Control of porosity and pore size for porous alumina prepared from α-alumina, BaSO4 and/or SrSO4

A novel fabrication method for porous alumina ceramics was introduced. Porous Ba beta-alumina and Sr beta-alumina were fabricated using alpha-alumina, BaSO4 and/or SrSO4 as starting materials. Two heating steps and a leaching process are applied to attain high porosity. The first heating was for sintering and transformation of alpha-alumina to beta-alumina, and the second was for melting of sulfate and evaporation of SOx. Porosity reached about 55% and 75% for 40 vol% and 50 vol% sulfate added samples regardless of sulfate species. Mean diameter increased with the increase of the porosity for BaSO4 SrSO4, and (BaSO4 + SrSO4) systems. Pore size distribution of all the samples displayed relatively sharp mono-peak mode. Maximum pore size of all systems were smaller than those of raw sulfates.