Bio-based ionic liquid crystal for stainless steel-sapphire high temperature ultralow friction

In the present work, the biobased protic ionic liquid crystal bis(2-hydroxyethyl) ammonium palmitate (DPA) has been studied as neat lubricant under linear reciprocating sliding at 75 °C, in the liquid crystalline region, and at 110 °C, above its melting point. Three different tribopairs have been studied using AISI 52100 steel, AISI 316L stainless steel and sapphire balls against AISI 316L disks. Tribological results at 75 °C are in agreement with the different sliding pairs and contact conditions. At 110 °C, a sharp friction coefficient reduction to reach an ultralow steady state value of 0.007–0.009, is observed for the sapphire-AISI 316L contact. Wear rate is also reduced in one order of magnitude. Results are related to water content in DPA, as determined by TG-MS. Wear mechanism are discussed upon the basis of optical and scanning electron microscopy (SEM/EDX) and of surface analysis by XPS.This research was funded by Spanish Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación (AEI), and the European Union FEDER Program (Grant # MAT2017–85130-P). “Este trabajo es resultado de la actividad desarrollada en el marco del Programa de Ayudas a Grupos de Excelencia de la Región de Murcia, de la Fundación Seneca, Agencia de Ciencia y Tecnología de la Región de Murcia (Grant #19877/GERM/15)”

Influence of temperature on PA 6−steel contacts in the presence of an ionic liquid lubricant. Poster

Room−temperature ionic liquids (ILs) are salts with a melting point lower than room temperature and are called green solvents because they have properties such as: ♦ Non−flammability, ♦ Negligible volatility, and ♦ High thermal stability. The high thermal stability range (from −74 ºC to 370 ºC in our case) of ILs makes them suitable candidates as high temperature and extreme temperature lubricants. In this work we present the mechanical and tribological properties of polyamide 6−IL dispersion (PA 6+3wt.% IL) under variable load and temperature conditions, against AISI 52100 steel or AISI 316L stainless steel.We wish to thank MEC (Spain) and the EU FEDER program (MAT2002−03947 and MAT2005−00067) and the Fundación Séneca (Región de Murcia, Spain) (PI/00447/FS/04) for financial support. A.E. Jiménez is grateful for a research grant

Antiwear performance of ionic liquid+graphene dispersions with anomalous viscosity-temperature behavior

New dispersions of few-layers graphene (G) in 1-ethyl-3-methylimidazolium ([EMIM]) ionic liquids (ILs) with dicyanamide ([DCA]) or bis(trifluoromethylsulfonyl)imide ([TFSI]) anions have been obtained by mechanical mixing and sonication. IL+0.5 wt% G dispersions show constant viscosity values from 357K (for IL = [EMIM][DCA]) or from 385K (for IL = [EMIM][TFSI]) to 393K. IL + G dispersions with G > 0.5 wt% show linear viscosity increases with increasing temperature, from 306K (for [EMIM][DCA]+1 wt%G) and from 330K to 393K (for [EMIM][TFSI]+0.75 wt%G and [EMIM][TFSI]+1 wt%G). Addition of graphene improves the poor wear reducing performance of [EMIM][DCA], and prevents surface damage on steel when added to [EMIM][TFSI]. Graphene increases the load-carrying ability of ILs, forms a surface layer on the sliding path and retains wear debris, preventing the formation of large abrasive particles.Ministerio de Economía, Industria y Competitividad (MINECO, Spain), EU FEDER Program (Grant # MAT2017-85130-P) Este trabajo es resultado de la actividad desarrollada en el marco del Programa de Ayudas a Grupos de Excelencia de la Región de Murcia, de la Fundación Séneca, Agencia de Ciencia y Tecnología de la Región de Murcia (Grant # 19877/GERM/15) M.D. Avilés ha recibido una beca del MINECO (BES-2015-074836)

Ionanocarbon lubricants. The combination of ionic liquids and carbon nanophases in tribology

The present overview will focus on the tribological applications of what we have called ionanocarbon lubricants, that is, the combination of carbon nanophases (graphene, carbon nanotubes, nanodiamonds, carbon nanodots) and room-temperature ionic liquids in new dispersions, blends, or modified nanostructures and their use in tribology, lubrication, and surface engineering as friction-reducing, antiwear, and surface-protecting agents in thin films and composite materials. Further research lines and factors that limit the practical applications of the outstanding research results are also highlighted. The very recent results in these lines of research make this a necessary brief review.The authors wish to thank the financial support of the Ministerio de Economía y Competitividad (MINECO, Spain) (MAT2014-55384-P). “Este trabajo es resultado de la actividad desarrollada en el marco del Programa de Ayudas a Grupos de Excelencia de la Región de Murcia, de la Fundación Séneca, Agencia de Ciencia y Tecnología de la Región de Murcia (19877/GERM/15)”. María-Dolores Avilés is grateful to MINECO for aresearch grant (BES-2015-074836)

