Ionic liquids as a neat lubricant applied to steel–steel contacts

This paper studies the use of 3 ionic liquids ([(NEMM)MOE][FAP], [BMP][FAP] and [BMP][NTf2]) as neat lubricant within steel–steel contact conditions. Tribological tests (at 40 and 100 °C) were conducted in a HFRR tribometer and hence a complementary study was developed using a MTM tribometer. The wear surface on the discs was measured after the HFRR tests by confocal microscopy and also analyzed by SEM and XPS. The [BMP][NTf2] showed the lowest friction coefficient in the MTM and HFRR tests at 40 °C but at 100 °C its tribological behavior worsened due to its lowest viscosity. Similar results were found for wear behavior. Both antifriction and antiwear results were related to the tribofilms formation from the ECR and XPS measurements.