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Characterization of archaeological bronze and evaluation of the benzotriazole efficiency in alkali medium
Author(s) -
Hassairi H.,
Bousselmi L.,
Khosrof S.,
Triki E.
Publication year - 2008
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.200704064
Subject(s) - benzotriazole , bronze , copper , immersion (mathematics) , materials science , corrosion , electrode , polarization (electrochemistry) , alkali metal , electrochemistry , dielectric spectroscopy , metallurgy , chemistry , mathematics , organic chemistry , pure mathematics
An analytic study permits us to characterize the altered surface of an archaeological bronze coin and to determine the structure and the composition of the patina covering the whole surface of this artefact. This patina could be interpreted at first sight as a type I patina, with copper product deposits on it, with some punctual and enlarged localized type II corrosion. To achieve the purpose of this work, we investigate the behaviour of an archaeological bronze in the presence of benzotriazole (BTA) in alkali medium with the intention of getting a better passivity while favouring the formation of a polymeric film on the surface of the working electrode. The behaviour of the considered interface is investigated by electrochemical impedance spectroscopy, in the presence and absence of an oxide layer, according to the immersion time. At pH = 9, in the presence of 15 mmol/l of BTA, the optimum percentage of inhibition efficiency (IE%) is 67% obtained after 30 min of immersion. A pre‐polarization of the bronze working electrode is realized in order to accommodate the preservation technique used in museums and to improve the formation of the Cu(I)‐BTA polymeric film. The use of a pre‐polarized electrode for 30 min at −35 mV/SCE carries an enhancement of the protection versus the non‐polarized electrode. While comparing the result of our investigation with that obtained using the traditional preservation method, we can establish that using a concentration of BTA 15 times lower, important inhibitor efficiencies (%) of 92 and 97.4%, respectively, for 30 min and 96 h of immersion are reached.