关键词: 氧化铝气凝胶, 耐高温, 隔热材料, 比表面积

Abstract: This work aims to investigate the high-temperature resistance and the thermal insulation of alumina aerogels at high temperatures.Alumina aerogels were prepared by the sol-gel method plus supercritical 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 treatment 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 ℃.

Key words: alumina aerogel, high temperature resistance, insulation material, specific surface area