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Rust formation on plated parts
Q. We manufacture speakers, and the outer frames & metal parts are zinc plated & passivated with yellow passivation.
What happens is after storing for a period of one to six months we find formation of rust. Plating thickness is 5 micron. Can any one suggest why this is happening and how we can prevent rust?
- Chennai, tamilNadu, India
2000
A. Two quick possibilities, Mr. Janadanan:
1. Plating shops are very corrosive atmospheres, being extremely humid as they are, and with so much acid mist (designed to strip zinc) about. If you are storing the parts in a plating shop, I'm not surprised that they are rusting.
2. The parts have to be dry . . . absolutely dry, or they will rust in storage.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2000
A. Aside from the "rust happens" truism, the plating thickness could be increased to give somewhat longer protection. Ten microns would be o.k.
Megan Pellenz
- Syracuse, New York
2000
Q. How rust is formed on plated components, i.e., parts plated with zinc nickel trivalent black passivation
V.Swamy Nathan- Chennai, Tamil Nadu, South India
September 15, 2013
A. Hi Swamy. I think we'd need a paragraph or two of details to be able to address your question. Short of that, Megan's "Rust happens" is applicable, i.e., there is rustable steel underneath the zinc-nickel plating.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
September 17, 2013
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