Effect of Drying Method on the Physicochemical and Structural Properties of Alumina Alcogel Produced by Sol-Gel Method

Because of its superior thermal and mechanical properties, alcogels, which are mainly used in space technology, are known as super insulation and environment friendly materials with low density and high porosity. Generally, they are produced in three stages using sol-gel technique known as hydrolysis and condensation of inorganic salts or metal alkoxides. The final stage is the drying of the wet gel, and it is of great importance to select the most suitable drying technique to protect the porosity and structure of wet gel. In this study, the physicochemical and structural properties of porous materials obtained by using sol-gel technique under three different drying conditions which are supercritical conditions, atmospheric pressure and freezing, were characterized by XRD, TGA/DSC, FT-IR and BET analyzes. Taking into account the physicochemical properties and thermal behavior of these gels, which have amorphous structure and named aerogel, cryogel and ambigel in different drying conditions, it is concluded that the best drying technique for drying wet gels is freeze drying without pretreatment.