Electrochemical behavior of carbon steel in alkaline sour environments measured by electrochemical impedance spectroscopy

EIS characterization of tantalum and niobium oxide films based on a modification of the point defect model

“…The breakdown of oxide films may be promoted by the formation of molecular hydrogen at the metal-film interface, when a critical condition of pressure is reached. Experimental evidence for this phenomenon has been reported in the literature for different electrochemical interfaces [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Chemical Characterization of Corrosion Films Electrochemically Grown on Carbon Steel in Alkaline Sour Environment

“…All these factors are controlled by applied potential and growth time. [1][2][3][4] In a previous work, an electrochemical methodology ͑potentiostatic cyclic pulses͒ was used to obtain corrosion films whose topography depended on the time of carbon steel surface damaging in a concentrated alkaline sour environment ͓1 M (NH 4 ) 2 S, 500 ppm CN Ϫ as NaCN͔. 1 Later, these films were characterized by cyclic voltammetry and electrochemical impedance spectroscopy ͑EIS͒ in an alkaline sour medium simulating the average composition of sour waters of condensates in oil refinery plants ͓0.1 M (NH 4 ) 2 S, 10 ppm CN Ϫ as NaCN͔.…”

“…1 EIS spectra analyses, by equivalent circuit models, have allowed us to establish that the corrosion process at the interface carbon steel/film/sour media exhibits the following stages: oxidation reaction at the metal/film interface, a diffusion process of iron ions from the metal/corrosion products interface through the film, and diffusion of atomic hydrogen (H 0 ) from the electrolyte/corrosion products interface toward the film. 1,2,4,5 This kind of characterization concerns the overall electrochemical behavior of the film ͑bulk and surface͒. However, the surface characterization of the films is an important tool for both developing new corrosion inhibitors and getting more thorough knowledge of the corrosion mechanism and the passivating properties of these films.…”

Corrosion of Mild Steel by Urban River Water

“…[16,17] In the case of alloy 2, the Nyquist plots led to modeling and fitting a different circuit (Figure 3b). [18] The [R(RQ)(RQ)] circuit type from Figure 3a may be correlated with the formation of two layers, one porous and one compact each characterized by polarization resistance values (R 1 and R 2 ) and constant phase elements (Q 1 and Q 2 ), in this case admittance (Y). The non ideality of capacitive elements (replacing capacitors by constant phase elements) occurred as a result of surface roughness, impurities, dislocations, or grain boundaries.…”