Re: [T3] mounted radio...

["Keith Park" <topnotch@nycap.rr.com>]

Interesting!  I guess my criterion for Stainless is will it look shiney
after a winter in the northeast under my car :-)

Keith


> Even real stainless can rust. The different elements in many stainless
alloys
> coexist in crystals of the separated metals. The chromium and nickle
crystals
> form a clear oxide film quickly which prevents further corrosion, but pure
iron
> crystals at the surface will still rust, especially if the part has been
> machined and cut thru some of the pure iron crystals.
>
> Passivation is a process which selectively eats away any exposed iron from
a
> stainless part. It's a common treatment for machined stainless parts which
must
> stand up to adverse weather conditions. Passivation consists of a hot acid
bath
> which the parts are immersed in for a few minutes, and then rinsed off.
>
> As part of a summer job many years ago, I ran a passivation bath for a few
> days. I had no idea at the time what I was doing, and the main thing that
I
> remember about it was that the bath was heated by steam radiators which
were
> also in the tank. The radiators themselves were stainless, but the pipes
> leading to them were just iron, so we had to haul the radiators out about
once
> a shift just to replace the pipes when they started to leak because of
being
> eaten away.
>
> The steamfitter who did the actual pipe replacements made a big impression
on
> me when he explained how stupid it was that the people in charge were too
cheap
> to buy a few feet of stainless pipe, which would have paid for itself in
just a
> couple of days of not having to shut down the bath for an hour every
shift.
>
> -- 
> *******************************
> Jim Adney, jadney@vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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