掺杂SiO_2气凝胶结构及其热学特性研究  

Structure and thermal properties of doped SiO_2 aerogels

作　　者：邓忠生[1] 张会林[1] 魏建东[1] 王珏[1] 沈军[1] 周斌[1] 陈玲燕[1] 

机构地区：[1]同济大学波耳固体物理研究所,上海200092

出　　处：《航空材料学报》1999年第4期38-43,共6页Journal of Aeronautical Materials

基　　金：国家自然科学基金!(59802007);863 基金!(863-416-3-9);启明星后基金!(98QME1406)

摘　　要：以正硅酸四乙酯为硅源，钛白粉为红外遮光剂，通过溶胶－凝胶及超临界干燥过程制备了钛白粉掺杂ＳｉＯ２ 气凝胶。用透射电镜、扫描电镜以及孔径分布仪对其结构进行了表征，并用动态热线法对其热学特性进行了测试。结果表明： 钛白粉能较均匀的分散在ＳｉＯ２ 气凝胶中；掺杂ＳｉＯ２ 气凝胶的孔洞大小分布在５～７０ｎｍ ，峰值在２０ｎｍ 附近，组成ＳｉＯ２ 网络的胶体颗粒为５～１０ｎｍ ；随着钛白粉掺杂量的增加，掺杂ＳｉＯ２ 气凝胶的孔径分布峰高变矮，同时出现孔径为几纳米的微孔；热学测试结果显示钛白粉掺杂量为２０ｗ ｔ％ 的ＳｉＯ２ 气凝胶在常压、８３１Ｋ 时的热导率为０．０３５ｗ ｍ － １Ｋ－ １。Nano porous TiO 2 doped SiO 2 aerogel insulation were prepared via sol gel process using tetraethoxysilane (TEOS) as the precursor and followed by ethanol supercritical drying. TEM, SEM and pore size distribution techniques were used to characterize the morphology and pore structure of the doped silica aerogels. The thermal conductivity measurement of the silica aerogels was determined using the transient hot wire technique. The results show that TiO 2 powders can be scattered homogeneously in the silica aerogels; the pore size of the TiO 2 doped silica aerogels is 5～70 nm, the average pore size (BJH) is about 20 nm and the size of the silica particles is 5～10 nm; the peak of the pore size distribution of the TiO 2 doped silica aerogels shortened with the increase of the TiO 2 powders while some pores less than several nm emerged and the thermal conductivity of the TiO 2 (20wt%)doped silica aerogel is 0.035 wm -1 K -1 at 831K and 1 atm.

关 键 词：SIO2气凝胶 掺杂 超临界干燥 热导率 气凝胶 

分 类 号：O648.17[理学—物理化学] TQ427.26[理学—化学]