Electrochemical evaluation and surface study of magnetite/PANI nanocomposite for carbon steel protection in 3.5% NaCl

•Polyaniline and magnetite (Fe3O4) nanoparticle (Fe3O4/PANI) nanocomposites were prepared.•Prepared Fe3O4/PANI nanocomposites were characterized by FT-IR, XRD, TEM, SEM and EDXA.•A thin layer of the Fe3O4/PANI nanocomposites was used to coating carbon steel as corrosion protector film in NaCl 3.5%.•A 100 mg/L of Fe3O4/PANI (1:1) nanocomposite in 60 mine can formed a protective layer with protection efficiency of 96.8%.•Ability of proposed coating as an anticorrosive layer was further proofed by using SEM and EDXA.

Herein, a nanocomposite of polyaniline and magnetite (Fe3O4) nanoparticles (Fe3O4/PANI) was prepared through a two-step oxidative polymerization in different mass ratio as 1:1, 1:2 and 2:1. Prepared Fe3O4/PANI nanocomposites were characterized by FT-IR, XRD, TEM, SEM and EDXA. A thin layer of the Fe3O4/PANI nanocomposites was used to coating carbon steel as corrosion protector film in NaCl 3.5%. Anti-corrosion performance of the Fe3O4/PANI nanocomposites was investigated through electrochemical techniques such as open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance (EIS). Observed results showed a dramatic shift in corrosion potential and a decrease in cathodic and anodic reactions rate in Tafel plots. Also, EIS data showed charge transfer resistance was increase after coating the carbon steel with Fe3O4/PANI nanocomposite. Affecting parameters like mass ratio, amount of nanocomposite, and film formation time, were optimized. Our electrochemical results showed that 100 mg/L of Fe3O4/PANI (1:1) nanocomposite in 60 mine can achieved to protection efficiency of 96.8% in 3.5% NaCl. Finally ability of proposed coating as an anticorrosive layer was further proofed by using surface methods i.e. SEM and EDXA. Observed results are presented and discussed.