Corrosion resistance of chromium and zinc platings by EIS

Abstract

The corrosion behavior of chromium and zinc industrial coatings was investigated in 3%wt NaCl solution using electrochemical impedance spectroscopy technique. In order to determine the mechanisms of protection and failure of these coatings, we have correlated the polarization resistance in time function, with the morphology and chemical composition. To do this, we characterized the microstructure of the coatings by scanning electron microscopy, the crystalline phases with X-ray diffraction and chemical composition, before and after exposure to a corrosive environment, by X-ray photoelectron spectroscopy and Auger electron spectroscopy.Overall, both coatings (Cr and Zn) showed degradation with the immersion time, due to microstructure defects, however, the protective and failure mechanisms are different for each system. These details are discussed in this research.