Preparation of anti-oxidative SiC/SiO2 coating on carbon fibers from vinyltriethoxysilane by sol–gel method

The anti-oxidative SiC/SiO2 coating was prepared on carbon fibers by a sol–gel process using vinyltriethoxysilane (VTES) as the single source precursor. The derived coating was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The oxidation resistant properties of the carbon fiber with and without coating were studied by isothermal oxidation. The results indicated that the carbothermal reduction reaction led to the decrease of SiO2 phase and the increase of SiC phase at 1500 °C. The uniform SiC/SiO2 coating prepared from a sol concentration of 4 wt% and heat treated at 1500 °C showed the optimal oxidation resistant property. The oxidation resistance of the carbon fiber was improved by the SiC/SiO2 coating, and the oxidation activation energy was increased by about 23% as compared with uncoated carbon fiber.