Rheological characterization and coagulation casting of Al2O3–nano zirconia suspensions

The rheological behavior of electrosterically dispersed aqueous suspensions composed of submicron alumina and nano zirconia particles in different ratios and solids contents has been studied during in-situ coagulation casting. Glucono-δ-lactone was used as the coagulant to achieve destabilization of the ceramic suspensions by acidifying the suspension so that the pH became close to the isoelectric point (IEP) for both powders. The effect of the lactone content and the solids loading were studied on the rheological parameters during the coagulation process and the conditions optimized to yield homogeneous green samples with a uniform nano zirconia distribution and densities between 58 and 60% of theoretical. These were subsequently sintered to yield composites with a final density of 97%.