Abstract: The electrophoretic and rheological properties of nano-zirconia slurries containing high concentrations of the electrolytes (NaCl, NH₄Cl,
(NH₄)₂CO₃) were studied. It was indicated that zeta potential of zirconia slurries decreases when increasing the concentration of the electrolytes,
but the isoelectric point (IEP) of the slurries is basically invariable. The IEP of zirconia slurries is different while in different species of
electrolytes. An attractive, connective particle network is present with the addition of salt ions and induces to the thixotropy of the slurry. High solid
content slurries are more sensitive to the salt ions expressed in the decreasing of critical coagulationconcentration. Hence, the existence of electrolytes is disadvantageous to the preparation of high solid content slurries but can
promote coagulation of the slurries.

Key words: zirconia slurry, salt ion, rheological properties, coagulation