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Why is Chrome rusting

Q. What physics would cause the chrome plating to fail allowing rust to occur?

Chris Niehaus
Engineer - Jackson, Michigan
2007

A. Lots of things. poor under coat of nickel, poor processing, layers are not thick enough for the use and used in an environment that it will not stand up to. Just for starters.

James Watts
- Navarre, Florida
2007

A. Probably the biggest cause of poor adhesion is due to poor surface cleanliness or contamination. Other potential causes include mechanical damage and residual stresses causing the coating to crack.

Toby Padfield
Automotive module supplier - Michigan
2007

A. Hi Chris. We have an FAQ, "Introduction to Chrome Plating" which will answer the question in pretty fine detail, but the short answer about the physics is either the nickel & chrome are peeling off as previous responders said or the nickel is too thin and thus it is porous or has pinholes.

In the same way that zinc anodes protect steel ships by preferentially dissolving because zinc is a more active metal than steel,
when steel is chrome plated, the underlying steel will effusively rust through pinholes to protect the nickel & chrome because steel is more active.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
October 2013

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