FIBER COATINGS FOR SIC-FIBER-REINFORCED BMAS GLASS-CERAMIC COMPOSITES

Interfaces in SiC-fiber-reinforced glass-ceramic matrix composites wer e modified by applying different coatings to the fibers and varying th e coating thickness, Coatings of SIC/BN, Si3N4/BN, and BN were applied to the fibers by CVD prior to composite fabrication, Interfacial micr ostructures mere characterized using high-resolution and analytical tr ansmission electron microscopy, Oxidation of the SIC fibers during com posite fabrication was suppressed by the fiber coatings, provided that the coatings were sufficiently thick to prevent oxygen diffusion from the matrix, The SiC/BN and BN coatings were stable during high-temper ature exposures, while the Si3N4/BN coating underwent chemical reactio ns.