Complex fluids in tribology to reduce friction: Mesogenic fluids, ionic liquids and ionic liquid crystals

The tribological behavior of complex fluids was investigated to study the mechanisms, which cause low friction values. Therefore reciprocating sliding tests using two different geometries (cylinder-on-disc, ring-on-disc) were performed. Afterwards the characteristics of the wear scars were analyzed. In addition, in-lubro infrared analysis executed to assign the relative change of the content of water during a tribological test. The mesogenic fluid MF-02/06 ( μ ≈ 0.005 ), imidazolium-based ionic liquids ( μ ≈ 0.02 ) and ionic liquid crystals ( μ ≈ 0.01 ) showed low friction coefficients after a specific running-in time using cylinder-on-disc geometry. The wear scars showed a characteristic grooved structure for the fluids with the lowest friction coefficients. Using in-lubro IR-spectroscopy, it was detected that the water content decreases during the tribological test, which influences the corrosive behavior.