Electrochemical Oxidation of Ti-Grad 23 Alloy for Biomedical Applications: Influence of TiO₂ Formation on Their...

In this study, the influence of the electrochemical oxidation process on Ti-Grad 23 alloy (Ti6Al4V ELI) in 1 M H₃PO₄, under applied voltages between 200 and 275 V, at a constant time of 1 min, is analyzed. The structural, morphological, and wettability properties of the TiO₂ anodic layers obtained were investigated by X-ray diffraction (XRD), energy dispersive electron microscopy (SEM-EDS), contact angle measurements, and chemical corrosion. XRD analysis showed the development and intensification of anatase and brookite phases, with increased crystallite size after electrochemical oxidation. SEM/EDS characterization confirmed the formation of an inhomogeneous porous TiO₂ layer, with pore diameters ranging from 98 to 139 nm and a significant increase in oxygen content. Contact angle measurements demonstrate enhanced hydrophilicity for all oxidized samples, with progressively lower values as the applied voltage increased. Chemical corrosion tests in Ringer solution and Ringer + 40 g/L H₂O₂ indicated that oxidized surfaces maintain structural stability in physiological media, whereas exposure to oxidizing environments induces partial pore closure and crack formation due to localized corrosion. The optimal anodizing condition was identified at 200 V for 1 min, yielding a uniform distribution of pores and improved morpho-functional characteristics suitable for biomedical applications. The optimal electrochemical oxidation conditions were identified at 200 V for 1 min, ensuring a uniform pore distribution.