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.