Effect of magnetic field on the tribological performance of waterborne polyurethane coatings with magnetized graphene oxide

In this study, graphene oxide (GO) and Fe 3 O 4 were bonded to prepare magnetized graphene oxide (MGO). The MGO was characterized by transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Research results showed that Fe 3 O 4 nanoparticles were uniformly loaded onto the GO surface by chemical grafting, making MGO ferromagnetic. MGO/WPU nanocomposite coatings were prepared by adding different contents of MGO to WPU, and the tribological properties of coatings were tested in different magnetic field intensities (0 mT, 20 mT and 40 mT). Tests showed that the anti-friction and wear-resistance of the nanocomposite coatings were significantly improved by magnetic field. The 0.5 wt% MGO/WPU nanocomposite coating had the best tribological performance in a 40 mT magnetic field, with a friction coefficient of 0.094 and a wear rate of 0.24 × 10 −4 mm 3 /(N·m). The formation of the stable transfer film is a dynamic equilibrium process, and the magnetic field promotes the formation of the transfer film and strengthens the adhesion of the transfer film. Additionally, a magnetic field-nanocomposite coating energy system model was proposed. • MGO/WPU composite coatings were prepared by adding MGO to WPU with different mass fractions, and the tribological properties were tested in magnetic fields with different magnetic field intensities (0 mT, 20 mT and 40 mT). • The results showed that the tribological performance of the composite coatings was significantly improved in magnetic field. • At the same time, the formation of the stable transfer film is a dynamic equilibrium process, and the thermal effect of the magnetic field prevents the generation of microcracks. • Additionally, a magnetic field-composite coating energy system model was proposed.