C/C-ZrC-HfC-SiC 复合材料组分调控及烧蚀行为

Ceramic matrix composites are one of the potential thermal protective materials due to their low density, good mechanical properties, excellent oxidation resistance and ablation resistance. However, with the increasing speed of advanced aircraft, the thermal structural components suffer severe ablation environment, the requirements of composites properties such as oxidation resistance and anti-ablation are also gradually increasing. Nevertheless, the relationship between the proportion of ceramic matrix components and the ablation property of composites is still not clarified, which limits the improvement of ablation properties for the composites. Therefore, in this paper, the carbon/carbon green body was prepared by chemical vapor infiltrate (CVI) process, and then mixed solutions with different ratios of silicon, zirconium and hafnium precursors were used as impregnating solution, and different proportions of C/C-ZrC-HfC-SiC composites with different ceramics proportions were prepared by precursor infiltration pyrolysis (PIP) process. The structural evolution of the composites before and after oxyacetylene ablation were analyzed by SEM, EDS and other methods. The effects of ceramics proportions of composites on thermo-oxidation ablation properties were studied and analyzed. The results show that the ablation property of the composites achieved optimal performance when the proportion of polycarbilane is 30%, and the proportion of zirconium and hafnium ceramic precursor is 35%, respectively. The superior ablation properties of the composites are attributed to the formation of an oxide film composed of molten SiO₂ and dispersed ZrO₂-HfO₂ particles, which decelerate the ablation.