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Coating of Hydroxyapatite on Titanium Plates Using Thermal Dissociation of Calcium-EDTA Chelate Complex in Phosphate Solutions under Hydrothermal Conditions

1995; Elsevier BV; Volume: 173; Issue: 1 Linguagem: Inglês

10.1006/jcis.1995.1304

1095-7103

Yoshinobu Fujishiro, Akitoshi Fujimoto, Tsugio Sato, Akitsugu Okuwaki,

Marine Biology and Environmental Chemistry

Hydroxyapatite films were formed on the surfaces of titanium plates by the homogeneous precipitation technique using hydrothermal reactions in Ca(edta)2--NaH2PO4 solution at 120-200°C and pH 4.0-10.0 for 2-20 h. When titanium plates were directly treated in 0.05 M Ca(edta)2--0.05 M NaH2PO4 solutions at 160°C for 2 h, they were uniformly coated with the films that consisted of mixtures of large plate-like monetite particles and fine needle-like hydroxyapatite particles at pH 5, whereas aggregates consisting of needle-like and/or rod-like hydroxyapatite and plate-like monetite were deposited on the surface as islands above pH 6 and at pH 4, respectively. The plate-like monetite formed in the initial stage of the reaction at pH 5.0 was converted to needle-like hydroxyapatite with time due to increasing solution pH above 5.5. Double-coating, in which titanium plates were successively treated in 0.05 M Ca(edta)2--0.05 M NaH2PO4 solution at pH 5.5 and 160°C for 2 h, to coat the surface entirely with a thin film consisting of monetite and hydroxyapatite, and in 0.05 M Ca(edta)2- -0.05 M NaH2PO4 solution at pH 6-9 and 160°C, was useful to promote the formation of hydroxyapatite coating.