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采用正硅酸乙酯和二甲基乙氧基硅烷为原料,通过溶胶-凝胶、超临界干燥、1200℃裂解,制备纳米多孔的块状Si-C-O气凝胶。用TG-DTA、SEM和NMR考察Si-C-O气凝胶的化学成分和结构。结果显示,1200℃裂解之后,气凝胶由白变为黑色:密度为0.3 g/cm~3,比表面积为217m~2/g:碳元素以SiCO_3和自由碳的形式存在,Si-C-O气凝胶的化学式为SiC_(0.15)O_(1.7)7+0.23C_(free),由纳米级颗粒相互连接向成;与SiO_2气凝胶相比,由于部分氧原子被碳原子取代形成Si-C键,Si-C-O气凝胶具有比SiO_2气凝胶更好的耐温性,1000℃下比表面积为208.6 m~2/g。
Nano porous porous Si-C-O aerogels were prepared by using tetraethyl orthosilicate and dimethylethoxysilane as starting materials and sol-gel, supercritical drying and pyrolysis at 1200 ℃. The chemical composition and structure of Si-C-O airgel were investigated by TG-DTA, SEM and NMR. The results showed that the airgel changed from white to black after pyrolysis at 1200 ℃: the density was 0.3 g / cm ~ 3 and the specific surface area was 217m ~ 2 / g: the carbon was in the form of SiCO_3 and free carbon, The chemical formula of the gel is SiC_ (0.15) O_ (1.7) 7 + 0.23C_ (free), which is formed by the interconnection of nanoscale particles. Compared with SiO_2 aerogels, part of the oxygen atoms are replaced by carbon atoms to form Si-C Key, Si-CO airgel has better temperature resistance than SiO 2 airgel, and the specific surface area is 208.6 m 2 / g at 1000 ℃.