The Size Control of Hydroxyapatite Particles during Spray Pyrolysis

Abstract

The size of hydroxyapatite particles during spray pyrolysis was successfully controlled by varying the concentrations of the starting calcium phosphate (CaP) solutions. Three different concentrations of CaP solutions were prepared by dissolving Ca (NO3)2·4H2O and (NH4)2HPO4 into deionized water and then they were sprayed at 900°C with the carrier gas flowing rate of 10 L/min. The size of the resultant hydroxyapatite particles decreased as lowering the concentration of the starting CaP solution. The smaller the particle size, the higher the relative density of the hydroxyapatite disks after sintering at 1100°C for 1 hour. The practical implication of the results is that highly sinterable hydroxyapatite particles can be synthesized during spray pyrolysis by controlling the starting concentration of CaP solution.