Improvement in the corrosion protection and bactericidal properties of AZ91D magnesium alloy coated with a microstructured polypyrrole film

In this work hollow rectangular microtubes of polypyrrole (PPy) films were potentiostatically electrodeposited on magnesium alloy AZ91D in salicylate solution. The substrate was previously anodized under potentiostatic conditions in a molybdate solution in order to improve the adherence of polymer. Finally the duplex film was modified by the incorporation of silver species. The obtained coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopies (XPS) and the antimicrobial activity against the bacteria Escherichia coli was evaluated. The corrosion protection properties of the coatings were examined in Ringer solution by monitoring the open circuit potential, polarization techniques and electrochemical spectroscopy (EIS). The duplex coating presents an improved anticorrosive performance with respect to the PPy film. The best results concerning corrosion protection and antibacterial activity were obtained for the silver-modified composite coating.