1999 Volume 18 Issue 3 Pages 259-270
Calcium phosphates were formed on five kinds of substrate metals using a hydrothermal-electrochemical method in an autoclave with two electrodes. The electrolyte dissolving NaCl, K2HPO4, CaCl2⋅2H2O, tris (hydroxymethyl) aminomethane, and hydrochloric acid was maintained at 100°C, 150°C and 200°C. The counter electrode, the anode, was platinum plate, 20×20×0.5mm, and the working electrodes as cathode were pure titanium, pure zinc, pure nickel, pure iron, and stainless steel plates. A constant direct current at 12.5mA/cm2 was loaded for 1hr. Hydroxyapatite [Ca10(PO4)6(OH)2] only deposited at three temperatures on pure titanium plate. On pure zinc plate, both parascholzite [CaZn2(PO4)2⋅2H2O] and hydroxyapatite were formed at 150°C and both parascholzite and ZnO were formed at 200°C. Both hydroxyapatite and β-TCP [β-Ca3(PO4)2] were formed on pure nickel, pure iron, and stainless steel plates at 200°C. It seems that the incorporation of the metal ions released from the electrode decreased the Ca/P ratio of the deposit due to the formation of other compounds except hydroxyapatite.