Wu Yu, Wang Xiaodong, Liu Lin, Zhang Ze, Shen Jun
Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China.
Gels. 2021 Aug 14;7(3):122. doi: 10.3390/gels7030122.
In this study, we used two methods to prepare alumina-doped silica aerogels with the aim of increasing the thermal stability of silica aerogels. The first method was physical doping of α-AlO nano powders, and the second method was to create a chemical compound via the co-precursor of TEOS and AlCl·6HO in different proportions. The shrinkage, chemical composition, and specific surface area (SSA) of samples after heating at different temperatures were analyzed. Our results show that the silicon hydroxyl groups of samples derived from AlCl·6HO gradually decreased and nearly disappeared after heating at 800 °C, which indicates the complete dehydration of the silicon hydroxyl. Thus, the samples exhibited a large linear shrinkage and decreased SSA after high-temperature heat treatment. By contrast, samples doped with α-AlO powders retained abundant silicon hydroxyl groups, and the 6.1 wt.% α-AlO-doped sample exhibited the lowest linear shrinkage of 11% and the highest SSA of 1056 m/g after heat treatment at 800 °C. The alumina-doped silica aerogels prepared using a simple and low-price synthesized method pave the way for the low-cost and large-scale production of high-temperature thermal insulation.
在本研究中，我们使用两种方法制备氧化铝掺杂的二氧化硅气凝胶，目的是提高二氧化硅气凝胶的热稳定性。第一种方法是对α-AlO纳米粉末进行物理掺杂，第二种方法是通过不同比例的正硅酸乙酯（TEOS）和六水合氯化铝（AlCl·6HO）的共前驱体形成一种化合物。分析了在不同温度下加热后样品的收缩率、化学成分和比表面积（SSA）。我们的结果表明，源自AlCl·6HO的样品中的硅羟基在800℃加热后逐渐减少并几乎消失，这表明硅羟基完全脱水。因此，样品在高温热处理后表现出较大的线性收缩率和降低的比表面积。相比之下，掺杂α-AlO粉末的样品保留了丰富的硅羟基，并且在800℃热处理后，6.1 wt.%α-AlO掺杂的样品表现出最低的线性收缩率11%和最高的比表面积1056 m/g。采用简单且低成本的合成方法制备的氧化铝掺杂二氧化硅气凝胶为低成本大规模生产高温隔热材料铺平了道路。
