| In this study, A. C. Impedance spectra of various surface treated sheets-EG(electrogalvanized sheet), Cr(chromated sheet) and AF(anti-finger printed sheet) were measured at cathodic polarization potential in the solution of 0.2% NaCl. In order to evaluate corrosion resistance, Rp values measured through A. C. impedance spectra at the different cathodic polarization (O.C.P., oxygen reduction and hydrogen evolution potential), were compared to the result of salt spray test. Rp values measured at the dissolved oxygen reduction polarization was reliable and consistant with the results of SST. As impedance spectra was analyzed through several equivalent circuit models with transfer resistance and diffusion impedance, corrosion resistance could be predicted in a short time. |
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