Mike, your message is posted below as requested. Hope I got the subject line ok.
For you, and anyone else having sign-off problems, Gayatri (at) [log in to unmask] can
assist. Please communicate with her directly with as much "old" address info as
possible so she can find and remove it. jack
>>> "Barmuta, Mike" <[log in to unmask]> 05/24/99 11:36AM >>>
Jack: This got bounced back because our company has changed our e mail
addresses. Please post and I will try to re-subscribe and unsubscribe.
thanks Mike Barmuta
Kathy: Zinc plating when used as an outer or final finish is usually treated
with a phosphate or chromate coating. Since zinc is an extremely active
metal this helps protect it from the environment. You do not state if you
are using a protective coating on the zinc plate. If you are not, you should
be. If you are using one perhaps these units did not receive it.
Regarding the streaking, based on some of the elements found it could be the
result of hard water.Check with the plater to see what type of water
purification (typically DI) they are using for the final rinse and that it
is operating properly.
It is also possible there is iron contamination in
the zinc plating bath or the plating is thin, have it checked out.
The finger prints are probably etched into the surface of the zinc. Somebody
wasn't wearing their gloves while handling the chassis and the acids on
their fingers etched into. Good Luck.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett Wa.
425-356-6076
-----Original Message-----
From: Kathy Stillings [mailto:[log in to unmask]]
Sent: Friday, May 21, 1999 9:13 AM
To: [log in to unmask]
Subject: [TN] HELP - NEED INFO ON PLATING ISSUE
Hi Everyone,
Was wondering of I could get some input from any Guru on plating issues.
Need info ASAP!!!!!!!!!!!!!!!!!!!! Here's the problem: have a zinc plated
chassis with a base of stainless steel and the handle is brass plated with
nickel. We have finger prints that can't be removed and a wash-like
streaking across the surface of the material. This stuff "oxidizes" just
sitting in a room and transportation overseas only accelerates the process.
Desiccant agents don't even work.
Testing found iron oxidation randomly spaced along some finger print
patterns. Unsuccessful attempts were made to lift the deposits using tape.
Samples were then cut for testing evaluation. SEM/EDS analysis showed
trace elements of zinc, low levels of chrome, oxygen, aluminum, calcuim
chloride, phosphorus, carbon, chlorine, iron, potassium, silicon, and
sulfur. Higher levels of "corrosive" chlorine were found in fingerprint
areas with small definitive locations of very high calcium. Initiation of
the corrosion has been determined to be at the plating.
Is it possible the plating vendor is using a washing agent after plating
that contains the corrosives mentioned above and over time these elements
are leaching out and corroding the plating? Can someone shed some light in
this issue? We've been using the plating for 6 years and this is a new
occurrence.
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