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以短切石英纤维、硅溶胶、B4C粉烧结制备多孔刚性骨架,以正硅酸乙酯、去离子水和乙醇配制SiO2溶胶,多孔骨架浸渍SiO2溶胶后经超临界干燥制备了SiO2气凝胶/多孔骨架复合材料。对隔热瓦的高温热导率、比表面积和孔径分布进行了测试并且观察了微观形貌。结果表明:SiO2气凝胶复合的石英纤维刚性隔热瓦具有纳米孔结构,平均孔径为39.5nm,在600℃和800℃,其热导率分别仅为0.0335W/(m.K)和0.0404W/(m.K),与未复合气凝胶的刚性骨架相比,高温热导率下降了40%～50%。此外,SiO2气凝胶填充了隔热瓦骨架中的大部分的宏孔,抗弯强度提高了30%,并且使刚性隔热瓦的脆性有一定改善。
A porous rigid skeleton was prepared by sintering of chopped quartz fiber, silica sol and B4C powder. SiO2 sol was prepared by using tetraethoxysilane, deionized water and ethanol. SiO2 porous gel was impregnated with porous silica sol and dried by supercritical fluid. Porous skeleton composite. The high temperature thermal conductivity, specific surface area and pore size distribution of the insulation tile were tested and the microscopic morphology was observed. The results show that the silica airgel composite quartz thermal insulation tile has a nano-pore structure and an average pore diameter of 39.5nm. At 600 ℃ and 800 ℃, its thermal conductivity is only 0.0335W / (mK) and 0.0404W / (mK), the thermal conductivity at high temperature is reduced by 40% to 50% compared to the rigid skeleton of the non-composite airgel. In addition, SiO2 aerogels fill most of the macropores in the thermal shield’s framework, increasing the flexural strength by 30% and improving the brittleness of the rigid thermal shield.