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Effects of DC Current on Galvanic Corrosion

 

I found the severe galvanic corrosion on some automotive fuses after long term humidity exposure. The fuse element is cut out from the Nickel and Silver plated Zinc plate. The Zinc is directly exposed in the air around the cutting surface. The exposed Zinc surface becomes the anode and corroded. During the evaluation, the fuses are supplied with DC currents for 30 min every hour. My question is how does the DC electric current in the circuit effect the galvanic corrosion? At the input side of the fuse, the application current flows from the Silver/Nickel layers to Zinc. At the output side, the current flows from Zinc to the Nickel/Silver layers. Will the voltage drop caused by the application current compensate the galvanic potential on one side and make it worse at the opposite side? Should I see the corrosion on one side be severer than the other side? Will AC current have any impact on the galvanic corrosion? It is greatly appreciated if any one will help me with my questions or hint me some reading materials.

Best Regards,

Yi Wang
- Troy, Michigan

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If you send us a photo of the failure, it would be interesting and instructive. Does one side of the fuse have all the corrosion, while the other side acts as the cathode?

  
Tom Pullizzi
Falls Township, Pennsylvania
 

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I don't think the flow through the circuit should have any effect on galvanic corrosion. Whether the fuses are in use or are in storage, if zinc is exposed and there is enough water vapor to support a galvanic current, the zinc will galvanically corrode.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey