Hydroxyapatite Coating on Titanium by Thermal Decomposition

Abstract

Hydroxyapatite (HA) coatings on Ti implants are made by the physical methods, mainly plasma spraying. We have developed a new chemical coating technique, thermal decomposition method. This method consisted of applying HA or perovskite (CaTiO₃) coating solution containing organometals, phosphate ester (only in HA solution), and organic solvents onto the surface of Ti and then sintered it at 650°C. The process was repeated several times. The thin and homogeneous layer included an initial CaTiO₃ layer with a thickness of 0.6 μm followed by an HA layer (2.4 μm) on top. The underlying CaTiO₃ layer reduced oxidation of the Ti substrate and enhanced stability of the coating.