Experimental Observations of High Fracture Resistance in Silicon Carbide/Alumina Laminated Composites

Model laminated composites were fabricated with porous-Al₂O₃ interfaces between SiC bars. The porous Al₂O₃ was deposited using an aerosol spray deposition technique, and the sandwich specimen was fabricated by hot pressing. Residual thermal stresses were present in the interface because of the difference in the coefficients of thermal expansion of SiC and Al₂O₃. Crack deflection was observed with measured interfacial fracture resistances that were considerably higher than the deflection threshold predicted by the He–Hutchinson criterion. Examination of the fracture surface revealed a tortuous crack path and significant crack–flaw interaction.