I'm no expert in chemistry, but I know that corrosion can cause great problems in systems. I'm working on a prototype, and trying to figure out if corrosion will cause issues.

The setup
Imagine the following system. Two aluminium rods make contact with thin aluminium plates (3 mm thickness). Each aluminium plate is connected to the battery with copper wires:

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The surface of contact between the aluminium rods and plates is subject to moist and dust infiltration (see figure above). Also the connections from the copper wires to the aluminium plates are in that "dirty zone".
When contact is made, a DC current of 10 Amp flows:

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The contact surface between aluminium rods and plates is about 3 to 4 cm^2. The contact force is about 2 to 3 kg. Contact is not made in a very smooth way. Some gliding or even scratching can occur.

Possible issues
I'm afraid corrosion will appear on the contact surface between the aluminium rods and plates. I'm also worried about the copper to aluminium connections.

Possible solutions

  • Perhaps I should replace all aluminium in the system by copper. Copper is a more "noble" metal compared to aluminium. But copper lacks the same protective natural oxide coating like aluminium has.

  • Perhaps I should insert a "sacrificial metal" somewhere in the system. But I have no idea where to put it in this specific case.

  • Perhaps I have to put some sort of coating on the metallic parts. But I have no idea what coating would be best, and if it can withstand scratching and gliding when the rods make contact to the plates - in a rough way.

  • Perhaps I have to switch from DC to AC current. This would be a last-resort option. For reasons I won't explain here (because it would lead us too far off-subject), this solution would cause an economical issue.

  • $\begingroup$ Unless all air and water is excluded, I'd suggest using another metal than aluminum, not only because of likely electrolytic corrosion, but because a build-up of aluminum oxide on the surface would likely make current flow erratic, or even stop it entirely. $\endgroup$ – DrMoishe Pippik Jun 30 '17 at 22:21
  • $\begingroup$ Thank you @DrMoishePippik . Which material would you suggest? $\endgroup$ – K.Mulier Jun 30 '17 at 22:30
  • $\begingroup$ Your suggested use of copper sounds good. depending on the actual application. Though bronze or brass is stronger, it suffers corrosion at the grain boundaries. Another choice might be stainless steel or monel metal (en.wikipedia.org/wiki/Monel), again depending on the environment. $\endgroup$ – DrMoishe Pippik Jun 30 '17 at 22:45
  • $\begingroup$ Thank you @DrMoishePippik , Monel seems a very interesting option. Would the copper wire connections to the Monel be a spot where corrosion occurs? $\endgroup$ – K.Mulier Jun 30 '17 at 23:00
  • $\begingroup$ Yes, if not thoroughly protected, e.g. by a tightly-adhering varnish. $\endgroup$ – DrMoishe Pippik Jul 2 '17 at 1:52

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