Influence of powder characteristics on the rheological behaviour of hydroxyapatite slurries

A study of the influence of several dispersants (nature a nd concentration), of the calcination temperature and of the concentration of hydroxyapatite (HAP), on the rheological behaviour of HAP slurries, made it possible to obtain low viscosity slurries containing 73 wt% HAP and 3.5 wt% dispersant. The calcination of the HAP powder affected both the morphology and the chemical nature of the surface of particles. This last effect was clearly shown by the decrease of the zeta potential with increasing calcination temperature. The optimal calcination temperature was chosen beyond 800 degrees C. Parts sintered at 1 200 degrees C for 30 min were obtained with a density higher than 96% of theoretical by casting optimized suspensions.