The inhibition effects of cation inhibitors on corrosion of zinc in aerated 0.5 M NaCl

This investigation deals with inhibition of zinc corrosion in an aerated 0.5 M NaCl solution by environmentally acceptable cation inhibitors, Al3+, La3+, Ce3+ and Ce4+. The inhibition efficiencies of these cations were determined by polarization measurements of a zinc electrode in the solution. The efficiencies of Ce3+ and La3+ were high, more than 90% but those of other cations were negative, indicating stimulation of zinc corrosion. X-ray photoelectron spectra for the zinc surface treated in the solution containing Ce3+ revealed that a thick protective layer composed of Ce(OH)(3), Ce2O3 and small amounts of Zn(OH)(2) and ZnO formed on the surface and there was no chloride ion within the layer. Processes of the layer formation on the surface were discussed based on these results. (C) 2001 Elsevier Science Ltd. All rights reserved.