Separated activation and passivation zones on anode protected storage tanks in paper industry

Due to the high conductivity of the white liquid, there is some speculation about the application of anodic protection. It is said that if most of the surface of the anodic protection device is passivated, then some of the activated areas will be passivated due to current polarization. This forced bistable scheme can promote the coexistence of stable passive and active regions, that is, multiple intersections. The results show that the passivation zone and the activation zone exist simultaneously, and the corrosion rate is lower, and the corrosion rate is slightly higher than that of the open circuit. This working state is far from optimal, but it is not the most unfavorable situation.

If the area of the active area expands and grows, the voltage control power supply will provide more current in response to a lower reference voltage. However, the ohmic voltage drop at the reference electrode increases the measured potential. This hides the evidence that the active region exists, so the current output from the power supply is not enough to passivate the active region. When there is not enough passivation current density, the small activation region will expand and increase, so the power supply will produce larger output current in the activation region.

Finally, a balance is maintained between the size of the active region and the incoming and outgoing currents. The area produced is very small, which is lower than the peak current density of carbon steel / pulp system, resulting in high local corrosion rate. As long as the possibility of coexistence of active and passive regions is determined, the above working mode of anodic protection system can be easily corrected. Because of its low resistance to the reference electrode, the potential of the active region is very prominent, so the active region can be easily detected. If an active region is detected, the active region is easily passivated; if the active region is small, it can be passivated again.

Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing cathodic protection technology, engineering design, installation and technical services. 

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