Electrochemical Study of Calcareous Deposit Formation in Simulated Soil Solution under Cathodic Protection

Abstract:

Cathodic protection induces the formation of a calcareous layer has been shown to improve metal protection against corrosion by reducing the oxygen diffusion on the metal surface. The present study focuses on the electrochemical scaling induced by the application of cathodic polarisation. A combination of non-invasive in-situ electrochemical techniques and electrochemical impedance spectroscopy was used. Metal/electrolyte interface behaviour was studied using voltammetry to determine the controlling anodic and cathodic reactions. One-week long experiments were conducted. Applied potential –1.2 V_SCE was shown to enable the formation of CaCO₃ allotropes calcite and aragonite, and brucite due to increased interfacial pH which resulted in the formation of hydrogen at the electrode surface. Time constants from bode plots for applied potential –1.2 V_SCE also illustrated the inhomogeneity of the calcareous layer. Modelling of polarisation curves illustrated a “passivation” phenomenon which resulted from formation of hydroxyl cations. This was further validated by bode plots with the added information on the diffusion reaction process. High frequency behaviour showed a steady increase in the electrolyte resistance which may be attributed to the formation of the calcareous layer. Evidence of the initial Mg-gel porous layer, which precedes the formation of brucite, was found.

• Periodical: Key Engineering Materials (Volume 821)
• Pages: 307-312
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.821.307
• Online since: September 2019
• Authors: Phumlani Mjwana*, Philippe Refait, Babatunde A. Obadele, Marc Jeannin, Peter Olubambi
• Keywords: Calcareous Deposit, Cathodic Protection, Voltammetry

References

[1] A. Neville and A. P. Morizot, Calcareous scales formed by cathodic protection - An assessment of characteristics and kinetics,, J. Cryst. Growth, vol. 243, no. 3–4, p.490–502, (2002).

DOI: 10.1016/s0022-0248(02)01532-4

[2] M. Barbalat, L. Lanarde, D. Caron, M. Meyer, J. Vittonato, F. Castillon, S. Fontaine, and P. Refait, Electrochemical study of the corrosion rate of carbon steel in soil: Evolution with time and determination of residual corrosion rates under cathodic protection,, Corros. Sci., vol. 55, p.246–253, (2012).

DOI: 10.1016/j.corsci.2011.10.031

[3] C. Gabrielli, M. Keddam, A. Khalil, R. Rosset, and M. Zidoune, Study of calcium carbonate scales by electrochemical impedance spectroscopy,, Electrochim. Acta, (1997).

DOI: 10.1016/s0013-4686(96)00289-7

[4] H. Karoui, B. Riffault, M. Jeannin, A. Kahoul, O. Gil, M. Ben Amor, and M. M. Tlili, Electrochemical scaling of stainless steel in artificial seawater: Role of experimental conditions on CaCO3and Mg(OH)2formation,, Desalination, vol. 311, p.234–240, (2013).

DOI: 10.1016/j.desal.2012.07.011

[5] C. Barchiche, C. Deslouis, D. Festy, O. Gil, P. Refait, S. Touzain, and B. Tribollet, Characterization of calcareous deposits in artificial seawater by impedance techniques: 3 - Deposit of CaCO3 in the presence of Mg(II),, Electrochim. Acta, vol. 48, no. 12, p.1645–1654, (2003).

DOI: 10.1016/s0013-4686(03)00075-6

[6] C. Deslouis, D. Festy, O. Gil, V. Maillot, S. Touzain, and B. Tribollet, Characterization of calcareous deposits in artificial sea water by impedances techniques: 2-deposit of Mg(OH)2without CaCO3,, Electrochim. Acta, (2000).

DOI: 10.1016/s0013-4686(99)00403-x

[7] Y. Ben Amor, L. Bousselmi, M. C. Bernard, and B. Tribollet, Nucleation-growth process of calcium carbonate electrodeposition in artificial water-Influence of the sulfate ions,, J. Cryst. Growth, vol. 320, no. 1, p.69–77, (2011).

DOI: 10.1016/j.jcrysgro.2011.02.005

[8] P. G. Kossakowski, Prediction of Ductile Fracture for S235JR Steel Using the Stress Modified Critical Strain and Gurson-Tvergaard-Needleman Models,, J. Mater. Civ. Eng., vol. 24, no. 12, p.1492–1500, (2012).

DOI: 10.1061/(asce)mt.1943-5533.0000546

[9] C. Rahal, M. Masmoudi, R. Abdelhedi, R. Sabot, M. Jeannin, M. Bouaziz, and P. Refait, Olive leaf extract as natural corrosion inhibitor for pure copper in 0.5 M NaCl solution: A study by voltammetry around OCP,, J. Electroanal. Chem., vol. 769, p.53–61, (2016).

DOI: 10.1016/j.jelechem.2016.03.010

[10] R. Akkouche, C. Rémazeilles, M. Jeannin, M. Barbalat, R. Sabot, and P. Refait, Electrochimica Acta In fl uence of soil moisture on the corrosion processes of carbon steel in arti fi cial soil : Active area and differential aeration cells,, Electrochim. Acta, vol. 213, p.698–708, (2016).

DOI: 10.1016/j.electacta.2016.07.163

[11] R. Parsons, Atlas of electrochemical equilibria in aqueous solutions,, J. Electroanal. Chem. Interfacial Electrochem., (1967).