Nano-Fe3O4 modified carbon fiber reinforced polymer composites with friction self-healing and excellent wear resistant functionalities

The interfacial bonding strength between carbon fibers and the resin matrix of carbon fiber-reinforced resin-based composites (CFRC), as well as the formation of friction films, play a decisive role in determining the tribological properties of CFRC. Effective design to construct the interfacial microstructures is crucial yet remains highly challenging for higher friction coefficient (μ_d) while improving the wear resistant of composites. Herein, this study employed hydrothermal and solvothermal methods to in-situ synthesize magnetic nano-Fe₃O₄ with diverse morphologies and sizes on the surface of carbon fibers, significantly improving the wear resistance of composites and endowing the composites with friction self-healing function. The results demonstrated that the successful growth of nano-Fe₃O₄ significantly increased the surface roughness and wettability of the carbon fibers, thereby contributing to the enhancement of the interfacial bonding strength of the composites. Owing to the nano-pinning effect exerted by nano-Fe₃O₄ on the resin matrix after its in-situ growth on the surface of CFs, the tensile strength and bending strength are increased by 39.4 % and 27.7 % respectively. Experimental data revealed that the μ_d of Fe₃O₄-Ⅲ modified composite was 0.2048, representing a 24.0 % increase compared to the unmodified material. In addition, owing to the strong magnetism of nano-Fe₃O₄, the magnetic wear debris generated during the friction process can be adsorbed onto the friction surface or filled into surface pores. This facilitates the continuous formation of a friction film during the continuous friction processes, thereby enabling the self-healing function and significantly enhancing the wear resistance of the composites. Based on the formation of the hard friction film, the wear rate of the modified composite was reduced by 65.4 %. This study offers novel insights into the surface modification of carbon fibers and the design of interfacial structures for functional polymer-based composites, which is conducive to obtaining superior wear resistance and provides great potential for applications in transmission and braking systems.