碳气凝胶的制备研究

气凝胶是由纳米量级超细粒子或高聚物分子聚结构成的多孔性轻质固态材料 ,它在声学、光学、电学、动力学和低温热学等方面具有独特性质 ,因此受到多方面研究者的重视 1～ 4 ] .碳气凝胶最先是由 Pekala等 5] 在 80年代末研制成功的 ,其突出特点是网络连续 ,电导率高 ,孔洞微小且相互贯通 ,比表面大 ,密度变化范围大 ,是制造高性能电容器和电池的新一代理想材料6 ,7] .这种材料的低温电导率随温度连续单调变化 ,在一定温区范围内 ( <1 0 0 K)其电阻温度敏感度远大于传统的掺碳玻璃、锗以及其它金属电阻温度计材料 ,可望成为一种理想的低…

Studies on Preparation of Carbon Aerogels

Anew method for preparing carbon aerogels by using starch as a starting material through sol gel process, followed by supercritical drying and pyrolysis is described. The resulting aerogels which consist of irregular carbon particles with sizes about 20 nm were of uniform sizes, low density, porous monolithic materials with a bulk density of 108 kg·m^-3 and an electrical conductivity of 1.6 S·cm^-1 . The regular arranging crystal structure in manometer dimensions was observed by using high-resolution transmission electron microscopy and electron diffraction. The results of DTA-TG studies indicated that when starch aerogels were heated, the carbon aerogels with graphite structure formed through dehydration, pyrolysis and subsequent phase transition.