Influence of CuSO4 Doping on the Oxidation Resistance of TiO2-Coated Carbon Fibers

Carbon fiber (CF) was coated with TiO2 layer by sol-dipping method using CuSO4 as dopant. The prepared samples were characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). The SEM/TEM results show that the prepared CuSO4-TiO2 layer is uniformly and compactly. The thickness of the coating layer is increased from 45 nm to 185 nm. XRD results show that prepared layer is composited by anatase TiO2. The oxidation resistant properties of the carbon fibers were studied using isothermal oxidation experimental. Compared with TiO2 coated carbon fiber, the complete decomposition temperature of the CuSO4-TiO2 coated carbon fiber is increased from 667 degrees C to 800 degrees C. The oxidation activation energy of TiO2 coating carbon fiber and CuSO4-TiO2 coating carbon fiber are 118.390 kJ . mol(-1), 152.562 kJ . mol(-1), respectively. The improvement of oxidation resistant of the CuSO4-TiO2 coated carbon fiber is attributed to the CuSO4 liquid sinter effect on the TiO2 layer.