Tribological Aspects of Control over Frictional Interaction between Solids in the Presence of Liquid Crystals

Abstract

The development of novel additives ensuring improved performance of lubricating materials is one of the pressing problems of modern tribological engineering. In this respect, liquid crystals (LC) have captured keen attention of tribologists due to their unique lubricity. The experience accumulated in this sphere has proved that LC behave most efficiently as antifrictional additives when found in the mesomorphic state. The work presents investigation results of the mesomorphic state and lubricating action of cholestric LC distinguished by their chemical structure and physical properties, and their mixtures with Vaseline oil. The phase state and the phase transition temperature of LC structures were estimated by the polarizing microscopy with application of a purposefully manufactured device. The device is intended to visualize and perform a continuous control of phase variations in LC mixtures in response to temperature. The tribological tests were carried out within the temperature interval 0.1 divided by 0.5 m/s and 0.1 divided by 3.0 MPa loads for the steel-on-steel friction pair using a face friction machine following the disc-on-cylinder end geometry under a given test temperature.