Mechanical and ablative properties of C/C composites modified by SiC using liquid silicon infiltration method

SiC modified C/C (C/C-SiC) composites were prepared through incorporating SiC matrix into porous C/C composites using liquid silicon infiltration method. The porous C/C composites with a density of 0.96, 1.31, 1.50, 1.68, and 1.81 g/cm³ were produced by a sequent processing of isothermal chemical vapor infiltration and polymer impregnation and pyrolysis using carbon fiber needled felts as the preforms. The initial density of the preforms was 0.56g/cm³. The mechanical and ablative properties of C/C-SiC composites were investigated using three-point flexural testing and oxyacetylene torch flame. Results show that C/C-SiC composites possess excellent ablation resistance and can be used in the ablation environment of 2100°C for long time, compared with C/C composites. The composites with the density of 2.00g/cm³ exhibit relatively superior mechanical and ablative properties, which is prepared from the porous C/C composites of the density 1.81g/cm³. The corresponding flexural strength of the composites reaches 142.6MPa under room temperature, while the mass ablation rate is 0.6×10^-4g/s under the ablation temperature of 2100°C holding for 600s.