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Thomas,
That is very interesting and informative and I
appreciate you quoting it; but nowhere do I see it say that stainless
will deteriorate in a non oxygen environment once it has become passivated.
Still it's information I never had before and I
appreciate that. I must admit however that have I seen evidence of
stainless steel deterioration ( oxidation or rusting) in other than carbon
stainless, or pitting in stainless in extreme environments. The only thing
I've seen it do is go dull over a number of years, perhaps that's
the oxidation process they refer to. If that is the case I don't see a
major problem there.
George ( down under)
Yeah
... I just know what I read.
Here is the explanation I
read:
"The basic resistance of stainless steel occurs because of its
ability to form a protective coating on the metal surface. This coating is a
"passive" film which resists further "oxidation" or rusting. The formation of
this film is instantaneous in an oxidizing atmosphere such as air, water, or
other fluids that contain oxygen. Once the layer has formed, we say that the
metal has become "passivated" and the oxidation or "rusting" rate will slow
down to less than 0.002" per year (0,05 mm. per year).
Unlike aluminum
or silver this passive film is invisible in stainless steel. It's created when
oxygen combines with the chrome in the stainless to form chrome oxide which is
more commonly called "ceramic". This protective oxide or ceramic coating is
common to most corrosion resistant materials."
From: "George Lendich" <lendich@aanet.com.au>
Sent:
Sunday, July 18, 2010 5:17 PM
To: "Rotary motors in aircraft"
<flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: Tie
Down Hardpoints
Thomas,
Well that's a new one on me. Sound to me
you might be getting confused with Anodized Aluminium. I know lower
grade stainless can pit because of electrolysis in extreme environments
and because of that they use 316 ( marine) grade. I know carbon grade
stainless can rust
However if anyone can confirm this I
would appreciate hearing further about it.
George ( down under)
I
think I want to stay away from the stainless because it will be completely
enclosed in fiberglas.
Stainless needs to be exposed to an oxygen
environment in order to for that protective layer (chrome oxide) that
prevents further oxidation.
At least that's what I've been
told/read.
Thomas,
I agree with Tony, use something that won't
rust, nothing looks worse on the exterior of a plane. Maybe consider
stainless steel, I use it on everything.
George (down under)
Hey
Tony.
Now I'm looking for the tie down hardpoints (either parts or
specs) referenced on page 25 of the 'A' kit manual.
I have not
found them in the drawings either.
They say thay are Cad plated
steel. I can have them made but I would be guessing.
Maybe .125
3" x 3.5" plate would suffice with a threaded steel bushing welded to it
and then plated.
I figure the bushing threaded/tapped 1/4" x 28 could
be 5/8" material ... maybe. ... or 3/4".
Any
Ideas?
Thanks.
T Mann
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