Coating of CaTiO3 on titanium substrates by hydrothermal reactions using calcium-ethylene diamine tetra acetic acid chelate.

Titanium plates were treated in [Ti(O2)EDTA]2- -Ca(EDTA)2- mixed solutions and/or Ca(EDTA)2- solutions (where EDTA is ethylene diamine tetra acetic acid) at pH 9-13 and 150-250 degrees C for 0.5-12 h. The film, about 50 microm thick, and consisting of mixtures of CaTiO3 and TiO2 was formed in 0.01 M [Ti(O2)EDTA]2- - 0.01 M Ca(EDTA)2- mixed solution at pH 13 and 250 degrees C for 6 h. The film consisted of large icosahedral and hexagonal particles, of about 10 microm diameter, and small aggregated particles, of about 1 microm diameter. On the other hand, the film, about 20 microm thick, consisted of hexagonal plate-like CaTiO3 particles, of about 1 microm diameter, was formed in 0.01 M Ca(EDTA)2- solution at pH 13 and 250 degrees C for 6 h. The thickness of both films increased with time, where the film formation rate in 0.01 M [Ti(O2)EDTA]2- - 0.01 M Ca(EDTA)2- mixed solution was much faster. The CaTiO3 film formed on the surface of titanium promoted the precipitation of hydroxyapatite on the substrate by the hydrothermal reactions in Ca(EDTA)2- -PO(4)3- mixed solutions.