Fabrication and characterization of SiC whisker reinforced reaction bonded SiC composite

Abstract

SiC whisker reinforced reaction bonded SiC composites have been developed for fabricating large scale, complex shaped structural components. Here the composites were prepared with the method of slip casting and liquid silicon infiltration at 1650°C. The distribution, morphology and reinforcing behaviors of the SiC whisker in the composite were investigated. It is revealed that the introduction of SiC whisker increases the porosity of the green body, and accordingly the bulk density of the composite. Whisker pullout can be clearly observed on the fracture surface, implying a moderate bonding strength between the whisker and matrix. After liquid silicon infiltration, the SiC whisker keeps its initial diameter and morphology in the case of 15wt% whisker. The fracture toughness is enhanced by SiC whisker, reaching the peak value of 4.2MPam1/2 at the whisker fraction of 20wt%. Whisker pullout, whisker bridging and crack deflection are considered as the main toughening mechanisms.