Corrosion behaviour of polypyrrole-coated WE43 Mg alloy in a modified simulated body fluid solution

The corrosion behaviour of PPy-coated WE43 Mg alloy in a simulated body fluid solution with daily electrolyte renewal is investigated by electrochemical, hydrogen evolution and analytical techniques. It is shown that the PPy coating effectively contributes to a decrease in the corrosion rate of WE43 Mg alloy and production of H-2 gas. An increase in the PPy coating protective properties observed after every electrolyte renewal is attributed to: 1) a decrease in the coating conductivity by the adsorption of CO2 species, and 2) substrate/coating decoupling due to uncompensated coating positive charging and misalignment of the substrate and coating Fermi levels.