Low-Temperature-Graphitized and Interpenetrating Network C/Fe3O4 Magnetic Nanocomposites with Enhanced Tribological Properties under High Temperature

Although the core-shell structure magnetic nano-composites have been widely used as lubricant additives, their tribological properties are still poor under high temperature and high load. Herein, the graphitized C/Fe3O4 magnetic nano-composites (g-C/Fe3O4) with an interpenetrating network structure were successfully fabricated by an in situ hydrothermal carbonization method combined with a subsequent ball milling process at room temperature. The results showed that the ball milling process not only promoted the transformation of graphitized carbon but also effectively eliminated the interfacial effect between carbon and Fe3O4. Moreover, the g-C/Fe3O4 used as a lubricant additive in rapeseed oil exhibited excellent tribological properties and high thermo-stability under 155 degrees C and 980 N, with the friction coefficient reduced by 32.8% compared to the independent Fe3O4. The enhanced tribological performance of g-C/Fe3O4 could be attributed to the graphitized carbon and its interpenetrating network structure under low load force (392 N), while under high load force (980 N), it could be ascribed to the synergistic effect between the graphitized carbon and magnetic Fe3O4 nanoparticles. This work not only offers a method for the synthesis of nanocomposite lubricant additives but also shows great potential in practical applications for high-temperature tribology.