硅酸铝纤维增强SiO_2气凝胶复合材料的力学与隔热性能研究

THE MECHANICAL PROPERTIES AND THERMAL-INSULATING PERFERMANCE OF SiO_2 AEROGEL COMPOSITES REINFORCED WITH ALUMINOSILICATE FIBER

SiO_2气凝胶由于其独特的纳米多孔结构而具有优异的保温隔热性能,但其力学性能较差限制了其在很多工业领域内的应用。以硅酸铝纤维作为增强材料,采用溶胶凝胶法以及常压干燥法制备出完整的块状硅酸铝纤维/SiO_2气凝胶复合隔热材料,并分别用电子万能试验机、SEM、热导率测试仪、BET等检测方法表征了该复合隔热材料的性能。结果显示,纤维的加入提供了一种新的能量消耗机制,硅酸铝纤维/SiO_2气凝胶复合隔热材料的力学性能明显优于纯气凝胶材料。该复合材料的比表面积和平均孔径分别为383.5 m2/g和8.4 nm,孔隙率高达87%,是典型的介孔材料,热导率低至0.02 W/(m·K)~0.04W/(m·K),具备良好的保温隔热性能。

SiO2 aerogels have outstanding performance in quality of heat insulation and preservation for its nanoporous microstructure. However,the poor mechanical properties of SiO2 aerogels restrict its application in many industrial fields. In this paper,aluminosilicate fiber is used as reinforcement to strength the skeleton of SiO2 aerogels,and a kind of aluminosilicate fiber/SiO2 aerogels composites was prepared by sol-gel method and atmospheric pressure drying. The microstructure and properties of the composites are characterized by SEM,universal testing machines,thermal conductivity meter and BET. The results indicate that the adding of aluminosilicate fiber provide a new energy expenditure mechanism for the composites under applied force,and the mechanical property of the composites are increased efficiently. The surface area and average pore diameters of the composites are 383. 5 m^2/g and8. 4 nm,respectively,and the porosity is 87%,belonging to typical mesopore material. At the same time,the thermal conductivity of composites is as low as 0. 02 W/（m·K） - 0. 04 W/（m·K）,indicating their good thermal-insulating performance.