In situ monitoring of a Mg-rich primer beneath a topcoat exposed to Prohesion conditions

Mg-rich primers have been proven to be an adequate alternative for chromate-based coatings for the protection of aluminum alloys from corrosion. The performance of a Mg-rich primer on aluminum 2024-T3 under Prohesion® exposure (ASTM G85) has been monitored using an embedded sensor placed at the surface of the primer and below the topcoat.Electrochemical impedance spectroscopy and noise measurements were conducted to monitor the electrochemical properties of the system beneath the topcoat. The data analysis demonstrates that the sensor is able to detect change in the barrier properties of the topcoat in response to the exposure conditions.