Graphene/h-BN Nanosheet/Nanosphere Composites Constructed by In Situ Laser Irradiation with Synergistically Improved Tribological Performance

Abstract

Graphene/hexagonal boron nitride nanocomposites with different dimensions have great application prospects in the field of lubrication due to their unique layered structure and excellent mechanical properties. However, due to their complex synthesis process, easy agglomeration, and poor stability, graphene/hexagonal boron nitride nanocomposites have not yet been applied in lubricating applications. Herein, a simple and green in situ laser irradiation method is proposed to construct two-dimensional (2D) reduced graphene oxide (rGO) nanosheets and zero-dimensional (0D) hexagonal boron nitride nanosphere 2D/0D nanocomposite (L-rGO/h-BN). During the one-step laser irradiation in liquid, the GO nanosheets were reduced to rGO nanosheets. Meanwhile, the hexagonal boron nitride (h-BN) transformed from nanoflakes to nanospheres via a pulsed laser heating and reshaping process and embedded into the multilayer graphene nanosheets. The spherical h-BN nanoparticles as interlayer support can maintain the 2D graphene with a more stable layered structure, while the insertion of graphene sheets also effectively inhibits the agglomeration of the spherical h-BN nanoparticles. Therefore, a hierarchical 2D/0D layered rGO/h-BN nanocomposite was formed. Importantly, such composite nanoparticles can well disperse in the lubricating oil without significant precipitation for over 30 days and show remarkably improved tribological performance. This is due to the synergistic lubricant effect of the deposition repair effect from rGO nanosheets reducing wear and micro-bearing effect from h-BN nanospheres reducing friction by changing sliding friction into rolling friction.