Mechanical Properties of Silicon Carbide Whisker/Aluminum Oxide Matrix Composites

The mechanical properties of two SiC whisker/Al2O3 matrix composites were investigated as a function of whisker type. Composites were produced with both Silar-SC-9 and Tateho-SCW-1-S whiskers. The composites produced with the Silar-SC-9 whiskers exhibited a fracture strength of 641 MPa and a fracture toughness of 8.7 MPa·m1/2. The composites produced with the Tateho-SCW-1-S whiskers exhibited a comparable fracture strength of 606 MPa and a reduced fracture toughness of 4.6 MPa·m1/2. Transmission electron microscopy examination of the whisker/matrix interfacial regions indicated that no significant chemical reactions had taken place in either composite during processing. Scanning electron microscopy examination of the fracture surfaces revealed limited whisker puttout for the composites produced with the Silar-SC-9 whiskers and no evidence of whisker pullout for the composites produced with the Tateho-SCW-1-S whiskers. Analysis of toughening mechanisms indicated that whisker bridging and pullout processes may contribute to the enhanced fracture toughness for the composites produced with the Silar-SC-9 whiskers.