A. Fernández-González

Lubrication of DLC Coatings with Two Tris(pentafluoroethyl)trifluorophosphate Anion-Based Ionic Liquids

The lubrication of a Cr-DLC coating with ethyl-dimethyl-2-methoxyethylammonium tris(pentafluoroethyl)trifluoropho-sphate [(NEMM)MOE][FAP] and 1-butyl-1-methylpyrro-lidinium tris(pentafluoroethyl)trifluorophosphate [BMP] [FAP] ionic liquids (ILs) as 1 wt% additives to a polyalphaolefin (PAO 6) was studied. Zinc dialkyldithiophosphate (ZDDP) was also used as reference in order to evaluate the effectiveness of the ILs. Reciprocating ball-on-plate tribological tests at loads of 20 and 40 N were performed. The results showed that both ILs exhibited a friction reduction, especially at the lowest load tested. Antiwear properties were also improved; the PAO 6 + 1% [BMP][FAP] mixture was slightly better, close to the values for PAO 6 + 1% ZDDP. Scanning electron microscopy (SEM) images and X-ray photoelectron spectroscopy (XPS) analysis indicated that the additive–surface interaction was responsible for the tribological improvement.

FAP − Anion Ionic Liquids Used in the Lubrication of a Steel–Steel Contact

AbstractnThis study compares the tribological behavior of two ionic liquids ([BMP][FAP] and [(NEMM)MOE][FAP]) used as oil additive for the lubrication of a steel–steel contact. Friction and wear experiments were performed using a HFRR test machine. Friction coefficient and electrical contact resistance were measured during the tests, and the wear surface was analyzed by confocal microscopy and XPS. The tribological results showed that both ionic liquids used as additive decrease friction and wear but the [BMP][FAP] had a better performance than the [(NEMM)MOE][FAP] due to its higher reactivity with the steel.

Antifriction and Antiwear Properties of an Ionic Liquid with Fluorine-Containing Anion Used as Lubricant Additive

Tribological behavior of trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl) imide [P66614][NTf2] ionic liquid (IL) used as additive in a diester oil at concentrations of 0.25, 0.5 and 1 wt% was studied in this research. The IL solubility in the base oil was measured using the inductively coupled plasma mass spectrometry (ICP-MS) technique, and corrosion analysis was done at room temperature at relative humidity of 49–77%. Tribological tests were conducted for 30xa0min at room temperature, 15xa0Hz frequency, 4xa0mm of stroke length, a load of 80xa0N (corresponding to 2 GPa of maximum contact pressure) and relative humidity of 35–53%. Friction coefficient was recorded during tests, and the wear scar was measured by confocal microscopy. Worn surface was also analyzed by SEM, EDS and XPS. Results showed that a saturated solution of [P66614][NTf2] in the base oil contains about 30 wt% of IL and corrosion activity for the highest concentration of IL (1 wt%) was not found after a 20-day test. Although the base oil and the mixtures had similar friction behavior, only the 1 wt% sample exhibited slightly lower wear volume than the base oil. SEM images exhibited similar wear track width (707–796xa0µm) and wear mechanism (adhesive) for all samples tested. In addition, the EDS spectra only showed the elements present in the steel. Finally, the XPS measurements could not detect differences regarding iron chemical state among the samples, which is consistent with the tribological behavior obtained.

Lubrication of DLC and TiN Coatings With Two Ionic Liquids Used as Neat Lubricant and Oil Additive

Thin hard physical vapour deposited (PVD) coatings are today frequently used in order to improve the tribological performance of forming tools, cutting tools, and machine elements [1]. PVD TiN coating is widely used in high-speed steel cutting tools. Studies on the friction, wear characteristics and failure mechanisms of this coating have shown that it can reduce wear and diminish the failure of components. This coating frequently offers good corrosion protection and surface finish, high wear resistance and low coefficient of friction. On the other hand, PVD DLC (diamond-like carbon) coating provides a low friction and a high sliding wear resistance to enhance the tribological behavior and the durability of running components. DLC is becoming widely used as surface coating for machine components in lubricated systems, especially in the automotive industry. DLC coatings are nowadays frequently used in applications under high stress and/or under boundary or mixed lubrication regime and the range of use for these coatings keep growing rapidly.Copyright

Lubrication Properties of the Ionic Liquid Dodecyl-3 Methylimidazolium bis(trifluoromethylsulfonyl)imide

The ionic liquid (IL) dodecyl-3 methylimidazolium bis(trifluoromethylsulfonyl)imide was tested as neat lubricant and as additive (at 1 and 4xa0wt%) in a polar oil (diester). Tribological tests were performed using a reciprocating configuration for 90xa0min at 30 and 70xa0N, 10xa0Hz, 4xa0mm stroke length, and at room temperature and 100xa0°C. Wear volume and surface–IL interaction were determined by confocal microscopy, SEM, and XPS. The main findings were: Neat ionic liquid showed the best tribological behavior; the IL-containing mixtures had similar behavior than the base oil at the lower load; meanwhile, the mixture with 4xa0wt% of IL outperformed the antiwear behavior of the neat base oil at the higher load; surface–IL chemical interaction was found mainly at 100xa0°C.