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SiO2aerogel is a kind of nano light porous materials with high specific surfacearea, low density, low thermal conductivity and low velocity. As the important methodfor SiO2aerogel, ambient drying often cracks and break during drying withunsatisfactory property. The paper researched how to avoid pore collapse and gelcracks by the research on two-step sol-gel and gel aging. The objective is obtaining akind of SiO2aerogel with low density and low thermal conductivity.The effect of ammonia concentration, hydrolysis time, sol pH value on the geltime, aerogel density have been studied within sol-gel. The result shows that, sol pHvalue on the gel time has great influence on SiO2aerogel, in sol-gel process, theprocess of sol-gel was at last confirmed as: adjusting pH value to12, standing for24h, adjusting pH value to56. Compared with one-step, two-step sol-gel make thepore more tinier, the constitution more loser, the density decreased55.1%, theconductivity decreased28.3%. The effect of aging time, exchanging time of solvent,the arrangement of aging procedure and the proportion of flux have been studiedwithin gel aging procedure. The result shows that, a different arrangement of agingprocedure has great influence on SiO2aerogel. The process of gel aging procedurewas at last confirmed as: aging48h-exchanging solvent24h-aging48h-exchangingsolvent48h-surface modification12h, the proportion of flux isV（TEOS）:V（EtOH）=2:8.FT-IR, XRD, SEM and BET surface area have been studied to characterize phase,specific surface area, partical size, morphology and hydrophobic, heat insulationperformance of SiO2aerogel. The result shows that: SiO2aerogel was a kind ofamorphous material with desenty0.0903g/cm3, porosity95.9%, pore size9.35nm,partical size9.39nm, specific surface area635m2/g, thermal conductivity0.02103W/（m·k）. It appears white with bluish fluorescence and translucent; themicro-morphology shows that the SiO2aerogel was composited by nanometer-gradegrain with a loose structure which was homogeneous diameter, and the FT-IR shows that there was-CH3in surface, contact angle125°and well hydrophobicity. Besides,the thermal conductivity decrease with the density decrease.
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