Tape casting of zirconia for ion conducting membranes. A study of dispersants

Powders of fully yttria stabilized zirconium oxide have been studied in order to identify efficient dispersants for zirconia in tape casting slurries, and to verify that they do not impair the oxygen ion conductivity of the final membrane. Of eleven screened dispersants, only three were shown to be efficient. Sintered plates prepared with these dispersants had high and about equal oxygen ion conductivity (0.16–0.19 S cm⁻¹ at 1000°C). The use of a phosphate ester as dispersant, possibly leaving traces of phosphorus in the sintered plate, did not impair the oxygen ion conductivity. Fish oils, common dispersants for tape casting slurries, were not efficient for zirconia in the solvent system that was studied. The addition of binder and plasticizers to the dispersions to form tape casting slurries did not cause reagglomeration.