Protic ammonium bio-based ionic liquid crystal lubricants

Bis(2-hydroxyethyl) ammonium stearate (DES) protic ionic liquid crystal (PILC) has been added in 1 wt% and 2 wt% proportion to di-bis(2-hydroxyethyl) ammonium succinate (DSU) protic ionic liquid (PIL) to obtain (DSU+1%DES) and (DSU+2%DES) lubricant blends. The new blends are non-Newtonian fluids with liquid crystalline domains. Addition of (DES) PILC to (DSU) PIL reduces running-in friction coefficient in more than 70% and prevents surface damage, decreasing wear rate in more than one order of magnitude. Optical profilometry, optical and scanning electron microscopy (SEM), energy dispersive (EDX) and X-ray photoelectron spectroscopy (XPS) have been used to analyze surfaces after the tribological tests.This research was funded by Spanish Ministerio de Ciencia e Innovación, Agencia Estatal de Investigación (AEI) , and the European Union FEDER Program (Grant # MAT2017–85130-P ). “Este trabajo es resultado de la actividad desarrollada en el marco del Programa de Ayudas a Grupos de Excelencia de la Región de Murcia, de la Fundación Seneca, Agencia de Ciencia y Tecnología de la Región de Murcia (Grant # 19877/GERM/15 )”

Nuevo nanocomposite de líquido iónico prótico en matriz epoxi

[ESP] En el presente estudio, se ha preparado un nuevo nanocomposite de matriz epoxi modificada mediante la adición de un líquido iónico prótico. Se han determinado sus propiedades térmicas, dinámicomecánicas y su dureza. También, se ha evaluado su comportamiento frente a fricción y desgaste mediante ensayos tribológicos en configuración de punzón sobre disco, obteniéndose mejoras sustanciales con respecto a la resina epoxi sin modificar. Además, se ha realizado un estudio superficial para determinar la distribución del líquido iónico en el interior de la matriz epoxi. [ENG] In the present study, we have prepared a new nanocomposite of epoxy resin modified by addition of a protic ionic liquid. Its thermal and dynamic-mechanical properties have been determined, and also its hardness. Friction and wear resistance have been evaluated by pin-on-disc tribological test, and if we compare its tribological performance with that of neat epoxy resin, better results have been found. Moreover, we have done a superficial study to determinate the ionic liquid distribution in the epoxy matrix.Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT), Escuela Técnica Superior de Ingeniería Agronómica (ETSIA), Escuela Técnica Superior de Ingeniería Industrial (ETSII), Escuela Técnica Superior de Arquitectura y Edificación (ETSAE), Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos y de Ingeniería de Minas (ETSICCPIM), Facultad de Ciencias de la Empresa (FCCE), Parque Tecnológico de Fuente Álamo (PTFA), Vicerrectorado de Estudiantes y Extensión de la UPCT, Vicerrectorado de Investigación e Innovación de la UPCT, y Vicerrectorado de Internacionalización y Cooperación al Desarrollo de la UPCT

Physicochemical characterisation of graphene-ammonium lactate ionic liquid nanofluid.

A new series of nanofluids based on graphene dispersed in 2-hydroxyethylammonium lactate (ML) ionic liquid was developed. Concentrations of 0.1, 0.5 and 1 wt% of graphene were studied and these dispersions were stable after 2 months. Raman spectra showed a strong interaction between ML and graphene. The effect of the concentration of graphene and temperature on the viscoelastic behaviour and conductivity of the nanofluids was studied. An unexpected decrease in the viscosity was found with a low concentration of graphene due to the suppression of hydrogen bonding of the ionic liquid. Shear thinning effects appeared with higher concentrations of graphene and Ostwald and Herschel-Bulkley equations were used to describe the steady-state viscosity results. Creep-recovery tests were also performed, and the data were fitted to a complex Burgers model for the nanofluid with 1 wt% of graphene, with a 47 % of elastic response. The complexity of the model was related to the presence of different molecular arrangements in the nanofluid. An enhancement of the conductivity was observed with increasing values of the graphene concentration. The effect of temperature on viscosity and electrical conductivity was successfully modelled by using both Vogel-Fulcher-Tammann and Power Law equations. Electrochemical characterisation at room temperature was also carried out, finding an irreversible oxidation at 1 V only for the highest concentration (1 wt%). The concentration of percolation was estimated in the range of 0.5 to 1 wt% of graphene.The authors acknowledge the financial support of Ministerio de Economía y Competitividad and Agencia Estatal de Investigación (MINECO and AEI, Spain), EU-FEDER (MAT2017-85130-P, and PID2021-122169NB) and the Fundación Seneca, Agencia de Ciencia y Tecnología de la Región de Murcia (‘Ayuda a las Unidades y Grupos de Excelencia Científica de la Región de Murcia’; Grant # 19877/GERM/15). P.M. M.-R. is grateful to Fundación Séneca for FPI research grant (21574/FPI/21)

