Corrosion behaviour of Ppy coating modified by PEG doped ammonium bifluoride
In a new study, polypyrrole (Ppy) coatings embedded by polyethylene glycol (PEG) doped ammonium bifluoride (doped Ppy) was deposited on the AZ31 Mg alloy using cyclic voltammetry.
Fluoride-nuclear magnetic resonance (F-NMR), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC) results showed that the doping of fluoride in the polyethylene glycol molecule was implemented. Corrosion performance of the doped Ppy coatings was assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation techniques in 0.05 M NaCl solution.
Doped Ppy coatings with higher corrosion resistance
Field emission scanning electron microscopy (FESEM) and energy-dispersive x-ray spectroscopy (EDS) showed that doped Ppy coatings possessed higher corrosion resistance than that of Ppy coating. Charge transfer resistance of doped Ppy coating measured about 2 and 5 times higher than un-doped Ppy and Ppy coatings, respectively which were associated to the synergistic behaviour of fluoride with polyethylene glycol as well as its release to the anodic zones.
The study is published in: Progress in Organic Coatings Volume 134, September 2019, Pages 22-32.
