Preparation of highly concentrated aqueous hydroxyapatite suspensions for slip casting

This paper reports the preparation of highly concentrated aqueous hydroxyapatite (HA) suspensions for slip casting of dense bone implants. The dispersing behaviour of HA powders in aqueous media was monitored by viscosity and zeta potential analyses as a function of pH of the slurry. The rheological properties of concentrated aqueous hydroxyapatite suspensions have been characterized with varying pH, NH4PAA concentration and solids loading. The intrinsic pH of the suspension was found suitable for slip casting. The optimum dispersant concentration is 0.75 wt.% for 75 wt.% solid loading. A stable suspension with 75 wt.% solid was suitable for slip casting with viscosity of 0.36 Pa s at 100 s−1. Finally, crack-free and dense microstructures have been obtained successfully with a grain size of 2–5 μm.