Mechanical Properties of Whisker-Reinforced Cordierite Glass Matrix Composites

The development of a whisker-reinforced ceramic matrix composite has been shown to be a reasonable method of achieving improved mechanical properties for ceramic materials. In this work a cordierite matrix was reinforced with 20vol% of silicon carbide whiskers. The mechanical properties of this composite were compared to those of the nonreinforced cordierite matrix. As would be expected, the whisker- reinforced matrix showed a significant improvement in mechanical properties. The specimens used for testing were processed by hot-pressing in an argon atmosphere using a graphite die coated with boron nitride. Hot pressing was carried out at 950°C for the pure matrix and 1050°C for the SiC-reinforced matrix; a pressure of 6.9 MPa was used in all cases. After pressing to full density, the glass was then heat treated to attain proper recrystallization. The specimens were then cut into rectangular bars and tested for ultimate strength and fracture toughness (KIC). The pure cordierite matrix was found to have an average ultimate strength and KIC of 84 GPa and 5.0 MPa·m1/2, respectively. The SiC whisker-reinforced matrix had an ultimate strength and KIC of 161 GPa and 7.0 MPa·m1/2, respectively