Evaluating the anti-corrosion behavior of hybrid zirconium-polyethyleneimine layer by mean of electrochemical method

Abstract

Zirconia conversion coating as an eco-friendly treatment technology is the most promising method of replacing traditional phosphating technology. A new kind of zirconia/polyethyleneimine composite coating was fabricated on carbon steel. Potentiodynamic polarization, electrochemical impedance spectroscopy and salt spray test analyses were used to evaluate the corrosion behavior of samples in 3.5wt% NaCl solution. Scanning electron microscope was used to characterize the surface morphology of the samples. Results showed that zirconia coating after polyethyleneimine (PEI) treatment generated a protective layer through combination of physisorption and chemisorption, which enabled the new composite coating to perform much better than single zirconia coating. The zirconium-polyethyleneimine layer demonstrated the best anti-corrosion performance with the lowest corrosion current and highest polarization resistance. Overall, this study established a promising anticorrosion method involving the production of zirconia coating as an interlayer prior to forming PEI coating on a substrate.