The effect of anodic inhibitors on corrosion behavior of electrodeposited nanocrystalline iron in chloride media

Direct electrodeposition was used to produce nanocrystalline (NC) iron from iron sulfate electrolyte with saccharin and sodium citrate as additives particle refiners. Surface morphology, grain size and crystal structure of deposits were examined by high resolution scanning electron microscope (HRSEM) and X-ray diffraction analysis (XRD). Electrochemical behavior of the electrodeposited NC iron in comparison with coarse-grained (CG) iron in presence of anodic inhibitor (Na2MoO4) was investigated in 30 ppm NaCl + 70 ppm Na2SO4 aqueous solution using electrochemical impedancespectroscopy (EIS) and potentiodynamic polarization techniques. The results showed that the corrosion behavior of NC and CG iron depends on oxygen content in the neutral aqueous chloride media. Corrosion resistance of nanocrystalline iron in presence of sodium molybdate and oxygen increased up to 97.4%. This is probably because of the higher adsorption of corrosion inhibitors due to the increase in the fraction of grain boundaries in NC iron. However, the results showed that decreasing the grain size to nano size did not improve the corrosion resistance of the electrodeposited NC iron.

Keywords:

Nanocrystalline iron , Coatings , Electrochemical techniques , Corrosion , Inhibitors