AC impedance spectroscopy for evaluating corrosive degradation of coated steel
- Univ. of Nevada, Reno, NV (United States)
Alternating current impedance spectroscopy (ACIS) is commonly used to evaluate the dielectric behavior of electronic materials. This investigation demonstrates that the method is applicable also to measuring the degradation of previously exposed coatings on steel. The method is related to better known electrochemical impedance spectroscopy (EIS) methods but uses simpler, less expensive instrumentation. The results and interpretation are similar for both methods. However, ACIS avoids the need for immersion exposure to an electrolyte during testing. Weathered and otherwise degraded coatings in previous atmospheric exposures can be non-destructively evaluated without additional effects during electrolyte immersion for EIS measurements. In this investigation, previously exposed specimens were sandwiched between foil electrodes, and typical Nyquist and Bode plots were obtained showing progressive losses of coating resistance with exposure time. Good discrimination was found between low and intermediate resistance alkyd and high resistance epoxy coatings.
- OSTI ID:
- 80094
- Report Number(s):
- CONF-940222--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Degradation of epoxy coatings on phosphatized zinc-electroplated steel
Electrochemical noise and impedance analysis of iron in chloride media