A new barrier coating for protection of continuous SiC fibers in composites up to 1500C will be applied to continuous fiber tows by chemical vapor deposition (CVD) in commercial apparatus. Current SiC fibers, and currently used BN barrier coatings, are restricted to use below 1100C and are unsuitable for use in turbine combustors and other high temperature applications. Two CVD compositions in the BN/TiN system and two compositions in another system. Interfacial shear properties, oxidation and moisture resistance, thermal expansion coefficients and chemical analyses will be obtained on well defined bulk SiC before coating continuous tows. Average coating thickness, coating uniformity and textile handling behavior of the coating systems will be evaluated before selecting a preferred system to be scaled up in Phase II.
