Abstract
The development of porosity in sol-gel derived alumina is dependent on the phase transformations, chemistry, and other characteristics of the alumina precursor. The transformations of the aluminum hydroxides are particularly useful for designing a porous alumina with specific pore size, shape, distribution, and surface area. Dehydration results in the formation of transition aluminas with surface areas of several hundred m2/g and a distribution of intracrystalline micropores and intercrystalline mesopores. Coarsening of the transition alumina crystals and the topotactic transformations between transition aluminas lead to pore coarsening and a loss of surface area with further heating. The reconstructive transformation to α-Al2O3 replaces the micropores and mesopores of the transition aluminas with a distribution of interconnected macropores, resulting in surface areas of a few m2/g. The development and thermal stability of porosity is influenced by the precursor processing conditions, additives, and the calcination environment. Understanding and controlling the factors that influence the porosity and surface area is critical to the preparation and use of porous alumina.
Original language | English (US) |
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Pages (from-to) | 45-64 |
Number of pages | 20 |
Journal | Key Engineering Materials |
Volume | 115 |
State | Published - 1996 |
All Science Journal Classification (ASJC) codes
- General Materials Science
- Mechanics of Materials
- Mechanical Engineering