Internal Current Effects on Localized Corrosion Rate Measurements Using Coupled Multielectrode Array Sensors

Coupled multielectrode array sensors (CMAS) have been used for real-time monitoring of corrosion, particularly localized corrosion. The internal anodic current on the most anodic electrode in a CMAS was evaluated for aluminum and carbon steel in simulated seawater and dilute hydrochloric acid (HCl) solutions. The Tafel extrapolation method was used to estimate the internal current on the most anodic electrode and the average corrosion current for all electrodes. It was demonstrated that if a metal corrodes dominantly in the form of localized corrosion or uneven general corrosion, the CMAS effectively measures the localized or uneven general corrosion rate. However, if the metal corrodes dominantly in the form of uniform corrosion, the CMAS only measures the uneven portion of the corrosion current.