Hydroxyapatite coating on micropore-formed titanium alloy utilizing electrochemical deposition

• Hydroxyapatite layers were deposited on anodized CP Ti by an electrochemical method.
• Flake-like and needle-like CaP crystals were observed at deposition temperatures of 25 °C and 85 °C, respectively.
• The morphology of the CaP crystals in these layers was strongly affected by the electrolyte temperature.

The purpose of this study was to investigate hydroxyapatite coatings on micropore-formed titanium alloy, utilizing an electrochemical deposition method. A commercially pure titanium surface was used as a substrate for calcium phosphate (CaP) deposition on micropores formed after anodization. Prepared surfaces were anodized in 1 M H3PO4 solution, and CaP deposition was performed with a potentiostat at cathodic potential in an electrolyte containing 0.042 M Ca(NO3)2 and 0.025 M NH4H2PO4. Micropores acted as growth sites for nanophase CaP crystals. Flake-like CaP and needle-like CaP were observed at 25 °C and 85 °C, respectively. If the specimen was not heat-treated, octacalcium phosphate and hydroxyapatite were observed, whereas slight CaP decomposition to tricalcium phosphate occurred with heat treatment at 700 °C. The phenomena involved in CaP deposition were affected by the electrolyte temperature for both morphology and nucleation site.