Investigation of in-situ microstructural mechanical properties and thermal damage mechanisms of SiC_f/SiC under CVI and PIP processes

This study compared the in-situ microstructural mechanical properties of SiC_f/SiC composites fabricated by CVI and CVI + PIP process. The investigation revealed that the degree of fiber damage caused by PIP process was 13.8 % before oxidation and 21.9 % after oxidation. TEM was employed to compare the oxidation thickness and element distribution of two processes. The results indicated that external oxygen exhibited longitudinal infiltration oxidation, whereas PIP process introduced oxygen into the material, causing the internal oxygen to diffuse the oxidation process horizontally. As a result of the joint action of internal and external oxygen, the material ultimately exhibited a uniformly oxidized state.