Direct measurement of open circuit potentials as a non-invasive technique for evaluating the degree of corrosion of archaeological objects
Keywords:
técnica electroquímica, metales, arqueología, restauración, corrosiónAbstract
This work presents a new methodology for the analysis of metallic heritage based on the evaluation of the degree of corrosion of metallic objects of archaeological origin, as well as the effectiveness of stabilization and passivation treatments. The technique consists of the direct measurement of the “dry” open circuit potential (OCP) between two points of the object, one of which corresponds to a conducting region. The evolution over time of the OPC shows variations that can be related to the so called metal-semiconductor contact potential, which expresses the potential difference that is established between a metal and a semiconductor when an electrical communication is created between them. Since metallic corrosion products have a semiconducting nature to a greater or lesser extent, these differences in contact potential would determine the variations recorded in the OCP measurements.
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References
A.S.T.M. Standard, C876: Standard Test Method for Corrosion Potentials of Uncoated Reinforcing Steel in Concrete, ASTM International, West Conshohocken, PA, 2009.
Berthomé G., Malki B. y Baroux B. (2006): “Pitting transients analysis of stainless steels at the open circuit potencial”. Corros. Sci., 48: 2432-2441.
Cano E., Crespo A., Lafuente D. y Ramírez-Barat B. (2014): “A novel gel polymer electrolyte cell for insitu application of corrosion electrochemical techniques”. Electrochem. Commun., 41: 16-19.
Cano E., Lafuente D. y Bastidas D.M. (2010): “Use of EIS for the evaluation of the protective properties of coatings for metallic cultural heritage: A review”. J. Solid State Electrochem., 14: 381-391.
Cheng W. y Compton R.G. (2014): “Electrochemical detection of nanoparticles by ‘nano-impact’ methods”. TrAC Trends Anal. Chem., 58: 79-89.
Degrigny C., Guibert G., Ramseyer S. et alii (2010): “Use of Ecorr vs time plots for the qualitative analysis of metallic elements from scientific and technical objects: The SPAMT Test Project”. J. Solid State Electrochem., 14: 425-435.
Dickinson E.J.F., Rees N.V. y Compton R.G. (2012): “Nanoparticle–electrode collision studies: Brownian motion and the timescale of nanoparticle oxidation”. Chem. Phys. Lett., 528: 44-48.
Di Turo F., De Vito C., Coletti F., Mazzei F., Antiocchia R. y Favero G. (2017): “A multi-analytical approach for the validation of a jellified electrolyte: Application to the study of ancient bronze patina”. Microchem. J., 134: 154-163.
Doménech-Carbó, A., Lastras, M., Rodríguez F., Cano E., Piquero-Cilla J. y Osete-Cortina L. (2014): “Monitoring stabilizing procedures of archaeological iron using electrochemical impedance spectroscopy”. J. Solid State Electrochem., 18: 399-409.
Doménech-Carbó A., Peiró-Ronda M.A., Vives-Ferrándiz J., Duffó G.S. y Farina S. (2021): “‘Dry’ electrochemistry: a non-invasive approach to the characterization of archaeological iron objects”. Electrochem. Commun.,125: artic. 106992.
Duffó G.S., Farina S.B. y Soriano C.M. (2009): “Characterization of solid embeddable reference electrodes for corrosion monitoring in reinforced concrete structures”. Electrochim. Acta, 54: 1010-1020.
Neff D., Dillmann P., Descostes M. y Beranger G. (2006): “Corrosion of iron archaeological artefacts in soil: Estimation of the average corrosion rates involving analytical techniques and thermodynamic calculations”, Corros. Sci., 48: 2947-2970.
Ramírez-Barat B. y Cano E. (2015): “The use of agar gelled electrolyte for in situ electrochemical measurements on metallic cultural heritage”. Electrochim. Acta, 182: 751-762.
Rémazeilles C., Neff D., Kergourlay F., Foy E., Conforto E., Guilminot E., Reguer S., Refait P. y Dillmann P. (2009): “Mechanisms of long-term anaerobic corrosion of iron archaeological artefacts in seawater”. Corros. Sci., 51: 2932-2941.
Sassolini A., Colozza N., Papa E., Hermansson K., Cacciotti I. y Arduini F. (2019): “Screen-printed electrode as a cost-effective and miniaturized analytical tool for corrosion monitoring of reinforced concrete”. Electrochem. Commun., 98: 69-72.
Selwyn L. (2004): Overview of archaeological iron: the corrosion problem, key factors affecting treatment, and gaps in current knowledge. Proc. Metal 2004. National Museum of Australia. Canberra: 294-306.
Scholz F., Hellberg D., Harnisch F., Hummel A. y Hasse U. (2004): “Detection of the adhesion events of dispersed single montmorillonite particles at a static mercury drop electrode”. Electrochem. Commun., 6: 929-933.
Venkatraman, Cole I.S. y Emmanuel B. (2011): “Model for corrosion of metals covered with M.S. thin electrolyte layers: Pseudo-steady state diffusion of oxygen”. Corros. Sci., 56: 7171-7179.
Venkatraman M.S., Cole I.S. y Emmanuel B. (2011): “Corrosion under a porous layer: A porous electrode model and its implications for self-repair”. Corros. Sci., 56: 8192-8203.
Vives-Ferrándiz Sánchez, J., Iborra Eres, P., Bonet Rosado, H., Pérez Jordà, G., Carrión Marco, Y., Quesada Sanz, F., Ferrer García, C. y Tortajada Comeche, G. (2015): “Ofrendas para una entrada: un depósito ritual en la Puerta Oeste de la Bastida de les Alcusses (Moixent, Valencia)”. Trabajos de Prehistoria, 72(2): 282-303. <https://doi.org/10.3989/tp.2015.12155>.