The Morphostructural, Compositional, and Electrochemical Characterization of Electrodeposited Nanolayers on a New Ti-15Ta-5Zr Alloy

A porous, homogeneous, phosphorous-enriched oxide nanolayer was realized on the new Ti-15Ta-5Zr alloy surface by the anodic galvanostatic electrodeposition in phosphoric acid solution. This nanolayer contains TiO2, ZrO2 oxides, tantalum suboxides, and PO 4 3 - ions incorporated in the time of the electrodeposition process and has a thickness of 15.5 nm (X-ray photoelectron spectroscopy data). Atomic force microscopy determined a homogeneous roughness. Scanning electron microscopy evinced a porous microstructure that can stimulate the growth of the bone tissue into pores. The presence of the PO 4 3 - anions promotes the electrostatic bonds between the nanolayer and different species from the biofluid, namely, osteoinduction. The anodic oxidation nanolayer improved all electrochemical and corrosion parameters conferring superior protection to the substrate by its higher resistance to the ion migration. Impedance spectra showed that the electrodeposited nanolayer is formed by an inner, dense, barrier layer and an outer porous layer. The nanolayer thickened in time, namely, is bioactive. The oxidized nanolayer is able to protect the alloy from ion release, to assure long-term corrosion resistance, to minimize adverse reactions, to increase alloy bioactivity, to stimulate cell growth, and to favor osseointegration.