Electropolymerized conducting polyaniline coating on nickel-aluminum bronze alloy for improved corrosion resistance in marine environment

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 691; p. 133909
• Main Authors: Amegroud, Hicham, Boudalia, Maria, Elhawary, Maha, Garcia, Anton José, Bellaouchou, Abdelkbir, Amin, Hatem M.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.06.2024
• Subjects: AFM, Corrosion protection; Conducing polymers; Electropolymerization; Nickel-aluminum bronze alloy; Raman spectroscopy; Conducing polymers; Nickel-aluminum bronze alloy; Raman spectroscopy; Electropolymerization; AFM, Corrosion protection
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2024.133909

Corrosion of metals in marine environments is a vital problem with significant negative economic impacts and coating is an effective measure of protection. In this work, polyaniline (PANI) conducting polymer was deposited as a protective layer on a nickel-aluminiumbronze (NAB) alloy using the galvanostatic electropolymerization method at different current densities. The deposited coating was characterized by various techniques such as FTIR and SEM. To evaluate its effectiveness in corrosion protection, the anticorrosion properties of different PANI coatings were evaluated in a 3.5 wt% NaCl solution by both potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The electrochemical results revealed that PANI coatings acted as a barrier towards the corrosive species and provided significant corrosion resistance to NAB degradation, with an inhibition efficiency of about 93% and a mixed-type inhibition behavior with cathodic predominance. Furthermore, corrosion protection was found to be dependent on the coated film properties and the optimum corrosion inhibition was achieved under the test conditions for films deposited at a current density of 5 mA cm-². Moreover, Raman spectroscopy confirmed the presence of the partially oxidized conductive polyaniline, the emeraldine form and its polaron structure, on the alloy surface. In addition, atomic force microscopy (AFM) was used to monitor the changes in the microstructure of the coating after exposure to the saline environment and demonstrated the formation of a robust coating with a significantly lower (5 times) surface roughness for the coated alloy than the uncoated surface after immersion. Overall results strongly support the potential of PANI for corrosion protection of the NAB alloy. [Display omitted] •Adherent PANI film was successfully synthesized on nickel-aluminium alloy (NAB) by galvanostatic electropolymerization.•The performance of PANI coated-NAB alloy was evaluated in chloride-containing environment.•The optimized inhibition efficacy of 92% was achieved for coatings synthesized at 5 mA cm−2.•Raman and FTIR spectroscopy revealed the presence of PANI in the conductive emeraldine state.•AFM demonstrated a much even and smoother surface of the coated NAB compared to the unprotected one.