Production of an eco-friendly anti-corrosion ceramic base nanostructured hybrid-film based on Nd (III)-C7H6N2 on the mild steel surface; Electrochemical and surface studies

The objective of this research is to study the impact of BI (Benzimidazole) addition on the surface characteristics and corrosion resistance of the Nd conversion coating. Field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), attenuated total reflection (ATR), X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM) and contact angle measurements were employed to study the microstructure, functional groups, chemical composition, topography and the surface chemistry, respectively. Also, the electrochemical impedance spectroscopy (EIS) and polarization experiment were utilized to survey the corrosion resistance of the untreated and treated samples, respectively. Results showed uniform precipitation of Nd layer and Nd-BI complexes over the related surfaces and it was found that BI has a nucleation site creation role. XPS studies revealed that neodymium is present on the Nd-BI sample in both trivalent and tetravalent state. The roughness of the Nd-BI sample was lower than Nd sample due to the anodic sites covering by Nd-BI complexes. Nd-BI sample showed the highest work of adhesion due to the lowest contact angle. Corrosion studies revealed the effective protection provided by Nd-BI complexes. The charge transfer resistance of the blank sample was 1810 Omega.cm(2). Adding 1000 ppm Nd cations to the spraying solution increased the resistance to 1920 Omega.cm(2), while in the presence of 1000 ppm from both Nd and BI, the resistance reached 2649 which is an acceptable value by considering the nature and application of the coating. The corrosion current density values for the blank, Nd and Nd-BI samples found to be 10.83, 8.51 and 6.43 mu A/cm(2), respectively. (C) 2019 Elsevier Ltd. All rights reserved.