Effect of chlorine and ammonia residuals on the corrosion of copper-base and nickel-base alloys in seawater using electrochemical impedance spectroscopy

Electrochemical impedance spectroscopy (EIS) was used to study the effect of residual chlorine and ammonia on the corrosion behaviour of Carbon steel, UNS⁽¹⁾ C71500 and UNS N06030 in seawater. Typical interfacial impedance results showed impedance slightly shifting to resistive behaviour for the three alloys upon the addition of 5 ppm of chlorine to seawater. However, slight shift of the impedance towards less resistive behaviour for the three alloys was observed when 5 ppm ammonia was added to the seawater.