Electrochemical Deposition of Hydroxyapatite on Stainless Steel Coated with Tantalum/Tantalum Nitride Using Simulated Body Fluid as an Electrolytic Medium

In the present work the electrochemical deposition of hydroxyapatite using simulated body fluid (SBF) as an electrolytic medium was carried out on Ta and Ta/TaN coatings on BIOLINE stainless steel SS316LVM (SS). The electrochemical deposition performed on each substrate for 3000 and 6000 s, at different potentials were determined from cyclic voltammetry. The best conditions found were −1.4 V for bare SS and −1.7 V for Ta/TaN coating. The structural characterization was carried out by SEM, FTIR, XRD, and contact angle measurements. The electrochemical characterization was done by electrochemical impedance (EIS), which allowed us to know the capacitive and resistive character of the substrates. The substrate (Ta/TaN)/SS at −1.7 V 6000 s presented the largest formation of a nonstoichiometric hydroxyapatite with a uniform distribution on the substrate, implying that Ta–OH is formed on the tantalum metallic surface, due to formation of the passivation layer of tantalum oxide. These groups attract Ca²⁺ ions and PO₄³⁻ ions absorbed on the surface will form the precursors of the apatite crystals that finally transform to hydroxyapatite. The electrodeposition of HAp the double layer Ta/TaN resulted in a more uniform and denser layer than SS alone.