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Monitoring pH in corrosion engineering by means of thermally produced iridium oxide electrodes
Author(s) -
Seguí Femenias Y.,
Angst U.,
Elsener B.
Publication year - 2018
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.201709715
Subject(s) - immersion (mathematics) , electrode , iridium , potentiometric titration , corrosion , oxide , materials science , oxygen sensor , chemistry , clark electrode , ph meter , oxygen , inorganic chemistry , chemical engineering , electrolyte , composite material , catalysis , metallurgy , biochemistry , mathematics , organic chemistry , pure mathematics , engineering
A pH sensor to be used in highly alkaline media under continuous long‐term immersion conditions is crucial in various engineering applications. This work develops the production protocol and posterior conditioning of thermally oxidized iridium (IrO x ) electrodes to be used as potentiometric pH sensors embedded in highly alkaline environments such as concrete or cathodically protected steel in soil. The main investigated aspects for the desired applications are the potential‐pH response, its reproducibility, accuracy, and oxygen dependency. The stability during long‐term immersion is also studied in detail. The studied IrO x electrodes responded to pH changes with slopes between −50 and −68 mV/pH unit, even after continuous immersion in alkaline solutions for almost 2 years. Additionally, the electrodes response did not show oxygen dependency. Our results highlight the importance of sufficient conditioning in alkaline media prior to use. When properly produced, conditioned, and pre‐calibrated the electrodes reproducibly permit measuring the pH with a maximum error of 0.5 pH units over a range of at least pH 9–13.5. Preliminary results show that the studied electrodes are promising sensors for monitoring pH changes in concrete.