Preparation and microstructure of Al2O3–SiO2–TiO2 coating on three-dimensional braided carbon fiber by sol–gel technology

Abstract

Al2O3–SiO2–TiO2 coatings were synthesized on the surface of three-dimensional (3-D) braided carbon fiber by the sol–gel method. The Al2O3–SiO2–TiO2 coating was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The effect of immension–pyrolysis cycle, immension time and heat treatment temperature on the microstructures and phase composition of the coating was investigated. The mechanical properties of the carbon fiber coated with various coating thickness were also measured. The results showed that the good morphology of the coating obtained was use of heat treatment at 750°C for 2 immension–pyrolysis cycles by the immersion time of 40min per cycle. The thickness was about 150–1200nm along with the increase of immersion time from 40 to 120min. Tensile strength measurement revealed that the Al2O3–SiO2–TiO2 coated carbon fiber maintained 96.8% of its original strength when the thickness of the coating was 470nm.