溶胶凝胶法制备SiO_2气凝胶/纤维复合材料及其性能的表征

CHARACTERIZATION OF SiO_2 AEROGELS/FIBER COMPOSITES PREPARED BY THE SOL-GEL METHODS

以正硅酸乙酯(TEOS)为前躯体,采用溶胶-凝胶工艺制备氧化硅溶胶,将其与无机陶瓷纤维预置体在常温下复合干燥后得到SiO2气凝胶隔热复合材料。利用扫描电子显微镜(SEM)对样品微观结构进行分析,利用热平板法对材料的热学性能进行表征,分析了氧化硅气凝胶隔热复合材料隔热机理。研究表明:采用溶胶凝胶工艺和真空技术,气凝胶充分填充在纤维预置体的空隙中,可以制得低导热系数、低热扩散系数和低比热容的SiO2气凝胶/纤维复合材料,导热系数为0.06815W/mK,热扩散系数为0.2677mm2/s,比热容为0.2919MJ/m3K。

SiO2 aerogels/fiber composites were prepared by sol-gel process and drying under ambient pressure using tetraethoxysilane（TEOS） as precursor,chlorhydric acid and hartshorn as catalysts,and ceramic fiber preform as reinforcement.The microstructures were characterized by scanning electron microscope（SEM）,and the thermal properties were tested by hot plate method.The mechanisms of thermal properties of SiO2 aerogels/fiber composites were analyzed.The results show that,SiO2 aerogels/fiber composites with the properties of low thermal conductivity,low thermal diffusivity,low thermal capacity can be prepared by Sol-Gel process and vacuum technology,the inner space of the fiber preform was filled with SiO2 aerogels,the thermal conductivity of the composites can reach 0.6815W/mK,while the thermal diffusivity was 0.2677mm^2/s,and the thermal capacity was 0.2919MJ/m3K.