Preparation of hydroxyapatite powder by a spray dry method

Abstract

Hydroxyapatite (HA) powder was prepared by solid-state reaction method. HA powder was divided
into two parts. The first is used as a control and the second was calcined at 900oC for 1h used for spray drying.
As-prepared HA and calcined HA powders were characterized by XRD and SEM. The ratios of HA powder to
water content were varied then spray dried at 150oC and 200oC to investigate the morphology. Spray dried
powders were compacted under uniaxial a stress of 2 MPa and sintered at 1250oC for 2h. The density of
sintered compacts was determined using Archimedes’s technique. The flexural strength of sintered specimens
was measured in a three-point bending using a universal testing machine. From the results, spherical HA
granules of 2-35 μm were obtained by spray drying the calcined HA. The morphology of spray dried granules
varied with the concentration of slurries. Solid spheres and doughnut shapes were produced at slurry
concentrations of 15-20%HA and 30%HA, respectively. The physical and mechanical properties of HA
ceramics were improved by spray drying technique. The maximum density and fracture strength of spray dried
calcined HA of 90.90 % theoretical and 117 MPa could be obtained from 30%HA spray dried at 200oC.