LaB6改性C/C-ZrC-SiC复合材料的制备及其抗烧蚀性能

Preparation and Ablation Properties of LaB6 Modified C/C-ZrC-SiC Composites

摘要:

采用料浆浸渍结合树脂浸渍裂解法制备了含9.73 wt.% LaB6的LaB6-C/C预制体，再利用反应熔体浸渍法（RMI）制备了LaB6改性C/C-ZrC-SiC复合材料，考察了材料的微观结构和烧蚀行为，探究LaB6对材料抗烧蚀性能的作用机理。结果表明：在热流密度为2380 kw/m2的氧乙炔焰烧蚀120 s后，LaB6改性C/C-ZrC-SiC复合材料的质量烧蚀率和线烧蚀率分别为1.05×10-3 g/s和2.17×10-3 mm/s，较未改性C/C-ZrC-SiC复合材料分别降低了74.8 %和61.9 %。烧蚀过程中，LaB6发生氧化反应生成La2O3和B2O3，La2O3与ZrO2之间的固溶作用以及化学反应，再加之液态B2O3具有促进固相反应传质的作用，使得材料表面形成大面积连续稳定的ZrO2-La2Zr2O7-La0.1Zr0.9O1.95熔融态保护层，这是材料优异抗烧蚀性能的主要原因。

Abstract:

LaB6-C/C preform containing 9.73% wt.% LaB6 was prepared by slurry impregnation combined with resin infiltration pyrolysis, and then LaB6 modified C/C-ZrC-SiC composites were obtained by reactive melt impregnation (RMI). The microstructure and ablative behavior of the composites were studied, and the mechanism of LaB6 on the ablation properties of the composites were investigated. The results show that, after oxyacetylene ablation at the heat flux of 2380 kw/m2 for 120 s, the mass ablation rate and linear ablation rate of LaB6 modified C/C-ZrC-SiC composites are 1.05×10-3 g/s and 2.17×10-3 mm/s, which are 74.8 % and 61.9 % lower than those of unmodified C/C-ZrC-SiC composites, respectively. During ablation, LaB6 is oxidized to La2O3 and B2O3. The solid solution and chemical reaction between La2O3 and ZrO2, coupled with the effect of liquid B2O3 to promote mass transfer in solid phase reaction, make the surface of the material form a large area of continuous and stable ZrO2-La2Zr2O7-La0.1Zr0.9O1.95 molten protective layer, which is the main reason for the excellent ablation performance of the material.