Microstructures and ablation properties of C/C-SiC-ZrC composites prepared using C/C skeletons with various densities

Two-dimensional C/C-SiC-ZrC composites were prepared by isothermal chemical vapour infiltration combined with the reaction melt infiltration method using various density porous C/C skeletons. The microstructures, mechanical properties and ablation behaviour of the C/C-SiC-ZrC composites were systematically studied. The results showed that the strength and ablation resistance of C/C-SiC-ZrC composites improved with the increase of the C/C skeleton density. When the density of the C/C skeleton was 1.51 g/cm³, the bending modulus and strength of the composites were 13.19 GPa and 70.57 MPa, respectively, and the linear and mass ablation rates of the composites ablated for 90 s were 1.44×10^-3 mm/s and 0.21×10^-3 g/s, respectively. These properties were attributed to the introduction of ZrC and SiC into the matrix and the formation of a dense SiC-ZrC coating on the surface. The SiC-ZrC coating acted as an oxygen diffusion barrier for C/C composites and first reacted with oxygen to form an oxide protecting layer in the ablation environment.