HOME FAQs BOOKS JOBS: Help Wanted Suggestions you are here: Hotline/Forum => Letter 11139

Zinc migration mechanism

I wish to understand from a chemical point of view, what is the process of zinc migration.

The product:

CA 260 Brass relay terminal

underplate (2 - 4 micrometre Cu)(78 - 157 microinches)
overplate (2 - 4 micrometre Sn)
No soldering is required on this part, just welding to
another CA 260 Brass metal part.

I have consulted ASTM B545 [link is to spec at TechStreet]-92 which recommends Min 2.5 micrometre Copper or 1.3 micrometre Nickel underplate on metals which contain > 5% zinc to prevent zinc migration. I have received varying recommendations of what underplate of Copper is required to prevent zinc migration. Therefore if I could receive some recommendations and a description of the mechanism or where I can learn more of the process this would be of help to me.

Thank-you very much,

Andrew Ysselmuiden
- OAKVILLE, ON, CANADA

If the ASTM specification calls for copper, I guess that is okay, but it doesn't make much sense to me, since the the zinc is already alloyed with copper in the brass. I would use nickel as a barrier.

Tom Pullizzi
Falls Township, Pennsylvania

ANSWER or FOLLOW UP POST an unrelated QUESTION HOT Topics

Disclaimer: It is not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information
presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The
internet is largely anonymous; some names may be fictitious and some recommendations may be deliberately harmful.

If you are seeking a product or service related to metal finishing, please check these Directories: