Quote:
Originally posted by Althornin
i dont understand your use of "leakage path"
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By "leakage path" I mean an electrically conductive connection between the two metals. In the case where the two electrodes are in contact, that path is the connection point(s) of the electrodes. Otherwise, something else, like steel screws, or a smear of AS could provide a leakage path.
Quote:
Originally posted by Althornin
Best way to prevent galvanic corrosion is to simply electrically isolate the two metals... ...Or, as i stated earlier, you can apply the potential voltage in reverse.
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But, if the top and bottom of your waterblock are aluminum and copper, and they are bolted together using threads in the aluminum, then the electrical resistance between them is likely to be on the order of 0.001 Ohms or less.
Off the top of my head, I'll say the desired voltage differential between the copper and aluminum is 2V. Maintaining 2V across a 0.001 Ohm requires 2000 Amps. So doing this would require dissipating 4 KW in the joint between the copper and the aluminum. Kind of makes corrosion a moot point.
Electrically isolating the metals is the only 'good' solution. (Coolant chemistry aside.) I don't think I'm saying anything substantially different than you, just pointing out practicality issues.
BTW, aluminum is more electronegative than zinc. You'd need to go to magnesium as your sacrificial anode.