Multiscale Study on the Solid-Liquid Synergistic Lubrication Mechanism of Graphite and Liquid Lubricant in Polymer Composites

Abstract

To investigate the solid-liquid synergistic lubrication mechanism of graphite and liquid lubricant, graphite and poly α-olefin base oil (PAO) were used as self-lubricating additives to evaluate their synergistic effect in polymer composites. At macroscopic view, the composites possess excellent properties with a nanoindentation modulus of 3.8 GPa, coefficient of friction (COF) of 0.0998, as well as wear rate of 1.3×10-14m3/N·m. Both transfer film and lubricating oil film exist on the friction interface, and lubricating oil film protects the counter ball from excessive oxidation. At the microscopic, PAO destroy the interlayer structure of graphite, making it easier to form a transfer film on counter ball. The weak chemical bond between graphite and PAO benefits the formation of lubricating oil film.

Keywords: solid-liquid synergistic lubrication, polymer composites, first-principles, molecular dynamics (MD) simulation