Inhibition effects of inorganic multivalent cations on corrosion of Fe in an aerated 0.5 M sodium sulfate (Na2SO4) solution were investigated using polarization measurements. The cations formed deposit layers of their hydroxides on the Fe surface by reactions with hydroxide ions (OH–) afforded through the cathodic process of Fe corrosion. Some layers on the surface were analyzed by x-ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA). Since the cations suppressed the cathodic process but stimulated the anodic one, their inhibition efficiencies were not markedly high. Inhibition effects of the cations on the cathodic process were related closely to the hard and soft acids and bases (HSAB) principle because the effect increased with the hardness of a cation as an acid.

Subject
Pits, Hydroxides, Sodium sulfate, Oxide layers, Anode surfaces, X-ray spectroscopy, Polarization curves, Surface analysis, Corrosion inhibitors, Surface layers, Risk reduction, Cations, Electrodes
Keywords:
acids, bases, electron probe microanalysis, inhibition, inorganic cations, iron, multivalent cations, oxides, polarization, sodium sulfate
NACE International
1999
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