热处理对块状氧化铝气凝胶微观结构的影响

宇航材料工艺 , 2010, 40(2): 51-54. doi: 10.3969/j.issn.1007-2330.2010.02.014

热处理对块状氧化铝气凝胶微观结构的影响

周洁洁 ^1, , 陈晓红 ^2, , 胡子君 ^3, , 孙陈诚 ^4, , 陈海坤 ^5, , 宋怀河 ^6,

1.北京化工大学化工资源有效利用国家重点实验室,北京,100029

2.北京化工大学化工资源有效利用国家重点实验室,北京,100029

3.航天材料及工艺研究所先进功能复合材料技术国防科技重点实验室,北京,100076

4.航天材料及工艺研究所先进功能复合材料技术国防科技重点实验室,北京,100076

5.航天材料及工艺研究所先进功能复合材料技术国防科技重点实验室,北京,100076

6.北京化工大学化工资源有效利用国家重点实验室,北京,100029

基金项目: 先进功能复合材料技术国防科技重点实验室基金资助(9140C5601040802)

关键词：块状 , 氧化铝气凝胶 , 比表面积 , 热处理

Effect of Heat Treatment on Microstructure of Monolithic Alumina Aerogels

Keywords： Monolithic , Alumina aerogel , Surface area , Heat treatmen

以AlCl_3·6H_2O为前驱体,无水乙醇和去离子水的混合溶液为溶剂,环氧丙烷为凝胶网络诱导荆,通过溶胶-凝胶技术制备得到溶胶,再经超临界干燥制备出块状氧化铝气凝胶.采用SEM、TEM、XRD、BET等手段,对氧化铝气凝胶在不同热处理温度下的微观结构进行了对比和分析.结果表明,氧化铝气凝胶的主要成分为多晶勃姆石相,微观结构由许多叶片状纤维堆积形成,经500和1 000℃热处理后成块性未受到明显的影响,比表面积各为429和174 m~2/g.在20～1000℃内,氧化铝气凝胶发生了由多晶态勃姆石相→γ-Al_2O_3→δ-Al_2O_3的相转变.

Alumina aerogels were prepared through addition of propylene oxide to aqueous or ethanolic solutions of hydrated aluminum salts AlCl_3·6H_2O, followed by drying with supercritical ethanol. Microstructure of alumina aerogels were contrasted and analyzed at different temperatur by means of transmission electron microscopy, powder X -ray diffraction and nitrogen adsorption/desorption analysis. The results show that the aerogel microstructures contain highly reticulated networks of boehmite fibers, no significant loss in monolithicity occurred during heat treatment of alumina aerogels at 500℃ and 1 000℃, the surface area is 429 m~2/g and 174 m~2/g. The phase conversion in the range from 20 to 1 000℃ are as follows: boehmite→γ-Al_2O_3→δ-Al_2O_3.

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