SEDL / STP / STP727-EB / STP28034S

Digital Faradaic Impedance Measurements on Corroding Copper in Acid Solutions

Smyrl, WH
Technical staff member, Sandia Laboratories, Albuquerque, N.M.

Pages: 17    Published: Jan 1981

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Abstract

The faradaic impedance of a rotating copper disk has been investigated in oxygenated acid solutions. The impedance measurement system is based on a digital acquisition and analysis of multiple frequency signals. The frequency range investigated was 0.1 to 500 Hz. In sulfuric acid the corrosion involves the peroxide intermediate whose transport behavior strongly influences the impedance results. Peroxide is not important in hydrochloric acid, but the transport of cuprous ions determines the impedance behavior. Measurements at frequencies higher than about 400 Hz in sulfuric acid show a strong frequency dispersion of the capacitance due to a nonuniform current distribution.