SEDL / STP / STP1188-EB / STP18083S

Analyzing and Interpreting Electrochemical Impedance Spectroscopy Data from Internally Coated Steel Aerosol Containers

Tait, WS
Research associate and scientist, S. C. Johnson and Son, Racine, WI

Handrich, KA
Research associate and scientist, S. C. Johnson and Son, Racine, WI

Tait, SW
Educational consultant, Tait & Associates, Racine, WI

Martin, JW
Senior materials research engineer, National Institute of Standards and Technology, Gaithersburg, MD

Pages: 10    Published: Jan 1993

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Abstract

Internally coated steel aerosol container corrosion and coating parameters derived from electrochemical impedance spectroscopy (EIS) data can have a range of values, requiring collection of data from multiple samples on a given coated container/ electrolyte system. Multiple specimens enable estimation of distribution curve shape, and thus estimation of the fraction of the entire container population that will experience failure at a given time. Three types of EIS curves, (1) Bode magnitude, (2) Bode phase, and (3) Nyquist, should be used to determine how many responses (time constants) are present in an EIS data set. Capacitances are used to determine what type of process is being observed for each responses. Low Chi-square values lead to the conclusion that more accurate estimates of capacitances are obtained from analysis of individual responses, instead of from analyzing an entire data set with a single equivalent electrical circuit.