TAILORED COATINGS FOR GR/TIAL COMPOSITES FOR HIGH TEMPERATURE STRUCTURES

THE INNOVATION WE PROPOSE IS A NOVEL PRECERAMIC POLYMER ROUTE TO THIN (< 1U) COATINGS OF NITRIDES AND CARBIDES ON GRAPHITE FIBERS TO BE USED IN TITANIUM ALUMINIDE INTERMETALLIC COMPOSITES. IF SUCCESSFUL, THE COATINGS WILL PROVIDE AN EFFECTIVE BARRIER TO FIBER-MATRIX REACTION AT HIGH PROCESSING AND SERVICE TEMPERATURES - A MAJOR CAUSE OF DEGRADATION IN THESE NEW HIGH TEMPERATURE COMPOSITES. THE COATINGS WILL ALSO PROVIDE A MEANS TO TAILOR THE INTERFACE AND THEREBY TOUGHEN BRITTLE MATRIX COMPOSITES. THE PRECERAMIC POLYMER ROUTE WILL UNIFORMLY COAT INDIVIDUAL FILAMENTS IN A CONTINUOUS, MULTIFILAMENT TOWS AT RELATIVELY LOW COST. ALSO, THIS APPROACH IS ADAPTABLE TO A VARIETY OF FIBERS, MATRICES, AND COATINGS.