Processing and microstructure of silicon carbide fiber-reinforced silicon carbide composite by hot-pressing

Continuous 2D woven fiber-reinforced SiC composites were fabricated by hot-pressing in Ar at 1750 C under a pressure of 40 MPa using Al-B-C or Al2O3-Y2O3-CaO system as sintering additives. In this study, fracture behavior and microstructure of the composites fabricated by this process were investigated. These composites achieved nearly full density in both cases. In the case of the composite with Al-B-C additives, the load-displacement behavior of the composite with non-coated Hi-Nicalon cloths showed completely brittle fracture, whereas that of the composite with BN-coated Hi-Nicalon cloths showed ductile fracture with a lot of fiber pull-out. On the contrary, in the case of the composite with Al2O3-Y2O3-CaO additives, the load-displacement behavior of the composite with non-coated Hi-Nicalon cloths showed slight ductile fracture with small tails, whereas that of the composite with BN-coated Hi-Nicalon cloths showed completely brittle fracture. (orig.)