Electrochemical property analysis of SiO₂-Al₂O₃-coated steel by electrochemical impedance spectroscopy

The purpose of this paper is to investigate the corrosion resistance of SiO₂-Al₂O₃ coating on mild steel.

SiO₂-Al₂O₃ was coated using sol-gel method, and electrochemical measurements were applied to assess the performance of the coated steel.

The main conclusion is that SiO₂-Al₂O₃-coated specimens acquired a higher corrosion resistance than that of uncoated specimen. i_corr values of the coated specimens were between 12 and 14 times smaller than those of uncoated specimen. The coated specimens exhibited a higher R_cor value at electrochemical impedance spectroscopy analysis. The high values of R_cor and low values of CPE_dl observed within the SiO₂-Al₂O₃-coated samples imply an improved anti-corrosion capability.

In this work, there are three points of originality. First, steel specimens were coated with ormosil-based solution by applying sol-gel dip coating method. Second, both SiO₂ and Al₂O₃ coatings were applied simultaneously at a considerably low temperature, i.e. 200 °C. Finally, the performance of the coated materials against wet corrosion was improved significantly.