Investigating the effect of salicylate salt in enhancing the corrosion resistance of AZ91 magnesium alloy for biomedical applications

Abstract

The pretreatment process plays a vital role in the development of a robust protective layer on magnesium alloys. This work presents a novel insight into the pretreatment of magnesium alloy AZ91 in alkaline silicate solution by anodic oxidation in the presence of C7H5NaO3 (sodium salicylate) to enhance surface resistance and introduce a passive biolayer. The electrochemical corrosion behavior of protective layers prepared at different voltages was evaluated by electrochemical impedance spectroscopy (EIS) in SBF solution. The Nyquist impedance plots for anodized films, which consist of a mixture of magnesium silicate and salicylate, indicate a significant corrosion protection ability of the layers formed under optimized conditions; an increase of the real impedance from the value of ∼2 kΩ.cm2 for the bare alloy surface to about 10-12 kΩ.cm2 for the anodized film can be observed. The results indicate that surface modification by anodizing in silicate electrolyte in the presence of sodium salicylate is an alternative pretreatment to improve the corrosion resistance of AZ91.