Preparation of Porous Alumina Ceramics by Using the Gelation of Ammonium Alginate

The gelation of ammonium alginate by hydrochloric acid was applied for the formation of gel-like precursor composed of alumina particles and alginic polymer. The porous alumina ceramics fired at temperatures from 1000° to 1600°C had very sharp pore size distributions. Their porosity ranged from 17 to 56%, which was 15 to 20% higher compared with that of porous alumina prepared by the slip casting method. Furthermore, the pore structure was more stable at high temperatures than that of the slip casting method. The optimum concentration of ammonium alginate for the uniform mixing of each raw material was 0.3 to 2.0wt%. The concentration of hydrochloric acid was over 0.1N for the sufficient gelation of the gel-like precursor.