plating, anodizing, & finishing Q&As since 1989
"Zinc migration mechanism"
I wish to understand from a chemical point of view, what is the process of zinc migration.
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 [affil link] -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 zinc is already alloyed with copper in the brass. I would use nickel as a barrier.
Falls Township, Pennsylvania
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