Characterization of the Stainless Steel Corrosion Kinetic By EIS

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Characterization of the Stainless Steel Corrosion Kinetic By EIS R. Galvan-Martinez1*, M. Flores-Cocuyo1, R. Orozco-Cruz1, A. Contreras2 1 Unidad Anticorrosión, Instituto de Ingeniería, Universidad Veracruzana Av. S.S Juan Pablo II s/n, Z Universitaria, Fracc. Costa Verde, Veracruz, México, CP 94294. * Email: [email protected] 2

Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas Norte 152, San Bartolo Atepehuacan, México. CP 07730

ABSTRACT An electrochemical study was carried out in order to obtain the effects of the turbulent flow condition on the stainless steel corrosion immersed in natural seawater using an electrochemical corrosion technique like electrochemical impedance spectroscopy (EIS). A three-electrode electrochemical glass cell was used to obtain the electrochemical measures, where a cylinder of the AISI 410 stainless steel was used as working electrode, a saturated calomel electrode as reference electrode and a synthesised graphite rod as auxiliary electrode. 24 hours was the total exposure time. In order to control the hydrodynamic conditions a rotating cylinder electrode (RCE) was used and, a scanning electron microscope (SEM) was used in order to obtain the superficial analyses of the metallic surface after tests. The results of the electrochemical techniques shown that at 1000 rpm of the rotation speed, the corrosion rate (CR) increased as the exposure time also increased. In additions, in the other rotations speed (2000, 3000 and 5000 rpm), the CR was affected by the corrosion products formed on metallic surface. t is important to point out that the corrosion morphology found in the steel sample was localized corrosion. Keywords: Corrosion, Film, Steel, Morphology, Passivation. INTRODUCTION A corrosion process can be influenced, in different ways, by the relative movement between the metal and the corroding environment. This relative movement can increase the heat transfer and the mass transfer of reactants towards and from the surface of the corroding metal, with a consequent increase in the corrosion rate. Also, if solid particles are present, removal of protective films, erosion and wear on the metallic surface can occur. The corrosion of the metallic structure under turbulent flow is complex, but this problem has been studied mainly in the oil industry [1-3]. In order to describe the metallic corrosion under this flow conditions, some researchers have carried out different hydrodynamic systems with different degrees of success [4-6]. Some hydrodynamics systems using in the study of the corrosion phenomenon under turbulent flow conditions are: rotating cylinder electrode (RCE), close – circuit loops, submerged impinging jet, concentric pipe segments, etc. It is important to point out that all of them have been used in the metallic corrosion and they have been important in the improvement of the understanding of the corrosion process taking place in turbulent flow conditions [7-11].

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One hydrodynamic systems that acquired popularity and good acceptation in the scientific c