Sodium Nitrite as a Corrosion Inhibitor for Mild Steel

Abstract

The effect of sodium nitrite on the corrosion rate of mild steel in chloride and sulfate media has been investigated. The results obtained support the view that passivity in these systems results from an oxide film maintained in a state of dynamic equilibrium, with protection dependent upon the rate of protective oxide film formation exceeding the rate of film deterioration. The data also indicate that the basic function of sodium nitrite is to assist the cathodic process and thereby provide that current necessary to form a protective oxide film, or expressed differently, to provide that current necessary to polarize above the critical potential for passivity.