Cr vs. CrAg plating

[djhurayt]

We have the same part offered by two difference vendors. On one vendors part the plated area is plated with 100% Cr per SEM analysis. The SEM on the other parts show the plating to be 95% Cr and 5% Ag.

My question is (with little knowledge of chrome plating) what is the purpose of the addition of silver?

 

[WKTaylor]

Was the Cr+Ag SEM analysis the indication of an 'alloy'... or of 2 discrete layers of plating [for instance, over-plating chromium with silver]?

As far as I'm aware... there are NO Chromium-Silver alloys [aerospace]… any ratio... for many reasons.

Comment.
It is 'possible' that the chromium plating tank was contaminated with silver... which would be gross negligence.

Regards, Wil Taylor

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o We believe to be true what we prefer to be true. [Unknown]
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[djhurayt]

one layer of plating, so it appears to be some type of alloy
contamination ???, always possible but do not know, these are basically off the self items for the diesel fuel injector industry

 

[IRstuff]

Ag corrodes, so unless there are decorative reasons, I can't think of why it would be present, particularly in conjunction with Cr

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[btrueblood]

One fitting manufacturer (rhymes with cage block) puts a silver coating on the threads of the swage/compression fitting nuts to reduce the possibility of galling. It's a separate process, though, not a combined plating.