Experimental observations of high fracture resistance in silicon carbide/alumina laminated composites

Model laminated composites were fabricated with porous-Al2O3 interfaces bet ween SiC bars. The porous Al2O3 was deposited using an aerosol spray deposi tion technique, and the sandwich specimen was fabricated by hot pressing. R esidual thermal stresses were present in the interface because of the diffe rence in the coefficients of thermal expansion of SiC and Al2O3. Crack defl ection was observed with measured interfacial fracture resistances that wer e considerably higher than the deflection threshold predicted by the He-Hut chinson criterion. Examination of the fracture surface revealed a tortuous crack path and significant crack-flaw interaction.