Rheological behaviour of aqueous suspensions of fluorapatite

M. P. ALBANO; L. B. GARRIDO

Foz de Iguazu

Congreso; 54 Congresso Brasileiro de Cerámica; 2010

Asociación Brasileira de Cerámica

A fluorapatite with a Ca/P atomic ratio of 1.67 close to the theoretical one could be obtained by milling the calcined mixture (Ca3(PO4)2: CaF2: 3:1) in an aqueous media with the pH initially adjusted at 9. The influence of NH4PA addition on the rheological propertied of 40 vol. % FA slips was studied. In addition, the influence of the volume fraction of solids on the rheological behaviour of stabilized FA slips was determined. Finally, the effect of Poly(vinyl)alcohol (PVA) addition on the relative viscosity of 38 vol. % FA suspensions stabilized with NH4PA was investigated. The minimum viscosity of 40 vol.% slips at pH 8.9 occurred at 0.6 wt% of NH4PA added. An important increase in the yield stress was pbserved for suspensions with a volume fraction of solids higher than about 46 vol.%. The addition of 0.5-1 wt% PVA to a well-stabilized FA slip caused aggregation of particles by a depletion flocculation mechanism, thereby increasing the slip viscosity.