Effect of Oxygen Concentration and pH on Electrode Potential of Stainless Steels and Operation of Microcouples

Abstract

Abstract Using Russian steels of 13 Cr and 18–9 analyses in general experiments are conducted varying pH and oxygen concentrations in sea water to determine the relative effect of these variables on corrosion rates in crevices. Effect of oxygen concentrations in the range 1–9 mg/1 and pH 8.3 to 2.3 are reported. Changes in pH were found to strongly and changes in oxygen concentration weakly influence the corrosion rate. Authors postulate that anodic passivity is effected after application of tenths of a milliampere per square centimeter whereas when the pH in the anodic space is lowered, critical current density required for passivation increases 40–50 fold. Heat treatment of the steel does not influence electrode potentials when solution pH is lowered.