Protection of galvanized steel from corrosion in NaCl solution by coverage with phytic acid SAM modified with some cations and thiols

A.-R. El-Sayed, U. Harm, K.-M. Mangold, W. Fürbeth

Corrosion Science, 2012, 55, 339-350 doi:10.1016/j.corsci.2011.10.036

Abstract

Ultrathin films of various compounds were prepared on galvanized steel coated with both phytic acid (PA) and diethylene triamine pentamethane phosphonic acid (DETPMPS) self-assembled monolayers (SAM), and in the presence of small amounts of special salt (MnSO4 or Cr(NO3)3). Phytic acid and phytic acid–Mn2+ were modified with dithio-oxamide (DTOA) and 2,3-dimercapto-1-propanol (DMP). Tafel plots and impedance measurements were used. Most investigated conversion coatings of the samples pretreated only in H2SO4/H2O2-mixture, showed that the protective efficiency values (P%) are greater than those of pretreated in both hot alkaline solution and H2SO4/H2O2-mixture.

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