STRENGTHENING/TOUGHENING OF LAMINATED (SiCw+SiCp)/SiC CERAMIC COMPOSITES

Laminated (SiCw+SiCp)/SiC ceramic composites with different ratios and contents of SiC whiskers and SiC particles were fabricated by tape casting and chemical vapor infiltration (CVI), and the strengthening/toughening mechanisms of the composites were investigated. The ratio of SiC whiskers and SiC particles had significant effect on the relative density and mechanical properties of the composites. The flexural strength and tensile strength reached the highest value of 333 MPa and 152 MPa with the ratio of 4, and the fracture toughness reached the highest value of 7.63 MPa. m(1/2) with the ratio of 3. The mechanical properties were also dependent on the total content of reinforcements. By maintaining a constant ratio of SiC whiskers and SiC particles, the mechanical properties were increased with increasing contents of reinforcements. The properties of the composites can be improved dramatically by an appropriate ratio of SiC whiskers and SiC particles, owing to their cooperative effect in densification and reinforcement.