The electrochemical and sonoelectrochemical synthesis of polypyrrole (PPy) on St-12 steel was achieved in an oxalic acid medium by using a galvanostatic method with a current density of 4 mA/cm2. Direct application of low-frequency ultrasound led to more compact and more homogeneous surface structures for PPy. The corrosion behavior of the coatings was studied through open circuit potential-time curves, potentiodynamic polarization technique, and electrochemical impedance spectroscopy measurements in NaCl 3.5% solution. The Kramers–Kronig transformations were applied to evaluate the validity of the impedance data. The results showed that the coating resistance (Rcoat), corrosion resistance (Rcorr), and warburge resistance of ultrasonically prepared samples were higher than that of nonultrasonically synthesized PPy. With the help of scanning electron microscopy, we investigated the effects of the ultrasonic irradiation on the morphology and the results reveal that the sonoelectrochemical synthesis method yielded strongly adherent and smooth coats.
کلید واژگان :Coatings, Conducting polymers, Electrochemistry, Morphology, Polypyrrole
ارزش ریالی : 600000 ریال
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