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

Abstract

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 hightemperature tribology.

Functional Carbon from Nature: Biomass‐Derived Carbon Materials and the Recent Progress of Their Applications

“…Reproduced with permission. [429] Copyright 2022, ACS. benzene rings or C = C bonds, indicating that a high level of graphitization is beneficial to adsorption performance.…”

“…[428] To solve these problems, Chen et al fabricated graphitized C/Fe3O4 magnetic nanocomposites (g-C/Fe 3 O 4 ) with interpenetrating network structures using cassava starch as the carbon source via hydrothermal and ball milling. [429] This nanocomposite is used as a lubricant additive in rapeseed oil and shows superb tribological properties with a high extreme pressure of 804 N and a low friction coefficient of 0.029 at 155 °C. In addition, the wear scar depth of g-C/Fe 3 O 4 is the smallest among all the samples, which is 10.44 μm according to the 3D profile of the wear scar in Figure 21l.…”

“…l) Optical photographs of worn surfaces and the 3D profile of the wear track of the steel ball after friction tests (at 392 N, 155 °C, 0.3 wt%) of g-C/Fe 3 O 4 . Reproduced with permission [429]. Copyright 2022, ACS.…”