In situ growth, microscopic morphologies, and oxidation resistance of SiO2 and TiO2 on the surface of carbon fiber-reinforced composites

Carbon fiber-reinforced composites (CFRCs) as the load-bearing structural component are widely used in the military and industrial fields. However, CFRCs undergo the severe oxidation in high-temperature oxygen environments, seriously affecting their service safety. In current work, SiO 2 and TiO 2 coatings are selected to synthesize on the CFRCs surface for improving their anti-oxidation by a liquid-phase deposition technique. The deposition technique is simple, controllable, and reproducible. The formation process, microscopic morphologies, chemical bonding, and molecular structure of SiO 2 and TiO 2 on the CFRCs surface are systematically investigated. A series of characterizations, namely X-ray diffractometry, Raman spectrum, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, demonstrate that SiO 2 and TiO 2 coatings are successfully synthesized on the surface of CFRCs, respectively. The scanning electron microscopy and elemental distribution show that CFRCs are evenly loaded with SiO 2 or TiO 2 particles on the surface. TiO 2 particles grow faster and the synthesized particles are finer with the particle diameter of 200 ~ 300 nm in comparison with 400 ~ 500 nm of SiO 2 particles, under the same synthesis conditions. In addition, an isothermal oxidation test is conducted for the CFRCs modified by SiO 2 or TiO 2 at 1273 K for 30 min. The weight loss rate of modified composites is lower than 62.12% of bare sample. Among them, the composites modified by SiO 2 or TiO 2 at 70 °C for 3 h possess the lowest weight loss rate of 34.24 and 37.32%, respectively, indicating that the modification of SiO 2 and TiO 2 all can improve the oxidation resistance of CFRCs. Graphical abstract