Low-Temperature-Graphitized and Interpenetrating Network C/Fe 3 O 4 Magnetic Nanocomposites with Enhanced Tribological Properties under High Temperature.

Although the core-shell structure magnetic nanocomposites have been widely used as lubricant additives, their tribological properties are still poor under high temperature and high load. Herein, the graphitized C/Fe 3 O 4 magnetic nanocomposites (g-C/Fe 3 O 4 ) 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 Fe 3 O 4 . Moreover, the g-C/Fe 3 O 4 used as a lubricant additive in rapeseed oil exhibited excellent tribological properties and high thermo-stability under 155 °C and 980 N, with the friction coefficient reduced by 32.8% compared to the independent Fe 3 O 4 . The enhanced tribological performance of g-C/Fe 3 O 4 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 Fe 3 O 4 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.