Laser Irradiation-Induced SiC@Graphene Sub-Microspheres: A Bioinspired Core-Shell Structure for Enhanced Tribology Properties

Friction generally happening among all moving material interfaces wastes nearly one-third of total mechanical energy in the world each year, although different kinds of lubricants are adopted. Particle additives, like diamond, inorganic fullerene, and graphene, can enter tribological contacts to reduce friction and protect surfaces from wear. However, the growth of such additives with spherical morphology and high dispersibility in oil without molecular ligands is a major problem. Inspired by the impressive dispersion stability of Noctiluca scientillans in ocean, one novel core-shell composite constructed with superhard SiC sub-microsphere as core and exclusive floating flat-blade graphene sheet as shell (SiC@G) is designed. These core-shell SiC@G sub-micropheres are synthesized for the first time by in situ pulsed laser irradiating commercial SiC powders in liquid at ambient conditions. Both laser-stimulated surface tension energy release and photothermal decomposition involved in the laser irradiation process assure the reshaping of SiC particles and the formation of graphene sheets derived from SiC surface. Due to the synergistic effect of SiC spheres changing effectively sliding friction into rolling friction and flexible self-lubricating graphene forming a tribofilm easily, such composites as additives remain well dispersed in lubricating oil and exhibit enhanced antiwear and friction-reduction performance.