Enhanced surface protective performance of electrochemically synthesized polypyrrole-CeO_2 nanocomposite coatings on AA2024 alloy

摘要

A facile approach based on electrochemical polymerization was used to synthesize polypyrrole/CeO_2 (PPy/CeO_2) nanocomposite on AA2024 alloy surface. CeO_2 nanoparticles embedded in the PPy matrix are evidently observed from the FESEM micrographs with EDX analysis. IR and UV-Vis spectroscopy was also used to characterize the synthesized PPy/CeO_2 nanocomposite. Raman spectrum reflects the interaction between the π-conjugated structure of PPy and the CeO_2 nanoparticles in the investigated nanocomposite. TGA thermogram reveals improved thermal stability of the synthesized nanocomposite and used to determine the amount of nano ceria incorporated in PPy matrix. Electrochemical corrosion behavior of the coated alloys in 3.5% NaCl solution was examined using potentiodynamic polarization and electrochemical impedance spectroscopic measurements. From these studies, a larger shift of E_(corr) in the positive direction was obtained with high amount of CeO_2 in nanocomposite and the maximum corrosion protection efficiency (99.1%) was obtained by incorporating 3% CeO_2 nanoparticles in PPy coatings.