Electrochemical Characterization of the Structural Metals Immersed in Natural Seawater: <i>In Situ</i> Measures

Abstract

This work presents the electrochemical corrosion results of the structural metals, aluminium (Al), brass and copper (Cu), immersed in coastal waters of Veracruz Port in Mexico at room temperature, atmospheric pressure and eight weeks of the exposition time. The electrochemical technique used was electrochemical noise (EN). A typical three-electrode electrochemical cell was used. Where the reference electrode was the silver/seawater (Ag/SW) and two nominally identical metallic samples were used as working electrodes (WE1 and WE2). The metallic samples of Al, brass and Cu were used as working electrode. The potential and current fluctuations were measured simultaneously between the two working electrodes (current measured) and the Ag/SW electrode (potential measured). The electrochemical noise measurements (ENM) were analysed by three different methods: Potential and current versus time (transients), Localization Index (LI) and Electrochemical Noise Resistance (Rn). The results shown a good correlation between the superficial analysis and the results obtained by the ENM. In addition, Cu presents the highest corrosion rate and, a corrosion attack was obtained by localization index; this behaviour was confirmed by superficial analysis.