| Popis: |
C/C-HfC composites with a density of 2.14 g/cm3 was successfully prepared using an inorganic hafnium solution as a precursor via chemical vapor infiltration (CVI) and precursor infiltration pyrolysis (PIP) methods, and its microstructure and composition were analyzed. The results show that the HfC ceramics are uniformly dispersed in the pores of the matrix and closely bonded to the matrix. The material's ablation resistance is significantly enhanced by introducing HfC ceramics. Under the same heat flux conditions, when the ablation time is 120 s, the linear and mass ablation rates of the C/C-HfC composite are 6.20×10-2 mm·s-1 and 2.03×10-2 g·s-1, respectively, which are reduced by 48.33% and 40.12%, respectively, compared to those of the C/C composite. During the ablation process, HfC would react with oxygen in the heat flux to generate molten HfO2, which uniformly covers the surface of the matrix to form a protective layer, isolates the heat flux, prevents oxidation of the matrix, and prevents heat transfer. The evaporation of molten HfO2 also takes away some of the surface's heat. With the increase of ablation time, the loss of HfO2 will gradually increase, the protective layer on the surface of the matrix will be gradually destroyed, and the ablation damage of the heat flux on the matrix would become more severe. |
