Use of Wet Chemical Method to Prepare β Tri-Calcium Phosphates having Macro- and Nano-crystallites for Artificial Bone

Abstract

Calcium phosphate crystallites were prepared by wet chemical method for use in artificial bone. In order to obtain β-tricalcium phosphate (TCP), nano-crystalline calcium phosphate (CaP) was precipitated at 37℃ and at pH5.0±0.1 under stirring using highly active Ca(OH)₂ in DI water and an aqueous solution of H3PO4. The precipitated nano-crystalline CaP solution was kept at 90℃ for the growth of CaP crystallites. Through the growing process of CaP crystallites, we were able to obtain various sizes of rectangular CaP crystallites according to the crystal growing times. Dry nano-crystalline CaP powders at 37℃ were mixed with dry macro-crystalline CaP crystallites and the shaped mixture sample was fired at 1150℃ to make a β-TCP block. Several tens of nm powders were uniformly coated on the surface, which was comprised of powders of several tens of μm, using a vibrator. The mixing ratio between the nanometer powders and the micrometer powders greatly affected the mechanical strength of the mixture block; the most appropriate ratio of these two materials was 50 wt% to 50 wt%. The sintered block showed improved mechanical strength, which was caused by the solid state interaction between the nano-crystalline β-TCP and the macro-crystalline β-TCP.