What kind of plating is this?

Just took this wheelnut off:
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You can see the original plating inside, but it's all rusted away on the
outside. The plating looks yellow. I'm curious: does anyone know what
kind of plating it is?
Best wishes,
Chris
Reply to
Christopher Tidy
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Yellow cad?
Reply to
Gerry
I wondered if it was cadmium myself. But I thought cadmium was poisonous. Is it still used? I've recently seen the same colour plating on brand new items.
Best wishes,
Chris
Reply to
Christopher Tidy
Think I just answered my own question. Here's a good article on the subject:
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Looks like it's probably zinc dichromate.
Best wishes,
Chris
Reply to
Christopher Tidy
The irridite finish can also be applied to zinc plating as I recall. Cadmium has fallen out of favor, although it is likely still used for defense purposes.
Harold
Reply to
Harold and Susan Vordos
Can somebody explain this bolt, which is from the above link about coatings?
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Reply to
Cydrome Leader
Those look *like* threads but I don't think they *are* threads.
Dave
Reply to
spamTHISbrp
I read a lot of requirements specifications these days and Cadmium is on the prohibited materials list. But you can get permission to use just about anything if you convince the procurement office it is in the best interest of the military.
Carl Boyd
Reply to
Carl Boyd
Phosphate coatings often are yellow, and they can be (and often are) applied on top of plating.
-- Ed Huntress
Reply to
Ed Huntress
Those look *like* threads but I don't think they *are* threads.
They are threads, but I'd guess they're not of any practical use. At a glance, I would say it's a cylinder head stretch bolt, and the 'threads' are possibly added to modify the stretch properties of the bolt.
Reply to
moray
Here are a couple more interesting links I found:
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Chris
Reply to
Christopher Tidy
Right. Zinc plating affords good rust protection, but it is very vulnerable to even mild acids like fingerprints and acid rain. A dunk in the chromate give the zinc better resistance to mild acids.
Reply to
Don Foreman

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