The inhibition effects of chromate-free, anion inhibitors on corrosion of zinc in aerated 0.5 M NaCl

Abstract

The inhibition effects of chromate-free, environmentally acceptable anion inhibitors were examined on corrosion of zinc in an aerated 0.5 M NaCl solution by polarization measurements. Sodium silicate Na 2Si 2O 5 and phosphate Na 3PO 4 were remarkably effective on zinc corrosion, exhibiting high inhibition efficiencies around 90%. Pitting corrosion was not observed on the zinc electrode inhibited with these anions. The zinc surfaces treated with these anions in the solution were analyzed by X-ray photoelectron spectroscopy and electron-probe microanalysis. The inhibition efficiencies of molybdate MoO 4 2− and tetraborate ions B 4O 7 2− were not markedly high and phosphonates were less effective inhibitors.