This work aims to investigate the high-temperature resistance and the thermal insulation of alumi-na aerogels at high temperatures.Alumina aerogels were prepared by the sol-gel method plus supercriti-cal drying using aluminum isopropoxide as the precursor,ethanol as the solvent,and glacial acetic acid as the catalyst.The obtained alumina aerogels were then heat-treated at different temperatures(25,150,250,300,500,600,850,1 000 and 1 200 ℃)for 6 h.The effects of the heat treatment temperature on the phase composition,microstructure,pore structure and specific surface area of the alumina aerogels were studied by FT-IR,XRD,TGA,DSC,SEM,TEM and BET.The results show that:(1)with the increasing heat treat-ment temperature,the prepared alumina aerogels undergo phase transition;when the temperature is 600 ℃,the sample mass hardly changes;(2)when the temperature is 850 ℃,the prepared alumina aerogel still maintains a three-dimensional porous network skeleton structure,the average pore size is still less than 69 nm(the free path of air molecules),and there is no obvious macropore;(3)the specific surface area of the prepared alumina aerogel is 458 m2·g-1 at room temperature,321 m2·g-1 after heat treatment at 850 ℃,and 102 m2·g-1 after heat treatment at 1 000 ℃.
alumina aerogelhigh temperature resistanceinsulation materialspecific surface area
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