Construction of Highly Ordered Fluorinated Graphene Composite Coatings with Various Fluorine Contents for Enhanced Lubrication Performance

The presence of fluorine makes fluorinated graphene (FG) exhibit extraordinary properties and provides effective route to engineer and modulate the surface and interface properties, which endows FG with promising prospect as ultrathin solid lubricant. Herein for the first time, a strongly integrated FG composite coating was fabricated by facile and scalable solution-based process. The pretreatment with alkali hydroxides both enhances the dispersibility of FG in aqueous medium and realizes the control of fluorine content. The incorporated dopamine could simultaneously function as adhesion and mechanical buffer layer. The as-prepared coatings almost show the full coverage (>90 %) of FG nanosheets over centimeter scale substrates with uniform thickness of 2.36-2.66 nm. The synthesis-structure-performance relationship, particularly the influence of fluorine content and coating structure on the lubricating properties, has been systematically investigated and discussed. Based on this fascinating testing platform, the results of tribological investigations demonstrate the composite coating with higher fluorine content has more stable friction state, lower friction coefficient, and longer duration.