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

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.

► Protection of galvanized steel from corrosion in NaCl solution using coating films. ► Effect of pretreatment samples (before coating) on protective efficiency. ► Pretreatment samples in H2SO4/H2O2-mixture show higher protective efficiency. ► Modification of phytic acid self-assembled monolayer using some cations and thiols. ► Dimercaptopropanol conversion coating layer exhibit higher protective efficiency.