Aluminum alloy in contact with electroplated surface

[55413826481]

Would the contact of Aluminum Alloy 356 T6 and steel treated with zinc-nickel electroplating result in a corrosion problem?
Is the zinc-nickel electroplating a good treatment against corrosion on surfaces exposed outdoor?

 

[EMKWR]

If this is in a humid environment you could have a problem. It depends on the surface ratio of both metals and the corrosivity of the environment. Worst case could be galvanic corrosion of the aluminum compund.

Corrosion-reactions on the zink/nickel surface would be corrected by electrons from the aluminium. Result is corrosion of the aluminium. If there is much more exposed surface of the more noble metal, high corrosion speeds will be the result. Of course this is only possible when there is a full galvanic circle. This will be the case if there is a water-film on the metal surfaces.

To be short, galvanic corrosion can be expected if there is metal/metal contact in a humid and corrosive environment. Do not apply thes near the sea !!!

It can however easily be prevented. A small isolating layer (rubber linin or a polymer coating)would solve the problem.

Zinc-nickel electroplating is a good protection for outdoor applications. The method is widely used on crashbarriers on the highways. Ever seen one of those suffering from heavy corrrosion ?


Edwin Muller
KEMA Power Generation & Sustainables
Arnhem, The Netherlands
E-mail e.f.muller@kema.nl
Internet:

http://www.kema-water.nl