Abstract
Electrochemical impedance spectra (EIS) of six coating systems in 3.5% NaCl solution were measured and the relations between coating resistances and phase angles at different frequencies were analyzed. The results indicated that in middle frequency range, the phase angle and the coating resistance show similar decreasing tendencies. For the coating systems studied, the variation of phase angles at 10 Hz with immersion time was very close to the variation of coating resistance, hence may qualitatively reflect the coating performance. For the studied coating systems, the phase angle at 10 Hz decreased continuously from the beginning, indicating the permeation of the coating system by the electrolytes. When the phase angle reached a relatively stable stage, for different coating systems which was below 40°–20°, meaning the coating has been permeated through and electrochemical reactions under the coatings occurred. In addition, the phase angle at 15 kHz may reflect the state of coating in later stage. These phase angle parameters may be used as quick measurements to evaluate coating performance.
Highlights
The dielectric parameters have been measured in the frequency range 40 Hz–100 MHz and the results indicated that εr, its variation between low and high frequency as well as the loss factor, all increase with frying time and are useful parameters to estimate oil degradation with frying time and conditions
Samples with moisture between 0.2 and 1 g were tested and the best results were achieved at high frequency (10 kHz): the agreement between the moisture estimated with the proposed method and that obtained with the reference technique was very good at high moisture level (2 % error) but it was much worse in the lower moisture range (35 % error)
The response to an electrical stimulus applied to the sample under test in a wide range of frequencies provides an electrical fingerprint of the investigated material and can be used to estimate useful parameters
Summary
Electrical impedance spectroscopy (EIS) is a powerful technique (Barsoukov and Macdonald, 2005) that can be used in a broad range of applications, such as microbiological analysis (Ramirez et al, 2008), food products screening (Grossi et al, 2011a, 2014a), corrosion monitoring (Zhu et al, 2016), quality control of coatings (Amirudin and Thieny, 1995) and cement paste (Christensen et al, 1994), characterization of solid electrolytes (Rafiuddin, 2016) and human body analysis (Clemente et al, 2013). Most EIS investigations are carried out using dedicated lab instruments (frequency response analyzers and LCR meters) featuring high accuracy, a wide range of test frequencies, the possibility to make measurements with a two-, three- or four-electrode configuration in both potentiostat and galvanostat operation mode These instruments normally feature proprietary software for data analysis. The design of embedded portable systems for EIS measurements has become even simpler with the introduction on the market of the integrated circuit AD5933 by Analog Devices, a low-cost impedance analyzer system on chip This device, featuring an on-board test voltage generator (maximum frequency 100 kHz) and a 12-bit 1 MSPS ADC for signals acquisition, can measure impedances in the range 1 k –10 M (extendable to 100 –10 M with an additional circuit).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
