Research Of Surface Treatment And Coatings On Mosophase Pitch-Based Carbong Fibers

Carbon fiber and Carbon fiber reinforced composite materials have many Excellent performance, such as high strength, high modulus, temperature resistance, corrosion resistance, fatigue resistance, creep resistance, electrical conductivity, heat transfer, and small specific weight. In this paper, the mesophase pitch-based carbon fiber was treated by the electrochemical oxidation, and prepared Ta, Zr coatings on the surface of treated carbon fiber by sol-gel method to enhance the temperature resistance and oxidation resistance of the mesophase pitch-based carbon fiber, the study contents and results as follows:1. The mesophase pitch-based carbon fiber was treated by the electrochemical oxidation. The oxygen-containing functional groups and microstructures of carbon fiber were studied by FT-IR, XPS and SEM. Results showed that:The oxygen-containing functional groups on the surface of mesophase pitch-based fiber increased significantly after electrochemical oxidation, and the most is hydroxyl, which improved to the most at the oxidation current of 0.7A, oxidation time for the 150s, and the general oxygen-containing functional groups increased by 9.5%. The results also showed that oxidation time and oxidation current have equivalence effect.2. Zirconium and Tantalum coatings were prepared on the surface of mesophase pitch-based carbon fiber by sol-gel method. The functional groups of sol-gel were analyzed by FT-IR, the microstructures, phase composition and oxidation behavior of coated carbon fiber were studied by XRD, SEM, and TG. The results showed that:Zirconium coatings were prepared on the surface of carbon fiber, after 1000℃heat treatment, the ZrO2 coatings are consecutive, complete, compact, no crack and porosity, the initial oxidation temperature of coated fibers is about 160℃higher than uncoated carbon fibers, no significant weight loss below in 700℃, and termination oxidative temperature improve to 770℃; Tantalum coatings were prepared on the surface of carbon fiber, after twice coated and 1600℃heat treatment, coatings are continuous, uniform, fine smoothness, and no big holes, the thickness is about 150nm, the initial oxidation temperature of the twice coated carbon fibers is about 250℃higher than that of uncoated carbon fibers, and below in 800℃, there have no obvious weightlessness, the final oxidation temperature also improve to 870℃. Add dimethylacetamide and heating rates by 1℃/ min are benefit for format dense coating.