Three new ionic liquids with different anions and the same cation were synthesized from fatty acids through a metathesis reaction. All the ionic liquids were identified via NMR and FTIR and several properties (density, viscosity, thermal, and environmental) were measured. Traction tests were performed under different entrainment speeds (10-2000 mm/s), at slide-roll ratio (SRR) of 50% and 30 N-load, and at different temperatures (40, 60, 80 and 100 ºC) using a mini-traction machine (MTM). Tribofilm formation tests were also made in the MTM at 50 N-load, 150 mm/s of entrainment speed, at SRR of 50% and temperature of 100 ºC, for 60 minutes. This work showed that the alkyl chain length in the anion affects properties such as viscosity, toxicity, biodegradability and lubrication. Viscosity decreased with increasing alkyl chain length but only below 60ºC, at higher temperatures the viscosity values of the ionic liquids converge. The toxicity and biodegradability increased with the alkyl chain length, but these novel ionic liquids are much better from both toxicity and biodegradability points of view than the [N8881][TFSI] ionic liquid, which contains the same cation and anion not coming from fatty acids. The ionic liquids at low temperature (40 ºC) performed under elastohydrodynamic lubrication and changed to mixed lubrication at higher temperatures and decreasing speeds, according to the alkyl chain length of each anion. All ionic liquids adsorbed on the steel surfaces, and the tribofilm thickness and the kinetics of formation were different.

This work deals with the determination of several wetting properties (contact angle, surface tension, polarity fraction and spreading parameter) of six novel fatty acid anion-based ionic liquids (FAILs): methyltrioctylammonium hexanoate [N 8881 ][C 6:0 ], methyltrioctylammonium octanoate [N 8881 ][C 8:0 ], methyltrioctylammonium laurate [N 8881 ][C 12:0 ], methyltrioctylammonium palmitate [N 8881 ][C 16:0 ], methyltrioctylammonium stearate [N 8881 ][C 18:0 ] and methyltrioctylammonium oleate [N 8881 ][C 18:1 ]. Surface tension was determined at temperatures from 293 to 333 K, exhibiting a linear decrease within the temperature range. Contact angle measurements were performed on five different surfaces (steel, aluminum, tungsten carbide, cast iron and bronze) using 3 test liquids (water, diiodomethane and ethylenglycol)and each of the synthesized FAILs. Polarity fraction (PF) and the spreading parameter (SP) were calculated in order to gain a deeper understanding of wetting characteristics of these FAILs. Despite the similarity of the obtained results with all FAILs and surfaces, [N 8881 ][C 6:0 ] and [N 8881 ][C 8:0 ] with both cast iron and bronze surfaces were the best surface-FAIL combinations regarding wettability.

This paper studies the tribological behavior of three fatty acid anion-based ionic liquids: methyltrioctylammonium octanoate ([N 8881 ][C 8:0 ]), methyltrioctylammonium laurate ([N 8881 ][C 12:0 ]) and methyltrioctylammonium palmitate ([N 8881 ][C 16:0 ]) used as additive at 0.5, 1 and 2 wt% in an ester base oil.The tribological experiments were performed in two different tribometers: a Bruker UMT-3 using a reciprocating "ball-on-disc" configuration for pure sliding tests and a Mini Traction Machine (MTM) for rolling/sliding tests. After sliding tests, the wear scar was analyzed by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). Sliding tests results showed both friction and wear reduction of the mixtures with respect to the ester only at 25 ºC. The worse tribological behavior at 100 ºC could be attributed to the moderate thermal stability of these ionic liquids. Under rolling/sliding conditions, samples displayed similar antifriction and ECR behavior than the base oil at high speeds, changing to a higher friction and lower ECR at low speeds and increasing temperatures. EDX analysis showed mainly the steel disc elements. The XPS oxygen signal showed higher amount of C=O bond on the worn surface after reciprocating tests at 25 ºC, which could be attributable to IL-surface interaction and can explain the better wear reduction performance.

Tribological behavior of three Fatty Acid anion-based Ionic Liquids (FAILs) with the same ammonium cation ([N8881]) and different anions ([C16:0], [C12:0] and [C8:0]) were studied. Four different tribopairs (steelsteel, aluminum-steel, bronze-steel and tungsten carbide-steel) were tested for each FAIL using a ball-ondisc reciprocating test for 30 min (room temperature, 50 N-load, 4 mm of stroke length, and 15 Hzfrequency). Aluminum and tungsten carbide surfaces did not show evidence of oxidation changes, contact pressure and hardness being, respectively, the main parameters controlling tribological behavior. Bronze and steel samples showed surface oxidation changes during tests, which influenced friction and/or wear results. An increase in alkyl chain length of the anion led to an increase in tin oxidation of bronze and the formation of a low friction film of Fe3O4 on steel.

Placing an electric motor (EM) inside the transmission housing of a hybrid electric vehicle (HEV) implies that the automatic transmission fluid (ATF) needs to accomplish additional requirements. Among these requirements, electrical compatibility is of critical significance. This study investigated the influences of the additive concentrations of three commercial ATFs on their electrical compatibilities and tribological performances. Two variations of each ATF with different concentrations of the original additive packages were prepared. The viscosity, electrical conductivity, permittivity, resistivity, dielectric dissipation factor, breakdown voltage, and tribological performance of the nine resulting ATFs were measured. All the ATFs were found to be electrically compatible and showed dissipative performance and sufficiently high breakdown voltage, even at increasing additive concentrations. The tribological performances of the ATFs formulated with the API (American Petroleum Institute) Group III base oils had improved wear reduction at the highest additive concentrations; the better wear performance was related to the formation of iron phosphates and polyphosphates on the worn surface.