采用溶胶-凝胶法和CO2超临界干燥工艺制备RF/Al2O3复合气凝胶,再经高温热处理过程得到轻质高强度C/Al2O3复合气凝胶,研究了不同热处理温度对气凝胶结构的影响,利用氮气吸附、X射线衍射、扫描电子显微镜和透射电子显微镜等手段对气凝胶的结构和性能进行了分析并且测试了不同热处理温度样品的压缩强度。实验结果表明:C/Al2O3复合气凝胶具有均匀的三维网络结构且成块性好,随着热处理温度的升高,气凝胶比表面积和强度均先增大后减小,当1400℃时,C/Al2O3复合气凝胶比表面积最高,为831m2·g^-1,压缩强度最大,为9.5MPa。
Resorcinol-formaldehyde/alumina composite (RF/Al2O3) aerogels were prepared using sol-gel techniques and supercritical fluid CO2 drying. RF/Al2O3 aerogels were successfully converted to light and high- strength carbon/alumina composite (C/Al2O3) aerogels after high temperature thermal treatment process. The effects of different thermal treatment temperature on the aerogels structures were studied. The structures and properties of aerogels were analyzed by means of BET, XRD, SEM, TEM and the compressive strengths were also measured. The experimental results showed that the as-synthesized C/Al2O3 aerogels with great monolithic morphology exhibited a three-dimensional network structure. With the increasing of thermal treatment temperature, both specific surface area and compressive strength of aerogels were first increase and then decrease. In particular, the C/Al2O3 aerogels treated by the thermal treatment temperature of 1 400 ℃ had the highest specific surface area and compressive strength (831 m2·g^-1 and 9.5 MPa, respectively).