HYDROXYAPATITE SYNTHESIZED BY A SIMPLIFIED HYDROTHERMAL METHOD

A simplified hydrothermal method of synthesizing hydroxyapatite powder is described. Heating powders of Ca(OH)(2), Ca(H2PO4)(2) . H2O and di stilled water in a pressurized pot at 109 degrees C for 1-3 h results in powders consisting of crystallized hydroxyapatite in a needle shape , 130-170 nm in length and 15-25 nm in width. The specific surface are a is 31-43 m(2)/g and the Ca/P ratio is 1.640-1.643. The obtained HA p owder can be sintered to a high density at 1200-1300 degrees C. No dec omposition was identified by X-ray diffraction. The optimally sintered ceramic has a pore-free surface structure with a flexural strength of 120 MPa, a micro-Vickers hardness of 5.1 GPa and fracture toughness o f 1.2 MPa . m(1/2). The biocompatibility of the pulverized sintered-ce ramic is excellent and comparable to that of a commercial grade hydrox yapatite by evaluating the implantation in a dog. The synthesis method is simple, economic, and results in a high quality powder which is us eful in hard tissue reconstruction applications. (C) 1996 Elsevier Sci ence Limited and Techna S.r.l.