Impedance sensor for the early failure diagnosis of organic coatings
A miniature impedance sensor used for field diagnosis of the early failure of coatings has been developed based on microelectronics and electrochemical impedance spectroscopy (EIS).
The aging process of polyurethane-based coatings in salt spray test chamber was studied using the impedance sensor. Several critical indexes related to EIS such as phase angle (θ10Hz, θ15kHz), breakpoint frequency (fb), specific capacitance (C10Hz, C15kHz), and impedance modulus (Z0.1Hz) were proposed to evaluate the severity of coating degradation.
Accurate monitoring of the degradation process
The results indicated that the impedance sensor could accurately monitor the degradation process of coatings, and once Z0.1Hz 106 Ω cm2, fb 100 Hz, or θ10Hz 20°, the coating may be regarded as completely degraded and fails to protect the metal substrate.
The study is published in: Journal of Coatings Technology and Research November 2018, Volume 15, Issue 6, pp 1259–1272.
