Effect of the Seawater Flow Velocity on the Protectiveness of Calcareous Deposits by Electrochemical Methods

摘要

The influence of flow velocity on the protectiveness of calcareous deposits which formed by cathodic protection in seawater was studied. The deposition process and the protectiveness of calcareous deposits were investigated by electrochemical impedance spectrum (EIS) and linear polarization resistance technique (LPR). The EIS results showed that the capacitive loops sizes decreased with increasing flow velocities, indicating that calcareous deposits formed at higher flow velocities provided poorer protectiveness. An exponential decrease of protectiveness with increasing flow velocities was observed, which was quantified by LPR. The results of SEM and XRD showed that aragonite of calcium carbonate deposited at lower flow velocities but magnesium hydroxide deposited at higher velocities.