Quote:
Originally posted by Althornin
as BB says, you've got it backwards.
The potential created by the mixture of the metals is easily looked up ont he web.
Applying this voltage "opposite" the created voltage will negate any galvanic corrosion, because no effective electron flow will be taking place.
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Seems like a strange usage of the word "opposite" to me, but I suppose it's just a matter of perspective.
In any case, the added voltage source does no good unless there is a reasonably high resistance leakage path. (The resistance shown as a zig zag line in the attached image.)
If the leakage path is not there, then the added voltage source serves no purpose - there is no current flow to stop.
If there is a leakage path but it is 'high' resistance, then the added voltage source can provide the current to maintain the correct voltage across the resistance, and prevent current from flowing through the Galvanic cell.
If there is a leakage path but it is low resistance, then the amount of power required to stop the flow of current through the Galvanic cell is excessive.
Eliminating the leakage path, seems the most practical solution wrt waterblocks. (Assuming protection beyond chemical corrosion inhibitors is desired.)