Microstructure and mechanical properties of C/C–SiC composites fabricated by a rapid processing method

C/C–SiC composite was fabricated with time efficiency and low cost by a two-step process. A quasi 3D carbon-fiber-felt was firstly densified to C/C composite in 2–5 h by a thermal gradient CVI method based on precursor of kerosene. Then, the C/C composite of different porosities was reactively infiltrated with Si for 40 min to obtain C/C–SiC composite. The influence of the porosity of the C/C composite on the microstructure and mechanical properties of the C/C–SiC composite was investigated. The results show that the density of the C/C–SiC composite increases from 2.0 g/cm3 to 2.3 g/cm3 while its porosity decreases from 5.8% to 1.7% with the increasing porosity of the C/C composite. Moreover, the porosity of the C/C composite affects both the amounts of β-SiC, Si phases and the mechanical properties of the C/C–SiC composite. The flexural strength and modulus of the C/C–SiC composite are much higher than those of the C/C composite. The C/C–SiC composite from the C/C composite of 19.7% porosity has the highest flexural strength and modulus, which are 132 MPa and 14.4 GPa, respectively.