Improving the Tribological Performance of Phosphate-Bonded Coatings Reinforced by Carbon Fiber/Graphene Oxide

To enhance the interfacial bond strength of carbon fiber (CF), graphene oxide (GO) was grafted onto the CF surface byγ-aminopropyl triethoxysilane, and CF modified with GO (CF-GO) was added into the phosphate-bonded coating as a reinforcement to improve the tribological properties of the coating. In addition, the evolution of the physiochemical structure of CF before and after the modification was investigated by Fourier transform infrared spectroscopy, X-ray diffraction analysis, X-ray photoelectron spectroscopy, and scanning electron microscopy. The results show that GO and CF are chemically bonded together, and the CF surface becomes rough due to the presence of GO, enhancing mechanical engagement to improve the interfacial bond between CF-GO and the coating matrix, which is improved by the CF pull-out test. Tribological tests were conducted to investigate the wear behavior of the coating. The friction coefficient of the coating decreases with the increase of CF-GO. Besides, the wear rate of the coating shows similar trends with the addition of CF-GO. The addition of 15 wt % CF-GO has reduced the coefficient of friction and wear rate of the coating by approximately 18 and 40%, respectively, when compared to those of the coating without GO-CF. The related mechanisms are also clarified.