Re: 1teraflops cell processor possible?

Nick Maclaren <[EMAIL PROTECTED]> wrote:
>del cecchi <[EMAIL PROTECTED]> wrote:
>>> >Also, if you know an aluminium object is going to be immersed in salt
>>> >water, why doesn't a layer of waterproof paint solve the problem?
>>>
>>> It chips and cracks in use, especially near moving parts.
>>
>>It apparently depends greatly on the aluminum alloy that is used.  Many
>>aluminum boats are used in salt water.  They are not anodized.  Neither
>>are the aluminum masts.  The problem with airplanes is that they were
>>not designed for nor tested to withstand salt water immersion.  And it
>>is probably really hard to wash the salt off to make sure nothing bad
>>happens 10 years down the road.
>
>Maybe I am a bit out of date then, but you are certainly correct about
>the issues.  However, I am not totally convinced about the resistance
>of any aluminium alloy to 25 years of exposure to sea water, especially
>when in contact with other metals.

My parents own a 25-ish year old aluminum outboard boat,
which other than having been designed for calm lakes and used
in rough salt water most of its life, has held up ok.
And as others have pointed out, it is used in ships
and in yacht hulls to some extent.

Marine-friendly aluminum alloys form a hard aluminum oxide
layer which resists further pitting or corrosion, on contact
with salt water or salty air.

But they don't to terribly well with salt or salt water in
narrow crevices, in a lot of cases.  And as has been pointed
out in other posts, using different materials with differing
cathodic/anodic galvanic potentials will rapidly corrode out
the anodes.

The key problems with aircraft which get immersed are;
1) Most aircraft structures are thin sheets and stiffeners
which are riveted together, and the whole inside of the
contact areas between sheets and stiffeners and such will
absorb some water and may corrode out from the inside of
those joints.
2) Some aircraft structural alloys do very poorly in contact
with salt water, as opposed to the marine grade and more
general purpose alloys.

One might posit that you could go in and drill out every
single rivet in the structure, completely dissassembling it,
and then clean and reassemble the structure and reuse it.
But that will cost as much as a new airframe.

And all the systems: all the wiring, the engines, the
interiors, etc, those all are going to need to be junked
anyways, because some of them react even worse to the
saltwater than aircraft structures do.

Easier to just write it off and junk it.  The salvage value
of most of the components is zero, and the rehabilitation
efforts are extreme...


-george william herbert
[EMAIL PROTECTED]