SYNOPSIS This study is concerned with the fabrication of engineering ceramics parts with complicated shape by using slip casting process. Preparation conditions of slurries for 3 kinds yttria partially stabilized zirconia (Y-PSZ) powders were examined by the measurement of zeta-potential and viscosity. As the powder characteristics, the isoelectric points of Y-PSZ powders were determined from zeta-potential measurement to be pH7.9 and 9.0 for powders produced by hydrolysis and pH5.3 for a

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... produced by neutralization coprecipitation. Welldispersed slurries were found for Y-PSZ powders by adding organic polymer deflocculant (polycarboxilic ammonium) to the zeta-potential of the powder becoming enough high at the negative side. When the adding amount of deflocculant was shorted and the zeta-potential was around OmV, the viscosity of the slurry becoming very high and can't use for slip casting. In a case of a Y-PSZ powder produced by hydrolysis, low viscosity slurry can be prepared without adding deflocculant since the zeta-potential is high enough at the positive side.