Preparation of calcium phosphate coating on pure titanium substrate by electrodeposition method

Abstract

The influences of pH value, electrolyte temperature and loading time on depositing calcium phosphate coating on pure titanium substrate by electrodeposition process were investigated. The process was carried out with an electrochemical work-station supplying a direct current power at potential of −0.8V (vs SCE). The electrolyte consists of 7 mmol · L⁻¹ CaCl₂ · 2H₂O, 3 mmol · L⁻¹ Ca(H₂PO₄)₂ · H₂O and 2.5% H₂O₂. NaOH and HCl solutions were used to adjust pH value. The deposited samples were characterized by X-ray diffraction and scanning electron microscope. The comparison of the deposits obtained at lower and higher pH values demonstrates that the crystallization process at the interface is favoured by high pH value. With temperature increasing, the deposited hydroxyapatite is occasionally of plate-like shape, and the width and the length of the deposited calcium phosphates at 65 °C are larger than those at 55 °C. Therefore, it is confirmed that the morphology and microstructure of electrochemically deposited calcium phosphates can be regulated. Additionally, the coating formed in electrolyte with H₂O₂ additive is homogeneous and the evolution of H₂ bubble can be eliminated.

Keywords

calcium phosphate / coating / electrodeposition / XRD / SEM