Fabrication of SiC fiber reinforced SiC composite by chemical vapor infiltration for excellent mechanical properties

The process optimization for the forced-flow/thermal gradient chemical vapor infiltrated SiC based composites with an advanced SiC fiber(Tyranno SA) was carried out. The new SiC/SiC composites had a lower porosity and the uniform distribution of pores compared with conventional CVI. The uniform interphases between SiC fibers and matrix could be obtained by reversing the gas-flow direction mid-way through the coating process. The tensile strength was slightly increased with the thickness of carbon interphase in the range of 20-250 nm. It was found that the fabric layer orientation and multilayer SiC/C interphase were very effective to improve the mechanical properties.