Oxide aluminum coatings by the sol-gel method on carbon fibers

The Al₂O₃ coatings were deposited on PAN carbon fibers with a sol-gel method. A sol-gel solution was prepared using an aluminum isoproxide precursor. The antioxidant properties of the barrier coatings on the surface of carbon fibers were studied at high temperatures. The coating protects well the carbon fibers up to an annealing temperature of 700 °C. The properties of the coating appear to be worse at an annealing temperature of 800°C and higher, which leads to the loss of the weight of the fiber. The burnout rate of carbon fiber without coating increases with an increase in annealing temperature compared to those with Al₂O₃ coating. The coating slows down the oxidation of carbon fibers due to the isothermal oxidation of Al₂O₃.