Porous mullite ceramics obtaining by freeze-casting

This work aims to obtain porous mullite ceramics from the freeze-casting kaolin and alumina mixture using gelatin as an additive for pore morphological modification. To obtain the samples, aqueous dispersions with 40% by volume of solids were prepared using ammonium polyacrylate (C₃H₃NaO₂) and ammonium hydroxide (NH₄OH) as dispersants, and as additives 6% gelatin and 0.5 % or 1.0% surfactant as a foaming agent. Structural, morphological, physical and mechanical characterizations of the samples were performed. After evaluation of the results, the efficiency of the freeze-casting process was observed, obtaining mulitic ceramics with spherical pores, average porosity of 49.6% and compressive strength around 2.5 MPa. (author)