Pinning Effect of SiC Particles on Mechanical Properties of Al₂O₃-SiC Ceramic Matrix Composites

The fracture mechanical properties of SiC particle reinforced Al₂O₃ matrix composites were investigated at room temperature and T= 1200°C. The results showed that the fracture strength and toughness of composites are enhanced, compared with those of monolithic Al₂O₃, especially at elevated temperature, and the strength and toughness of composites increase with the increase in the content of SiC particles. It was found that the improvement in fracture mechanical properties of composites is due to the fracture mode transformation from intergranular in monolithic Al₂O₃ to transgranular in the composites, and the fracture mode change might result mainly from the pinning effect of SiC particles on the Al₂O₃ boundaries. The study on flexure creep behavior of monolithic Al₂O₃ and the composites with 20 vol% SiC particles at T = 1260°C indicated that the composites also exhibited some improvement in their creep resistance, compared to the creep behavior of monolithic Al₂O₃, due to the pinning effect of SiC particles at Al₂O₃ grain boundaries on grain boundary sliding during creeping.