Sintered alumina samples were prepared by sol-gel method with three types of boehmite powders as starting materials. All dried gels were completely transformed to corundum phase at temperature above 1200 oC. Sintering characteristics of the dried gels were investigated according to heat treatment temperature. Relative densities of these gels dried at 1000 oC, 1200 oC and 1400 oC were 40%, 65% and 75% respectively, indicating incomplete densification. Specific surface areas of the dried gels heated at temperature up to 1000 oC depended on crystal grain sizes of boehmite powder used. However, specific surface areas of samples heated at 1200 oC were almost the same (range, 7.4 ~ 8.3 m2/g). Overall pore volume decreased with increasing sintering temperature. However, macropore gradually expanded due to sintering shrinkage of crystal grains, reaching a maximum at 1400 oC. Sintered body had a vermicular porous structure at sintering temperature up to 1300 oC. However, sintered body at sintering temperature of 1400 oC contained a relatively large amount of closed pores.

Keywords: Sol-gel method, Boehmite, Alumina gel, Microstructure, Sintering.