Rheological behavior of organic suspensions of fluorapatite

A fluorapatite suspension prepared in the azeotrope methyl ethyl ketone-ethyl alcohol (MEK:EtOH) in the presence of the phosphoric ester was investigated. Electrical conductivity, adsorption isotherms, and sedimentation technique showed that the amount of phosphoric ester adsorbed on the fluorapatite surface was equal to, or higher than, 1 wt%. This dispersant concentration led to a good particle packing. The rheological properties of fluorapatite suspensions were studied as a function of phosphoric ester concentration. The data obtained from the viscosity measurements and those previously collected correlated well. In the case of suspensions prepared with 60 wt% in fluorapatite, the dispersion was optimal for a phosphoric ester content of about 1.3 wt%.