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.