Surface characteristics of HA coated Ti-30Ta-xZr and Ti-30Nb-xZr alloys after nanotube formation

In this study, surface characteristics of hydroxyapatite(HA) coated Ti-30Ta-xZr and Ti-30Nb-xZr alloys after nanotube formation have been investigated by EB-PVD, FE-SEM, XRD and potentiostat. The microstructures of the Ti-30Ta-xZr alloy had a needle-like morphology, and the thickness of this needle-like structure increased as the Zr content increased. The microstructures of the Ti-30Nb-xZr alloy had an equiaxed grain structure. The nanotubes were mainly nucleated and grown at β phase in case of Ti-30Ta-3Zr, but nanotubes were nucleated at α phase in case of Ti-30Ta-15Zr alloy. The corrosion resistance of alloy increased as Zr content increased, and nanotubular surface with highly ordered small and large tubes was high corrosion resistant. The corrosion resistance of HA coated alloys after nanotube formation was higher than that of the non-HA coated nanotubular alloy.