Procedimiento de fabricación, preparación y composición de nuevas dispersiones polímero cristal líquido con propiedades mejoradas

Número de publicación: 2 268 935 Número de solicitud: 200402202Procedimiento de fabricación, preparación y composición de nuevas dispersiones polímero cristal líquido con propiedades mejoradas. Esta invención presenta la composición y fabricación de distintas mezclas poliméricas termoplásticas con cristales líquidos termotrópicos dispersados en la superficie, y cuya finalidad es por una parte, la mejora sustancial de la resistencia a la fricción y al desgaste por deslizamiento contra aleaciones metálicas y por otra, la mejora de los procesos de moldeo de estas piezas.Universidad Politécnica de Cartagen

Rheological study of new dispersions of Carbon Nanotubes in the ionic liquid 1-ethyl-3-methylimidazolium dicyanamide

Dispersions of three different types of carbon nanotubes in a 1 wt.% proportion in the low viscosity 1-ethyl-3-methylimidazolium ([EMIM][DCA]) ionic liquid have been obtained. The neat ionic liquid presents Newtonian behavior, but the addition of carbon nanotubes increases the viscosity with respect to [EMIM][DCA] in the following order: Single-Walled Carbon Nanotubes (SWCNTs) > aligned Multi-Walled Carbon Nanotubes (aligned-MWCNTs) > Multi-Walled Carbon Nanotubes (MWCNTs), and the resulting fluids show non-Newtonian behavior. SWCNTs and MWCNTs dispersions present shear thinning with increasing shear rate, but a shear thickening effect for aligned-MWCNTs at intermediate shear rate values at room temperature has been observed. This effect disappears at 100 ºC. The thermal response of the viscosity of [EMIM][DCA] and the CNTs-IL dispersions can be fitted to the Arrhenius model. For[EMIM][DCA] and the dispersion with MWCNTs the viscous behavior prevails at low frequencies, with a cross point at a critical frequency value which decreases with increasing temperature. However, the dispersions of SWCNTs and aligned-MWCNTspresent storage modulus values higher than loss modulus in the whole range of frequency.The authors acknowledge the Ministerio de Economía, Industria y Competitividad (MINECO, Spain), the EU FEDER Program (Grants # MAT2014-55384-P and # MAT2017-85130-P), and Fundación Séneca - Agencia de Ciencia y Tecnología de la Región de Murcia “Ayuda a las Unidades y Grupos de Excelencia Científica de la Región de Murcia (Programa Séneca 2014)” (Grant # 19877/GERM/14), for financial support. M.D. Avilés acknowledges a research fellowship (Grant # BES-2015-074836) to MINECO

New Water-Ethylene Glycol Lubricants with Stearate Ionic Liquid Crystal Additive

The main purpose of the present study is to improve the tribological performance of aqueous lubricants with the use of ecofriendly, fatty acid-derived additives. The protic ionic liquid crystal bis(2-hydroxyethyl)ammonium stearate (DES) has been added to 50:50 water+ethylene glycol (W–EG) to obtain (W–EG)+0.5%DES; (W–EG)+1%DES and (W–EG)+2%DES emulsions. The new lubricants have been studied in sapphire-AISI (American Iron and Steel Institute) 316L stainless-steel pin-on-disk sliding contacts. The addition of DES reduces the friction coefficient by up to 76% and wear rate by up to 80%, with respect to (W–EG). The best performance is found for the emulsions with the lower proportion of DES (0.5 and 1 wt.%). These results have been related to viscosity and turbidity values. Wear mechanisms have been studied by Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (SEM/EDX) and by Raman microscopy. While W–EG shows a severe abrasive mechanism, no abrasion marks are present inside the wear track after lubrication with (W–EG)+0.5%DES, the emulsion with the lowest wear rate. After lubrication with W–EG, an increase in oxygen content is observed inside the wear track, as determined by EDX and confirmed by Raman microscopy, which shows the presence of iron oxides. The addition of DES reduces these oxidation processes.publishedVersio