Surface chemistry, film morphology, global, local electrochemical behavior and cytotoxic response of anodized AZ31B magnesium alloy

Abstract

In this work, we provide a detailed investigation on the correlation between the surface chemistry, film morphology, global and local electrochemical behavior of the AZ31B alloy anodized under different constant current densities. The anodizing treatment was carried out in 1.0 M NaOH and 0.5 M Na2SiO3 solution, using three different current densities, 5 mA.cm-2 , 10 mA.cm-2 and 20 mA.cm-2 . The surface morphology and thickness of the anodized layers were examined by scanning electron microscopy. The surface chemical states were assessed by X-ray photoelectron spectroscopy. The global electrochemical behavior was investigated by electrochemical impedance spectroscopy and potentiodynamic polarization. The local electrochemical activity was monitored by scanning electrochemical microscopy and scanning Kelvin probe. In vitro biocompatibility was assessed by cytotoxicity tests. The results indicated a marked influence of the anodizing current density on the surface morphology and global electrochemical behavior of the treated samples. The surface chemistry, in turn, was little affected by this parameter. The best corrosion resistance was obtained for the samples anodized at 20 mA.cm-2