THE EFFECTS OF BICARBONATE ON THE CORROSION AND PASSIVATION OF IRON

Dissolution in the active and prepassive regions is accelerated by bicarbonate. A mechanism is proposed for the process. Pitting is observed under conditions where dissolution as the complex occurs. Raising the potential into the passive regions where Fe(111) forms in the film prevents complexing and anodically protects the metal from pitting. Possible implications of complex formation in the stress corrosion cracking of mild steel in bicarbonate electrolytes are discussed.