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Conference Papers Year : 2018

Electrochemical impedance spectroscopy of iron corrosion in H2S solutions


Corrosion of iron exposed to H2S saturated solution at pH 4 was studied by electrochemical impedance spectroscopy, weight loss coupons and surface analysis. Hydrogen permeation was also used as indirect means of evaluating the intensity of the proton reduction reaction leading to hydrogen entry into the metal. Since corrosion in this type of test solution results in the rapid build-up of a conductive and highly porous iron sulfide scale, an impedance model based on the porous electrode was used. This model was well adapted to describe impedance diagrams measured at various exposure times, up to 620 hours and explains the huge value of the double layer capacitance. The pore size distribution introduced a mixed behavior, a part of the porous electrode behaves like a plane electrode and another part corresponds to a porous electrode with impedance proportional to the square root of interfacial impedance. The faradic impedance corresponds to the anodic behavior and is based on the model given by Ma [1,2]. Charge transfer resistance determined from impedance analysis allowed calculating the evolution with time of the corrosion current density. A very good correlation was found between this corrosion current density and the hydrogen permeation current density. As expected in our experimental conditions, permeation efficiency close to 100 % is demonstrated. In addition, weight-loss measurements of the corrosion rate also confirmed the validity of the impedance analysis, with respectively 490 µm/year and 530 µm/year. [1] H. Ma, X. Chen, G. Li, S. Chen, Z. Quan, S. Zhao, L. Niu, Corros. Sci. 42 (2000) 1669–1683. [2] H.Y. Ma, X.L. Cheng, S.H. Chen, G.Q. Li, X. Chen, S.B. Lei, H.Q. Yang, Corrosion 54 (1998) 634–640.
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hal-03978197 , version 1 (08-02-2023)


  • HAL Id : hal-03978197 , version 1


M.D. Deffo-Ayagou, Christophe Mendibide, Claude Duret-Thual, J. Kittel, Nicolas Ferrando, et al.. Electrochemical impedance spectroscopy of iron corrosion in H2S solutions. 12th EMCR 2018, Jul 2018, Cambridge (GB), United Kingdom. ⟨hal-03978197⟩
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