Monitoring and Evaluation of Corrosion at the Interface of Zirconium Alloy Biomaterials Under Simulated Oxidative Biological Environment

The present work investigates the electrochemical behavior of the Zr2.5Nb alloy in a biomedical context, emphasizing the influence of electrochemical oxidation treatment on its stability in simulated physiological environments. The alloy samples were oxidized in 1 M H₂SO₄ under controlled voltages (200-275 V) and times (1 min), identifying 200 V-1 min as the optimal condition for obtaining a uniform porous oxide layer with an average pore diameter of ~90 nm. The corrosion resistance was evaluated using open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) in Ringer's solution and Ringer's solution containing 40 g/L H₂O₂ to simulate physiological and inflammatory conditions. Electrochemical tests revealed that electrochemically oxidized samples exhibited a polarization resistance up to 14.78 MΩ·cm², about 26 times higher than that of the untreated alloy (0.56 MΩ·cm²). After 77 h of immersion, the oxidized alloy maintained a high resistance (17.54 MΩ·cm²), confirming long-term stability. Scanning Electron Microscopy (SEM-EDX) and X-Ray Diffraction (XRD) analyses highlighted significant increases in oxygen content and the transformation from the monoclinic baddeleyite to the cubic arkelite phase of ZrO₂, contributing to enhanced corrosion resistance. These findings demonstrate that controlled electrochemical oxidation significantly improves the durability of Zr2.5Nb alloy in oxidative environments, supporting its potential for long-term biomedical implant applications.