Tribological properties of magnetite nanoparticles with various morphologies as lubricating additives

The aim of this paper was to investigate the tribological properties of magnetite (Fe3O4) nanoparticles (NPs) with various morphologies (i.e., hexagonal, octahedral, and irregular morphologies) utilized as lubricating additives on a four-ball tribo-tester. The diameters of wear scar and the friction coefficients were measured using a scanning electron microscope (SEM) and a statistical software, respectively. The properties of the friction pair surfaces were examined by a SEM, atomic force microscope, energy dispersive X-ray spectroscope, and X-ray photoelectron spectroscope. The results show that the Fe3O4 NPs, especially the NPs with hexagonal morphology, have superior antifriction properties as lubricating additives. In addition, the antifriction mechanism of the Fe3O4 NPs as lubricating additives was also discussed.