Hydroxyapatite-silicon film deposited on Ti-Nb-10Zr by electrochemical and magnetron sputtering method

The purpose of this study was to investigate silicon-doped hydroxyapatite (HA) films deposited on Ti-35Nb-10Zr by an electrochemical and magnetron sputtering method. The Ti-35Nb-10Zr alloy was manufactured in an arc-melting furnace. Electrochemical deposition of HA was performed by pulsing the potential, using cyclic voltammetry, in the electrolyte composed of 5 mM·Ca(NO3)2·4H2O + 6.0 mM·NH4H2PO4 at 85 °C. The silicon doping was performed with a pure Si target by radio-frequency (RF) magnetron sputtering with variable deposition time. The surface characteristics were investigated by field-emission scanning electron microscopy, X-ray diffraction, and electrochemical corrosion testing. It was found that the Si particles on the electrochemically deposited HA layer became thicker with increased sputtering time. The composition of the Si-HA coating surface showed a decrease of the Ca/P ratio with increased sputtering time. The intensity of X-ray diffraction peaks for the HA coating was increased by annealing, and there were no phase changes or appearance of other peaks from the annealing treatment. From the corrosion test, an increase in Si sputtering time could cause higher corrosion potential and lower corrosion current density. Increasing the Si sputtering time increased the corrosion resistance in the passivation region.