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Chrome/Nickel plating corrosion relationship

2003

I am trying to understand the relationship between Nickel/Chrome plating and corrosion resistance. I have been involved with CRS steel products where small amounts of the Chrome have been removed exposing the Nickel, but retain the Nickel, and can pass the ASTM standard 120 hour fog test, B537-70. Now as the ASTM standard is changing to a 48-hour salt fog I can no longer pass the test. People have told me that this is a "replacement" and equivalent to the water fog, which I disagree with. The problem is, why in the area with the absence of Chrome is the corrosion dramatically increased if Nickel is the corrosion resistant material? The Nickel is .0005 in. thick and the Chrome is .00005 in.

Any suggestions as to corrosion resistant improvements will be appreciated.

Barry Buchanan
research & development - Mooresville, North Carolina

Try a duplex nickel plating half semi bright followed by bight nickel. The chrome plating on top will increase the corrosion resistance.

Todd Osmolski
- Charlotte, North Carolina, USA
2003

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Where chrome is present it imparts a sacrificial protection to nickel (i.e. it corrodes preferentially leaving no visible residue), otherwise nickel develops a green superficial tarnish, which eventually causes a penetration to the base steel.

G. Marrufo-Mexico

Guillermo Marrufo
Monterrey, NL, Mexico
2003

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October 16, 2008

Our FAQ, "Introduction to Chrome Plating" explains the concept of duplex nickel plating and the symbiotic relationship between the nickel and the chrome. Good luck.

Regards,

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