The impedance-based screening of raw materials has a tremendous positive impact in an industry where the state of the oxide film on stainless steel strongly influences process and product performance. This application was made possible by the significant progress made in the understanding of impedance data obtained on stainless steels. Huang et al. [1,2] have demonstrated that, for a disk electrode, frequency dispersion can be avoided by reducing the size of the electrode. Alexander et al. [3] have shown that frequency dispersion associated with specific geometries or distributions can be correlated by use of a characteristic dimension. The frequency at which the impedance response is corrupted by time-constant dispersion is inversely related to the characteristic dimension. This work facilitates selection of proper electrode design.

Even at frequencies below that at which specific geometries or distributions cause distortions to the impedance response, constant-phase-element (CPE) behavior can be seen which is attributed to properties of oxides on steel. Hirshorn et al. [4,5] have identified an approach through which CPE parameters may be interpreted in terms of oxide film thickness and dielectric constant. Orazem et al. [6] described application to different types of steel and to human skin. Riemer and Orazem [7] have described how this improved understanding of the origin of frequency dispersion has given rise to industrial application of impedance spectroscopy to provide rapid, inexpensive, and accurate measurement of the oxide film thickness.

Understanding what parts of the impedance spectra are truly useful requires an inherent understanding of the fundamental mathematics, and leads to the ability to make accurate and rapid measurements of oxide film thickness by EIS. Riemer and Orazem [7] stated that “This ability is invaluable from a manufacturing perspective as it serves as a method to screen the incoming raw material, as well as the product in-between different steps in the manufacturing process, allowing for greatly enhanced quality control.”

References

1. V. Huang, V. Vivier, M. E. Orazem, N. Pébère, and B. Tribollet, Journal of The Electrochemical Society, 154 (2007), C81-C88.
2. V. Huang, V. Vivier, M. E. Orazem, I. Frateur, and B. Tribollet, Journal of The Electrochemical Society, 154 (2007), C89-C98.
3. C. L. Alexander, B. Tribollet, and M. E. Orazem, Electrochimica Acta, 201 (2016), 374-379.
4. B. Hirschorn, M. E. Orazem, B. Tribollet, V. Vivier, I. Frateur, and M. Musiani, Journal of The Electrochemical Society, 157 (2010) C452-C457.
5. B. Hirschorn, M. E. Orazem, B. Tribollet, V. Vivier, I. Frateur, and M. Musiani, Journal of The Electrochemical Society, 157 (2010) C458-C463.
6. M. E. Orazem, B. Tribollet, V. Vivier, S. Marcelin, N. Pébère, A. L. Bunge, E. A. White, D. P. Riemer, I. Frateur, and M. Musiani, Journal of The Electrochemical Society, 160 (2013), C215-C225.
7. D. P. Riemer and M. E. Orazem, The Electrochemical Society Interface, Fall 2014, 23:3 (2014), 63-67.