关键词: Al₂O₃气凝胶, 隔热材料, 比表面积, 孔径分布

Abstract: To optimize the preparation of Al₂O₃ aerogels,the sol-gel method was combined with supercritical drying,using aluminum isopropoxide (AIP) as precursor,ethanol (EtOH) as solvent,and acetic acid (HAc) as catalyst. The effects of the ethanol addition [n(AIP)∶n(EtOH)∶n(H₂O)∶n(HAc)=1∶8∶0.8∶2,1∶12∶0.8∶2,1∶16∶0.8∶2,and 1∶20∶0.8∶2] and acetic acid addition [n(AIP)∶n(EtOH)∶n(H₂O)∶n(HAc)=1∶16∶0.8∶1,1∶16∶0.8∶2,1∶16∶0.8∶3,and 1∶16∶0.8∶4] on the pore structure and specific surface area of Al₂O₃ aerogels were studied. The results show that ethanol affects the pore structure of Al₂O₃ aerogels by affecting the condensation probability of Al—OH groups,and acetic acid affects the pore structure of Al₂O₃ aerogels by affecting the reaction rate; when n(AIP)∶n(EtOH)∶n(H₂O)∶n(HAc)=1∶16∶0.8∶2,the Al₂O₃ aerogel has a porous microstructure,and its internal pore diameter is generally smaller than the average free path of air molecules,showing excellent thermal insulation characteristics,low density of 0.20 g·cm^-3,and the specific surface area of 458,102,and 51 m²·g^-1 at 25,1 000,and 1 200 ℃,respectively.

Key words: alumina aerogel, thermal insulation material, specific surface area, pore size distribution