Dispersion of aqueous alumina suspensions using copolymers with synergistic functional groups

A copolymer containing carboxylic acid, carboxylate ester, sulfonic acid, and phosphonic acid groups was used as a dispersant to prepare aqueous alumina suspensions. The adsorption and desorption behavior of the dispersant were characterized using potentiometric titration and Auger electron spectroscopy (AES) method, respectively. The influence of the copolymer on the electrokinetic properties of Al2O3 was studied. The rheological behavior of the alumina suspension was measured as a function of pH, copolymer dosage and solid volume fraction. The optimum copolymer concentration was found to be 0.2 wt.%, which was independent of the solid content. Compared with ammonium polyacrylate (NH4PAA), this copolymer can effectively reduce the viscosity of alumina suspensions over a wider pH range. A concentrated slurry having a volume content of 58 vol.% was prepared at pH 9.5 using this copolymer and was consolidated by gel casting. The microstructure of the green and sintered bodies was characterized by using scanning electron microscopy (SEM).