Electrochemical study of the corrosion behaviour of zinc treated with a new organic chelating inhibitor

The effect of a new organic molecule with chelating groups on the corrosion behavior of zinc was investigated. Electrochemical studies of the zinc specimens were performed in aerated aqueous solution (0.2 M Na2SO4 + 0.2 M NaCl, pH 6) by means of electrochemical impedance spectroscopy (EIS), as well as polarization curves using a rotating disk electrode. The treatment was achieved by immersion in solutions of variable concentration of the organic molecule and for different immersion times. The influence of the treatment bath temperature was also studied. The recorded electrochemical data showed that the corrosion resistance of the treated samples was greatly enhanced when compared to the untreated zinc. Moreover, the treatment induced a basic modification of the cathodic corrosion behavior of zinc decreasing the electron transfer rate. The corrosion inhibition could be explained by a chelation reaction between zinc and organic molecule and the formation of a protective organometallic layer on the metal surface. Fourier Transform Infrared Spectroscopy (FT-IR) was applied in order to investigate this layer. (C) 2000 Elsevier Science Ltd. All rights reserved.