以正硅酸乙酯为先驱体,采用溶胶-凝胶工艺制备SiO2溶胶,将其与Al2O3纤维复合,经超临界流体干燥技术制得SiO2气凝胶复合绝热材料.采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、压力试验机、平板导热仪等测试手段对样品的微观形貌、抗压强度以及热导率等进行了研究.讨论了材料的绝热机理,并对进一步降低SiO2气凝胶热导率的途径进行了概述.结果表明:添加Al2O3纤维能够明显增强SiO2气凝胶的综合力学性能；经过1000℃热处理的复合材料仍保持SiO2气凝胶的纳米多孔结构,这赋予复合材料优异的绝热特性.当Al2O3纤维添加量为8％(质量分数)左右时,可使复合材料同时具有较低的热导率(λ=0.051 W/(m·K),298 K)和较高的抗压强度(δbc=1.977 MPa).%SiO2 aero-gels thermal insulation composites were prepared by sol-gel technique and supercritical drying process, which using tetraethoxysilane as precursor and alumina fiber as reinforcement. The microstructure, compressive strength and thermal conductivity were characterized by transmission electron microscope (TEM), scanning electron microscope(SEM), compression testing machine and flat-plate thermal conductivity meter, etc. The thermal insulation mechanism of SiO2 aero-gels composites reinforced by Al2O3 fiber was discussed,and the approaches of further reducing thermal conductivity of SiO2 aero-gels were summarized. The results show that alumina fiber adding can increase the compressive strength of SiO2 aero-gels composites significantly. SiO2 aero-gels composites still retain the nano-porous structure after thermal treatment at 1000 ℃ which gives excellent thermal insulation properties of the composites. Both the low thermal conductivity (λ = 0. 051 W/(m · K), 298 K) and high mechanical strength (σbc = l. 977 MPa)are obtained while the adding quantity of Al2O3 fiber is about 8wt%.
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