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.