Analysis of the ultralow friction behavior of a mesogenic fluid in a reciprocating contact

Frictional contacts that are lubricated by a mesogenic fluid exhibit ultralow friction coefficients. It is assumed that these specific mesogenic fluid forms a liquid crystalline-like structure in the sliding contact that induces hydrodynamic lubrication. This effect has been reproducibly observed in a reciprocating friction system after a certain running-in period.The aim of the present work was to study the tribological behavior of a specific mesogenic fluid in detail in contrast to standard lubricants. Tribological experiments were performed using a reciprocating cylinder-on-disc test machine. The obtained results show that ultralow friction coefficients can reproducibly be realized. Special attention was given to the chemical transformation of the mesogenic fluid during the tribological test. It is assumed that chemical and physical interactions of the mesogenic fluid with the surface of the test specimens induce a change in the rheological parameters of the mesogenic fluid and therefore, the tribological behavior is strongly affected.A better understanding of the tribological behavior is essential for the development of efficient production routes and for the qualification of mesogenic lubricants for possible future applications.

► In this study we analyse the tribological behavior of a mesogenic fluid.
► After a certain running-in time the fluid exhibits ultralow friction.
► We find that the fluid forms chelat-complexes with nascent iron ions.
► We find that this chemical reaction changes the rheological and tribological behavior.
► An induced liquid-crystalline like orientation and chemical change leads to ultralow friction.