TribologicalBehaviors of Ionic Liquid FunctionalizedGraphene/Carbon Nanotube Sandwich Nanomaterials with Frictional Surfacesin PAO

The poor dispersibility and extended running-in period of nanomaterials have inhibited the development of solid–liquid two-phase lubrication systems. Herein, a sandwich nanomaterial (ionic liquid [IL]-graphene oxide [GO]/carbon nanotubes [CNTs]) with a specifically designed molecular structure was developed. The incorporation of nanomaterials into polyalphaolefin (PAO 6) yields long dispersion, ultrashort run-in period, and good friction stability. By FIB-TEM, AFM, and MD, superior tribological properties result from the formation of solid adsorption and friction chemically reactive films, and the interlayer slip of GO. In addition, CNTs significantly improve the load-bearing capacity by conducting and apportioning the compressive stress on the material surface; IL electrostatic interactions induce nanoparticles to preferentially adsorb at the friction interface to form a solid adsorption film.