采用溶胶-凝胶工艺在常压下制备了SiO₂气凝胶薄膜,并用傅里叶红外光谱仪(FTIR)、扫描电子显微镜(SEM)、椭偏光谱仪等表征了薄膜的结构和性能.研究结果表明,气凝胶薄膜的折射率低达1.067,对应孔洞率为87.7%,密度为0.269×103kg·m-3,热导率为0.020W·m-1·K-1(300K)时,介电常数为1.52.这些优异性能的获得,主要归因于酸/碱两步催化、溶剂替换以及胶粒表面硅烷化等三个过程.

Silica aerogel thin films were prepared at ambient pressure by sol gel technique. Fourier transform infrared spectroscope(FTIR), scan electron microscope(SEM) and ellipsometer were used to characterize the structure and properties of the films. The refractive index of the resultant aerogel films is as low as 1.067, which corresponds to the porosity of 87.7 %, the density of 0.269×10 3 kg·m -3 , the thermal conductivity of 0.020W·m -1 ·K -1 (at 300K), and the dielectric constant of 1.52, These excellent properties mainly attribute to two step acid/base catalysis and the solvent exchange as well as the silylation on the surfaces of colloidal particles.