Tuning fluorine content of fluorinated graphene by an ionothermal synthesis method for achieving excellent tribological behaviors

Abstract

Fluorinated graphene (FG) has been an excellent lubricant additive due to its wider layer spacing and weaker interlayer forces, and FG with different fluorine content can exhibit different tribological performance. Herein, an ionothermal synthesis method was provided to prepare FG nanosheets with different fluorine content. Under the dual function of the ionic liquids ([C16C1im][Br]) and the temperature, the [C16C1im][Br] can work well as both an intercalation agent and polar catalyst, thus achieving tuning fluorine content of FG. Surprisingly, due to the chemical stability of [C16C1im][Br], the [C16C1im][Br] used in the exfoliated process of FG can be recycled and reused at least 5 times and still remain favorable exfoliation effect. Moreover, it can be obtained that friction coefficient and wear track width are reduced by 53.1 % and 52.8 % through adding FG nanosheets into PAO4 oil, the function generated by breaking of C–F bonds can form an adsorbed film on the friction surface, thus offering a synergistic lubricant mechanism with formation of FG tribo-film. Therefore, the FG dispersed into PAO4 oil can greatly enhance the tribological behaviors during the friction process.