Electrochemical Behavior and Corrosion Study of Electrodeposits of Zn and Zn-Fe-Co on Steel
- 1 Departamento de Física e Química, Universidade Estadual Paulista, Campus de Guaratinguetá, Guaratinguetá, Brazil.
- 2 Departamento de Física e Química, Universidade Estadual Paulista, Campus de Guaratinguetá, Guaratinguetá, Brazil.
- 3 Departamento de Física e Química, Universidade Estadual Paulista, Campus de Guaratinguetá, Guaratinguetá, Brazil.
Abstract
From industrialized baths, free of cyanide, the corrosion behavior of electrodeposits of zinc and zinc alloys was studied by means of electrochemical tests in aerated solution of 3.5% (0.6 M) NaCl at pH 8.2. In literature, several studies are found about zinc coatings and zinc alloys, for example, Zn-Ni and Zn-Co, nevertheless there is little about the ternary alloy Zn-Fe-Co. The Fe presence in the alloy results in a good adhesion to the substrate and allows application of these materials at higher temperatures. The electrochemical tests were carried out by obtaining open circuit potential curves with immersion time, potentiodynamic polarization curves and cyclic voltammetry. From the obtained results, the large potential differences observed between the steel and the electrodeposits showed that the last protect the substrate, acting as a sacrifice metal. The tests disclosed similar behaviors in both the current densities and the corrosion potential for electrodeposits of Zn and Zn-Fe-Co. After chromate passivation process, a significant decrease in corrosion density was noted for Zn and when the system was de-aerated there was change in the cathodic process mechanism.
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