Fabrication of SiC/SiC Composites Using both Chopped Fiber and a Hybrid Reinforcement of Chopped and Continuous Fibers

Chopped fiber and a hybrid reinforcement of chopped and continuous fibers were used for fabricating SiC/SiC composites. Under the selected sintering pressure, the composite sintered at lower temperature (1820°C) had lower density. Increasing temperature to 1850°C, the density of the composite reached at a higher level. However, pores still existed and mainly distributed in the areas the fibers accumulated, especially inside of the fiber bundles. Densely sintered matrix still could be found in the composite sintered at 1820°C, 15 MPa. In the areas with the fibers accumulated, matrix was relatively weak so that the cracks were easily propagated leading to the delamination during bending test. When continuous fiber was included into the chopped fiber reinforced composite, a hybrid reinforcing mechanism was obtained. This kind of composite had obviously improved toughness and strength. On the fracture surface, the pulled out fibers that were perpendicular to the fracture surface were increased.