SILICON CARBIDE COATINGS FOR HIGH TEMPERATURE APPLICATION OF CARBON FIBERS

CARBON AND GRAPHITE FIBERS HAVE RELATIVELY POOR OXIDATION RESISTANCE. THEIR UTILITY IN HIGH TEMPERATURE APPLICATIONS CAN BE ENHANCED BY A WELL ADHERING OXIDATION RESISTANT COATING. SUCH COATINGS ALSO HAVE THE POTENTIAL FOR IMPROVING INTERFACIAL ADHESION WITH MATRIX RESINS. THE GOAL OF THIS PROGRAM IS TO DEMONSTRATE THAT A SIC COATING CAN BE APPLIED TO CARBON FIBERS WITH A SUFFICIENTLY STRONG BOND AT THE INTERFACE TO INSURE SURVIVAL AND TO ACT AS AN OXIDATION BARRIER. THE APPROACH IS TO CHEMICALLY MODIFY THE FIBER SURFACE TO FORM COVALENT BONDS WITH A POLYMERIC SIC PRECURSOR THAT IS THEN PYROLYTICALLY CONVERTED TO AN ADHERENT SIC COATING.