Layer-by-Layer Assembled Graphene Oxide on Carbon Fiber toward Phosphate Bonded Coatings with Excellent Interfacial Bond and Tribological Performance.

To enhance the interfacial property, carbon fiber (CF) was modified with graphene oxide (GO) using a layer-by-layer self-assembly method and subsequently incorporated into phosphate bonded coatings as a reinforcement. CF modified with GO (CF-GO) was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometer, Raman spectroscopy, and thermogravimetric analysis. Additionally, the tribological behavior of phosphate bonded coatings with CF-GO was investigated. The results show that GO is grafted onto the CF surface through electrostatic interactions. Besides, the CF surface becomes rougher due to the modification of GO, leading to a stronger interfacial bond between CF and the coating. Notably, as the content of CF-GO increases, both the friction coefficient and the wear rate of the coating decrease. CF-GO can form a lubricant film on the worn surface, which leads to a decrease in the friction coefficient and wear rate. Moreover, in CF-GO, CF assumes the role of a tree trunk, while GO functions as branches, collaboratively bridging cracks, as well as altering and impeding crack propagation pathways, which can consume the fracture energy and improve the cohesive strength of the coating, further contributing to a lower wear rate. Specifically, the coating with 15 wt % CF-GO exhibits a 34% reduction in the friction coefficient and a 58% decrease in the wear rate compared to those of the coating without CF-GO. These findings highlight the significant potential of CF-GO in enhancing the tribological properties of phosphate bonded coatings, making them more durable for antiwear applications.