Highly thermally stable alumina-based aerogels modified by partially hydrolyzed aluminum tri-sec-butoxide
Highly thermally stable alumina-based aerogels modified by partially hydrolyzed aluminum tri-sec-butoxide
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DOI：
10.1007/s10971-017-4380-5
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发表时间：
2017-04
影响因子：
2.5
通讯作者：
Wenbing Zou;Xiaodong Wang;Yu Wu;Guoqing Zu;Liping Zou;Rongyan Zhang;Xiandong Yao;Jun Shen
中科院分区：
文献类型：
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作者：
Wenbing Zou;Xiaodong Wang;Yu Wu;Guoqing Zu;Liping Zou;Rongyan Zhang;Xiandong Yao;Jun Shen
摘要采用丙酮-苯胺原位水形成法合成了高热稳定的氧化铝基气凝胶，并在不同温度（25、45和60 °C）下用部分水解的三仲丁醇铝对其进行了改性。研究了改性温度对氧化铝基气凝胶微观结构和热稳定性的影响。改性后，氧化铝基气凝胶的形貌由针状颗粒相互连接的网状结构转变为片状颗粒相互堆叠的片状结构，从而提高了耐热性。氧化铝基气凝胶的热稳定性随着改性温度的升高而增强，但高温（60 °C以上）会导致湿凝胶在改性过程中由于高溶解度而溶解。在1200 °C下退火2 h后，45 ° C改性的氧化铝基气凝胶表现出最佳的热稳定性，具有最低的线性收缩率约7%和最高的比表面积154 m2/g。另外，改性后的气凝胶在1300 °C退火后仍保持θ-Al 2 O3相，而未改性的气凝胶转变为α-Al 2 O3相。通过引入莫来石纤维毡和TiO 2，氧化铝基气凝胶得到进一步增强。所获得的复合材料在800、1000和1200 °C下分别显示出0.065、0.086和0.118 W/mK的超低热导率。
AbstractHighly thermally stable alumina-based aerogels are synthesized by the acetone–aniline in situ water formation method and modified by partially hydrolyzed aluminum tri-sec-butoxide at different temperatures (25, 45, and 60 °C). The effects of modification, especially modification temperature, on microstructure and thermal stability of alumina-based aerogels are investigated. After the modification, the morphologies of alumina-based aerogels change from the network structures with interconnected needle-like particles to those with stacked sheet-like particles, resulting in a better heat resistance. The thermal stability of alumina-based aerogels enhances with the increasing modification temperature, whereas the high temperature (more than 60 °C) would lead to the dissolution of wet gels during the modification process due to the high solubility. After annealing at 1200 °C for 2 h, the 45 °C-modified alumina-based aerogel exhibits the best thermal stability with the lowest linear shrinkage of ~7% and the highest specific surface area of 154 m2/g. In addition, the modified aerogels remain in theθ-Al2O3phase while the unmodified one transforms intoα-Al2O3phase after 1300 °C annealing. The alumina-based aerogels are further reinforced by incorporating with mullite fiber felt and TiO2. The obtained composites show ultralow thermal conductivities of 0.065, 0.086, and 0.118 W/mK at 800, 1000, and 1200 °C, respectively.Graphical Abstract