New non-destructive method for “in situ” monitoring of anticorrosive protection of organic coatings

Description of the technology

Paint coating is one of the most used methods to delay corrosion process in metallic structures. Metal corrosion is the main reason of metallic infrastructure deterioration (bridges, boats, planes…) causing failures in numerous industrial areas. The economic loss due to corrosion is estimated at about 4% of the Gross Domestic Product (GDP) in industrialized countries. Due to the serious consequences of this phenomenon, it is essential to develop effective methods for early detection of coatings failures and establishment of deterioration mechanisms. However nowadays, most of the inspection methods are indirect, destructive and based on deterministic or probabilistic models, which limits the coatings performance assessment in real operating conditions. The Corrosion Engineering and Materials Research Group (ENCOMAT) proposes a solution to this problem with a new device and a direct and non-destructive test based on electrochemical impedance spectroscopy (EIS).

Specifications

The device defines two concentric and nominally identical areas on the surface to be inspected. Those areas are put in contact with the electrolyte used for testing allowing for EIS measurements. The impedance data obtained, three consecutive measurements, are further numerically treated to extract the interfacial electrochemical impedance, which accounts for the ionic current circulation at the metal-coating interface, parallel to the metallic surface.

Main advantages of its use

• The main advantage of the method is the ability of discriminating between the barrier properties of the coating and the adhesive features. The former are reachable by traditional EIS procedures, but the latter is not measurable using currently available electrochemical non-destructive techniques

Applications

• The method can be used for defect identification, condition assessment, corrective maintenance, and new coating systems development.
• It can be of interest for producers or users of organic coatings (chemical and alimentary industries, naval industry, construction, aeronautics…).
• Providers of industrial devices and consultants for quality control of materials can also benefit of the innovation.