, lubricant, PEG/Water, Gel
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-76921 (URN)10.1016/j.carbpol.2019.115670 (DOI)000504402300109 ()2-s2.0-85075898313 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-01-13 (johcin)

Available from: 2019-11-28 Created: 2019-11-28 Last updated: 2020-01-13Bibliographically approved
Shao, J., Willatzen, M., Shi, Y. & Wang, Z. L. (2019). 3D mathematical model of contact-separation and single-electrode mode triboelectric nanogenerators. Nano Energy, 60, 630-640
Open this publication in new window or tab >>3D mathematical model of contact-separation and single-electrode mode triboelectric nanogenerators
2019 (English)In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 60, p. 630-640Article in journal (Refereed) Published
Abstract [en]

Based on a set of finite-sized charged planes (FSCP), a simple time-dependent three-dimensional spatial model for the electric potential and electric field in an inhomogeneous medium composed of dielectric materials and metal contacts is proposed and used to assert triboelectric nanogenerator operation. Solving the problem of FSCP makes the three-dimensional spatial model relevant for practical TENG applications and allow for accurate and reliable results. Connecting the metal contacts to an electric resistance, Kirchhoff's law is used to derive a first-order time-dependent differential equation for the mobile charges on the metal contacts and the displacement current. Specially, the displacement current (Maxwell's displacement current) in a TENG equals to the conduction current in the external circuit is obtained. We then consider two important types of triboelectric nanogenerators: the contact-separation (CS) mode and the single-electrode (SEC) mode. A forced movement of the dielectric materials and/or the metal contacts leads to currents flowing in the system and a time-varying electrical potential, and therefore the generation of electrical power. Then, new and more accurate capacitance equations for CS and SEC modes of TENGs are extracted. Several examples of energy harvesting scenarios are finally analyzed.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
triboelectric nanogenerator, 3D mathematical model, Displacement current, Contact-mode, Single-electrode mode
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-73336 (URN)10.1016/j.nanoen.2019.03.072 (DOI)000467774100069 ()2-s2.0-85063899114 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-04-12 (johcin)

Available from: 2019-03-28 Created: 2019-03-28 Last updated: 2019-06-18Bibliographically approved
Chen, J., Li, F., Luo, Y., Shi, Y., Ma, X., Zhang, M., . . . Luo, Z. (2019). A self-healing elastomer based on an intrinsic non-covalent cross-linking mechanism. Journal of Materials Chemistry A, 7(25), 15207-15214
Open this publication in new window or tab >>A self-healing elastomer based on an intrinsic non-covalent cross-linking mechanism
Show others...
2019 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 7, no 25, p. 15207-15214Article in journal (Refereed) Published
Abstract [en]

Synthesis and comprehensive examination of a polyurethane (urea) elastomer that self-heals based on intrinsic dynamic non-covalent bonds (van der Waals and hydrogen) are reported. The dynamic non-covalent bonds include hydrogen bonds and van der Waals forces. The difference in the previous approach in which hydrogen bond self-healing materials introduced dense quadruple hydrogen bonds at the ends or branched chains poly(propylene carbonate) (PPC) diol was used as the soft segment of the polyurethane (urea) material, and strong van der Waals forces were provided by the large number of carbonyl groups in its main chain; hydrogen bonds were formed by urethane bonds, urea bonds, and the carbonyl groups on PPC. The mechanical properties and healing efficiency of the self-healing polyurethane (urea) elastomer were studied. In situtemperature-dependent infrared and low-field nuclear magnetic resonance (LNMR) measurements were combined with molecular dynamics simulations to investigate the self-healing mechanisms. The results of the studies on the self-healing polyurethane demonstrate that the dynamic cross-linking between hydrogen bonds and van der Waals forces is the basic driving force for the self-healing ability of the material, and temperature is the key factor that affects hydrogen bonding and van der Waals forces. The effect of crystallization on the self-healing ability of the material was also studied. The molecular dynamics simulation results also demonstrate interplay between van der Waals forces and hydrogen bonds at different temperatures.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2019
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-74367 (URN)10.1039/C9TA03775F (DOI)000473054500023 ()2-s2.0-85068172124 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-07-12 (johcin)

Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2019-07-12Bibliographically approved
Hua, J., Björling, M., Grahn, M., Larsson, R. & Shi, Y. (2019). A smart friction control strategy enabled by CO2 absorption and desorption. Scientific Reports, 9(1), Article ID 13262.
Open this publication in new window or tab >>A smart friction control strategy enabled by CO2 absorption and desorption
Show others...
2019 (English)In: Scientific Reports, ISSN 2045-2322, 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
National Category
Chemical Process Engineering Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Chemical Technology; Machine Elements
Identifiers
urn:nbn:se:ltu:diva-76046 (URN)10.1038/s41598-019-49864-w (DOI)000485680900059 ()31519987 (PubMedID)2-s2.0-85072208170 (Scopus ID)
Note

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

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2019-10-25Bibliographically approved
Björling, M. & Shi, Y. (2019). DLC and Glycerol: Superlubricity in Rolling/Sliding Elastohydrodynamic Lubrication. Tribology letters, 67(1), Article ID 23.
Open this publication in new window or tab >>DLC and Glycerol: Superlubricity in Rolling/Sliding Elastohydrodynamic Lubrication
2019 (English)In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 67, no 1, article id 23Article in journal (Refereed) Published
Abstract [en]

Low friction is one of the most important parameters for the development of machine components and machines with high efficiency. Many of the common machine components of today such as gears, rolling element bearings and cam-followers are defined by their non-conformal contacts leading to high-contact pressures, typically 1–4 GPa. The lubrication of such contacts is usually called elastohydrodynamic lubrication (EHL). Diamond-like carbon (DLC) coatings and glycerol have individually been shown to produce low friction in boundary, mixed and full film lubrication. A few studies have been conducted using both glycerol and DLC-coated surfaces to achieve even lower friction in pure sliding boundary-lubricated contacts. However, the literature is lacking studies of how the combination of glycerol and DLC performs in non-conformal rolling/sliding contacts where many common machine components operate. Such a study is presented in this article where a ball-on-disc test rig is used to investigate the performance of the combination of DLC and glycerol at pressures up to 1.95 GPa at various entrainment speeds and slide-to-roll ratios. The investigation shows that the DLC-glycerol combination provides very low friction values, in some cases, below the superlubricity threshold of 0.01, possibly shown for the first time at such high pressure in a non-conformal rolling/sliding contact. The low friction mechanism in full film lubrication is a combination of the low pressure-viscosity and high temperature-viscosity sensitivity of glycerol in combination with thermal insulation of the DLC coating and is presented as thermally assisted liquid superlubricity.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Traction, EHL, Coatings, friction reducing, Superlubricity, Friction, Thermal effects in EHL, DLC, Glycerol
National Category
Tribology (Interacting Surfaces including Friction, Lubrication and Wear)
Research subject
Machine Elements
Identifiers
urn:nbn:se:ltu:diva-72541 (URN)10.1007/s11249-019-1135-1 (DOI)000455190400002 ()2-s2.0-85059784212 (Scopus ID)
Note

Validerad;2019;Nivå 2;2019-01-25 (inah)

Available from: 2019-01-14 Created: 2019-01-14 Last updated: 2019-01-25Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6085-7880

Search in DiVA

Show all publications