Using electrochemical Impedance spectroscopy to evaluate the corrosion behavior of pore copper in simulated rainwater containing typical pollutants of the cities of Rio de Janeiro and Sao Paulo

摘要

Most of the metallic outdoor monuments are exposed to urban atmosphere and their corrosion behavior under these particular conditions must be understood. The aim of this work Is to use EIS as the central technique to evaluate the effects of the main pollutants encountered in the atmosphere of Rio de Janeiro and Sao Paulo in the electrochemical behavior of pure copper. For this, polished samples of the metal were exposed to simulated rainwater of both cities, and their electrochemical response was monitored with time under permanent and intermittent immersion conditions. Electrochemical measurements were complemented with the evaluation of the anodic and cathodic behavior of the samples. The composition of the corrosion products layers was evaluated by XRD. EIS analyses clearly Indicated the development of a corrosion product layer with immersion time, Independently of the electrolyte composition, which evolution was extremely dependent on the electrolyte composition as well as on the exposure condition: permanent immersion or intermittent exposition. In the former exposure condition a porous layer seems to be developed, while intermittent exposition seems to contribute for the layer consolidation and compactness.