Phil: It depends on what you are using the coating for. Class 1A, Class
III, painted, unpainted, environmental exposure, type of alloy, etc.
We have looked at both MacDermid's NCP and Sanchem's Safegard CC
hexavalent chromate conversion replacements.
We are using them as an unpainted class III finish for electrical
contact NOT as a class 1A. These will be in a fairly benign environment.
We are in the process of doing electrical and environmental testing but
not salt spray/fog.
My gut feel is they may not protect as well as a class 1A hexavalent
chrome finish when scratched i.e. no self healing properties. I believe
there is also an issue with high copper aluminum alloys and salt
spray/fog resistance.
Yes, we have also seen issues with fingerprinting.
Regards
Michael Barmuta
Staff Engineer
Fluke Corp.
Everett WA
425-446-6076
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
Sent: Thursday, March 02, 2006 7:47 AM
To: [log in to unmask]
Subject: [TN] "chrome" conversion of aluminum chassis
Good morning all,
As we move forward with RoHS and in an attempt to comply we are changing
the surface treatment of all our metal chassis parts.
Hexavalent Chrome Alodine or Iridite conversion processes are being
replaced with either a Trivalent Chrome Process (TCP) or Non Chrome
Process (NCP) for surface treatment of aluminum (aluminium for the Brits
out there).
What good, bad or ugly tales do you have? I know fingerprints are an
issue with some platings.
Has anyone changed processes and run salt spray tests? What were the
results?
I'm trying to put together some supporting (or refuting) data on
possible chemistries for conversion coatings to be able to defend our
change decisions.
Thanks in advance,
Phil Nutting
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