In situ micro-Raman spectroscopy to investigate pitting corrosion product of 1024 mild steel in phosphate and bicarbonate solutions containing chloride and sulfate ions

摘要

The nature of the corrosion products generated by localized attach on 1024 mild steel have been investigated in the presence of chloride and/or sulfate ions in bicarbonate and phsophate aqueous solutions. A spectroelectrochemical cell was used for in situ measurements of the Raman spectra of the corrosion products generated during pitting. These products were identified as the so-called green rust componds. The assignment of the hydroxyl groups in green rust is confirmed by isotopic substitution. The composition of the green rust generated in bicarbonate or phosphate solution containing chloride and/or sulfate ions has been determined. A correlation between the green rust composition and the electrochemical behaviour after the initiation of pitting has been noted and discussed.