MECHANICAL-BEHAVIOR OF ALUMINA REINFORCED WITH CARBON-COATED SILICON-CARBIDE WHISKERS

SIC whiskers with 0, 20, and 50 Angstrom carbon coatings were incorpor ated into an alumina matrix to modify residual thermal stress and inte rfacial bonding. Composites mere characterized using triaxial X-ray di ffraction for residual stress determination and electron microscopy to explore interfacial chemistry, Fracture toughness and R-curve behavio r were examined for short and long crack lengths. Uncoated SiC whisker s optimized strength, fracture toughness, and R-curve behavior of thes e composites. A graphite interphase at the whisker/matrix interface de creased contributions to crack bridging without promoting additional t oughening by whisker pullout.