The Galvanic Corrosion of Steel in Sodium Chloride Solution

This paper describes a study of the galvanic corrosion of steel coupled to noble metals in sodium chloride solutions. The corrosion behavior was measured by the amount of galvanic current with a zero impedance ammeter and by the weight loss. The galvanic current flowing from the steel is not related to the cathodic metal, but is proportional to the area ratio of the steel to the cathodic metal. The galvanic current density flowing in the cathodic metal is not related to the area ratio or to the nature of the cathodic metal, and approaches the limiting current density for oxygen reduction. Further, local action currents on the steel depend on the area ratio of the steel to the cathodic metal and they are not related to the concentration of sodium chloride in neutral solution.