48479

Compatibility of stainless steel with zinc nickel plating [Canada] 

April 10, 2008

I have a rivet with zinc nickel plating, and spring with stainless steel material.
If these two components are attached together, will there be any free electron between the two, and have red rust faster ?

Thanks.

Fred Lajewardi
engineering - Canada

Hi, Fred. Galvanic corrosion is always an issue when different materials are connected together. The severity depends on the exposure (if it's dry, little problem; if it's wet, serious problem; if it's salty and wet, major problem); the potential difference between the metals (zinc nickel plating is a sacrifical plating and thus quite active); and the relative sizes (a small active component connected to a larger less active component is trouble). Unless this is a well protected component, indoors, in an electronics device, it sounds like trouble to me.

Regards,

Ted Mooney, P.E.  finishing.com Brick, New Jersey

Ted is absolutely right. If you want to minimise the risk of corrosion, use parts made form similar metals, or put an insulator (eg plastic gasket or washer) between them. This will minimise the chance of any galvanic couple forming.

Trevor Crichton R&D practical scientist - UK