Freeze gelcasting of naphthalene-in-aqueous alumina slurry emulsions prepared from slurries of various alumina concentrations were studied to prepare macroporous alumina ceramics of high porosity. The compressive strength and Young's modulus of the gelled emulsion bodies increased with an increase in naphthalene to alumina slurry volume ratio and a decrease in the alumina slurry concentration. Macroporous alumina ceramics obtained were characterized for their microstructure, porosity, pore size and compressive strength as a function of naphthalene to alumina slurry volume ratio and alumina concentration in the aqueous slurry. Porosity (65 to 90 vol.%) increased with an increase in naphthalene to alumina slurry volume ratio and a decrease in alumina slurry concentration. The compressive strength and Young's modulus of the macroporous alumina ceramics were fitted with the model equations proposed by Gibson and Ashby. The gelled emulsions showed paste-like consistency which enabled easy fabrication of macroporous alumina tiles by compression moulding.

Keywords: Emulsion, Shaping, Freeze gelcasting, Porosity, Al2O3, Strength.