Effect of sulfate and chloride ions on the electrochemical behavior of iron in aqueous phosphate solutions

The electrochemical behavior of iron in aqueous phosphate solutions (0.005–0.1M) of pH∼8 at room temperature was investigated with an emphasis on the effect of chloride and /or sulfate ions on the initiation of the localized attack. Electrochemical techniques were complemented by SEM microscopy, FTIR, X-ray fluorescence analysis and ICP measurements. It has been shown that phosphate ions are very effective inhibitors against localized attack, and in the presence of sulfate ions still show an effect very similar to that of phosphate ions in the active–passive dissolution peak region.