Hydroxyapatite precipitation on nanotube surfaces of Ti-35Ta-xNb alloys

Hydroxyapatite precipitation on nanotube surfaces of Ti-35Ta-xNb alloys was investigated using electrochemical methods. The alloys were prepared by arc-melting, heat treated at 1050 degrees C for 12 h in an Ar atmosphere, and quenched in 0 degrees C water. Nanotubes were created on the Ti-35Ta-xNb alloys in a 1 M H3PO4 + 1.2 wt.% NaF electrolyte at room temperature. Hydroxyapatite precipitation was carried out in a 0.03 M Ca(NO3)2 x 4H2O + 0.018 M NH4H2PO4 solution at 80 ± 1 degrees C, using 10 deposition cycles. Information about morphology and composition was obtained by FE-SEM and EDS. The microstructure of the Ti-35Ta-xNb alloys was transformed from α phase to βphase as the Nb content increased. The HA precipitates had a plate-like morphology on bulk Ti-35Ta-xNb alloys and a flower-like morphology on nanotubular Ti-35Ta-xNb alloys.