Microstructure, mechanical properties and reaction mechanism of KD-1 SiCf/SiC composites fabricated by chemical vapor infiltration and vapor silicon infiltration

Three-dimensional (3D) KD-1 silicon carbide fiber reinforced silicon carbide matrix (KD-1 SiCf/SiC) composites were fabricated by a combining chemical vapor infiltration (CVI) and vapor silicon infiltration (VSI) process. The microstructure and mechanical properties of the resulting KD-1 SiCf/SiC composites were studied. The results show that the resulting SiCf/SiC composites have high bulk density and low open porosity (<6%). The mechanical properties of the resulting SiCf/SiC composites firstly increase and then decrease with decreasing the open porosity of the SiCf/C composites. The KD-1 SiC fibers were not severely deformed and adhered to the matrix with a weak interface during the VSI process. As a result, the composites exhibit non-catastrophic failure behavior. Additionally, the diffusion mechanism for the VSI process was also investigated in our work.