Impedance analysis on growth of fractal pore structures of ant-nest corrosion on copper

Pitting corrosion with fractal porous structure often occurs on copper tubes used in heat exchangers of air-conditioning equipment, and this corrosion is called an ant-nest corrosion. Galvanostatic controlled EIS (G-EIS) was used to measure 3-dimensianal (3D) impedance during the formation of ant-ne...

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Bibliographic Details
Published in:Electrochimica acta 2024-03, Vol.479, p.143873, Article 143873
Main Authors: Itagaki, Masayuki, Makita, Aoi, Watanabea, Hikari, Shitanda, Isao, Hosogi, Tetsuro, Ito, Shinichi
Format: Article
Language:English
Subjects:
3D impedance
ant-nest corrosion
Copper
G-EIS
transmission line model
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Summary:Pitting corrosion with fractal porous structure often occurs on copper tubes used in heat exchangers of air-conditioning equipment, and this corrosion is called an ant-nest corrosion. Galvanostatic controlled EIS (G-EIS) was used to measure 3-dimensianal (3D) impedance during the formation of ant-nest corrosion on phosphorus deoxidized copper (pd-Cu). Instantaneous impedance at an arbitrary time after galvanostatic polarization was determined from the 3D impedance. The transmission line model (TLM) for fractal porous electrode was applied to detect a branched pore formation on pd-Cu electrode. Nyquist plot of instantaneous impedance at initial stage of ant-nest corrosion shows capacitive behavior and straight line of 45° angle against real axis in high frequency region, indicating that a porous structure was formed at the initial stage. The angle of straight line was varied from 45° to 22.5 and 11.25°, indicating the formation of branched and doble-branched porous structures, respectively.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2024.143873