Anodic Alloys Degradation Exposed to Different Flow Conditions in Natural Seawater

Abstract

Flow conditions can be harmful to the performance of the sacrificial anodes exposed to the marine environment. The anodic alloy used for protection to the metal structures in this environment, can be affected by the high chloride concentration and other substances that accelerate the electrochemical corrosion phenomenon. The anodic alloys used in the marine environment are zinc and aluminium based alloy. Different tests to evaluate the electrochemical performance of three alloys, Zn, Al-Zn-Mg and Al-Zn-In, were carried out. A rotating cylinder electrode (RCE) was used in order to control the hydrodynamic conditions. The electrochemical techniques used in the corrosion studies were: corrosion potential (Ecorr), linear polarization resistance (Rp), potentiodynamic polarization curves and Electrochemical Impedance Spectroscopy (EIS) and natural seawater was used as the test solution. Cathodic kinetics information was obtained in the electrochemical analysis results where, it shows the effect of the Rp values versus rotational speed, as the rotational speed increased the Rp values decreased. In addition, a localized corrosion form was found in the corrosion process.