Effects of hot pressing condition on the properties of SiCf/SiC composites

Abstract

Continuous SiC fiber-reinforced SiC-matrix composites (SiCf/SiC) had been fabricated by electrophoretic infiltration combined with ultrasonication. Nano-sized βSiC added with 12 wt% of Al2O 3-Y2O3 additive and Tyranno TM -SA3 fabric were used as a matrix phase and fiber reinforcement, respectively. After hot pressing at 5 different conditions, the density, microstructure and mechanical properties of SiCf/SiC were characterized. Hot pressing at relatively severe conditions, such as 1750 °C for 1 and 2 h, resulted in a brittle fracture behavior due to the strong fiber-matrix interface in spite of their high flexural strength. On the other hand, toughened SiCf/SiC composite could be achieved by hot pressing at milder condition because of the formation of weak interface in spite of the decreased flexural strength. These results proposed the importance of weak fiber-matrix interface in the fabrication of ductile SiCf/SiC composite.