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Corrosion between electroless nickel and and substrate and/or strike layer

2005

Hello,

I have a question regarding the corrosion behavior of electroless nickel. I have been electrolessly plating small parts to increase their wear resistance as a project. Some of these parts may be used in aqueous environments. The nickel is medium phosphorus and about 25 microns thick. To get the eless nickel to adhere I am using a strike to get some pure nickel on the substrate. My question is, if the electroless nickel cracks from mechanical load (or naturally from poor processing parameters), will there be galvanic corrosion between the electroless nickel and the electroplated stike nickel? Is there any way the electroless layer could form a galvanic couple between the substrate and the coating, even though there is a strike layer in between? I realize the best way to prevent this would be to change parameters to make it not crack, but I do not have the resources or equipment make many large scale changes.

Thanks,

Mathew Henderson
Student - Portland, OR, USA

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From what I could read quickly in Gawrilov's Chemical (Electroless) Nickel Plating ⇦[this on Amazon, ... on AbeBooks affil links] by Gawrilov, Portcullis Press, Redhill, Ni-P coatings are more resistant to galvanic nickel. So cracks will probably cause the underlying nickel to corrode preferentially to the electroless deposit. Also the base metal will probably go first too.

  
Tom Pullizzi
Falls Township, Pennsylvania
2005