Investigating the fluorination degree of FG nanosheets on the tribological properties of FG/PI composite coatings

Abstract

In this work, fluorinated graphene (FG) nanosheets with different F/C fluorination degree were synthesized by a convenient gas phase fluorination method. Ionic liquids was used to modify the FG to improve its dispersion and compatibility in polyimide (PI). The thermal, mechanical and tribological properties of FG/PI composite coatings were investigated systematically. The morphology of FG was observed by Transmission electron microscopy (TEM) and scanning probe microscope (SPM). The physical and chemical properties of the FG were characterized by a large number of measurement methods, such as X-ray powder diffraction (XRD), Raman spectra, X-ray photo-electronic spectroscopy (XPS) and so on. Fourier transformed infrared spectra (FTIR) was used to confirm the successful modification of ILs. And the Chemical composition of the PI coating was investigated by XPS and FTIR measurements. On the basis of the stable dispersion of FG in the PI matrix, compared with pure PI, the composite coating with (reduced graphene oxide) rGO owned slightly improved thermal, mechanical and tribological properties and the composite coating with FG displayed significant improvement, especially when the F-doped degree was the highest.