Electrolytic corrosion in dissimilar metals

[bantam175uk]

We are contemplating using mating connectors plated with Cadmium (aluminium shells) in one connector and Zinc Cobalt plating on the other connector.This is a naval application in salt spray atmosphere. I don't have enough experience to be sure about the corrosive effects of these dissimilar metals. Can any one advise?
Regards.
Bantam175uk

 

[lattar]

If dissimilar metals are in electric contact and there is also electrolyte (in this case salt water) there is great possibility for galvanic corrosion. From galvanic series you can see how which of your metal is more nobel than other. Less noble will corrode. Galvanic series is measured in certain conditions and it is valid only in these conditions. Usually you don't have series available in that condition you need and you have to use what you find. But the question is what is corrosion rate and this depends for example the area ratio of metals, if less noble metal part is much smaller (surface area) then it will corrode quit fast. Also temperature has its own effect usually greater temperature the greater rate. Electrolyte (is it pure water, sea water, salt water, acidic water and so) has also great incluence and this may also even change metals position in galvanic series. You will found information from

http://www.corrosion-doctors.org/Definitions/galvanic-series.htm

I hope this helps