Corrosion Resistance of Niobium-Coated Carbon Steel

Abstract

In this work, the effectiveness of niobium coatings for the corrosion protection of carbon steel was studied. Three niobium resins, containing different molar proportions of citric acid:ethylene glycol, were coated separately onto samples of carbon steel (SAE 1020). The niobium layers were obtained by the polymeric precursor method (Pechini). Potentiodynamic polarization curves (anodic and cathodic) and electrochemical impedance spectroscopy were used to evaluate the corrosion resistance of the niobium-coated carbon steel samples in a 0.5 mol L−1 NaCl electrolyte solution. X-ray diffraction analysis of the niobium layers showed that they are composed of the niobates: NbO, NbO2 and Fe0.998Nb0.002. Surface observation by scanning electron microscopy revealed a uniformly deposited niobium coating on the surface. The electrochemical results showed that niobium was effective in the corrosion protection of the carbon steel substrate. The results also suggested that niobium can be coated onto the substrate to form a layer with advantageous corrosion properties.