The Embedding of Doped Fluoride PEG in the Polypyrrole Coating on AZ31 and the Investigation of Its Corrosion Behavior

Polypyrrole modified coatings were coated by ammonium bifluoride doped in the polyethylene glycol (Doped Ppy) on AZ31 alloy using cyclic voltammetry. The result of nuclear magnetic resonance showed that fluoride doping occurred in the glycol molecule. Corrosion performance of the coatings was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization in 0.05 M NaCl solution. Corrosion current density of polypyrrole modified coatings (Doped Ppy) was calculated about 5 µA.cm-2 , which was 5 times lower than the coating with discrete PEG and fluoride ions. It was observed that the modified polypyrrole coatings shows the highest corrosion resistance due to the synergism effect of fluoride and polyethylene glycol. Charge transfer resistance (Rdl) of polypyrrole coating with fluoride and PEG and polypyrrole coating containing ammonium bifluoride doped in the PEG was 5950 and 10050 Ω.cm2 , which was higher about 2.5 and 4.5 compared polypyrrole coating with Rdl of 2250 Ω.cm2 .