Corrosion protection of AZ91D magnesium alloy BY a duplex coating?

A. D. FORERO LÓPEZ; I. L. LEHR; S. B. SAIDMAN

Congreso; XI Congreso Lationamericano de Corrosión (LatinCorr 2018); 2018

Magnesium and its alloys have been intensively studied as biodegradable materials. However, a serious limitation for the wide spread use of several Mg alloys is their susceptibility to corrosion [1-2]. In order to improve the corrosion resistance of magnesium alloy AZ91D, a duplex coating was formed under potenciostatic conditions. An adherent and uniform first layer was formed by anodisation at low potentials in molybdate solutions. The outer layer was a polypyrrole (PPy) film obtained in a 0.1 M sodium salicylate solution. This film showed the typical cauliflower morphology of the polymer.The coatings were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). 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 obtained results indicate that the presence of the bilayered coating improves the corrosion resistance of the bare substrate. The electrode covered by the duplex coating was modified by silver particles. The modified bilayer showed a good antibacterial activity.