Tribological Performance Studies of Waterborne Polyurethane Coatings with Aligned Modified Graphene Oxide@Fe3O4

In this study, the chemical graft method was used to connect modified graphene oxide (GO) and Fe3O4 through covalent bonds. To make full use of the tribological properties of graphene, aligned graphene oxide@Fe3O4/waterborne polyurethane (GO@Fe3O4/WPU) was prepared in a magnetic field and tribological experiments were carried out on it. The GO@Fe3O4 was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and a transmission electron microscopy (TEM). The characterization results show that Fe3O4 is successfully loaded on the surface of GO and GO@Fe3O4 has better dispersibility in WPU. Among the coatings without alignment inducement of GO@Fe3O4, 0.5 wt % GO@ Fe3O4/WPU has the lowest friction coefficient and wear rate. In addition, the 0.5 wt % aligned GO@Fe3O4/WPU composite coating has the lowest friction coefficient and wear rate compared with nonaligned and pure WPU coatings. The excellent tribological properties of the aligned composite coating come from its ability to quickly form a uniform and continuous transfer film on the friction counterpair, which avoids direct friction between the friction counterpair and the coating.