Mercury another threat to aviation security?

I just ran across this article and thought it was interesting. It's
reiteration of basic chemistry, but in light of recent history and given
the motivation of some people in the world to hurt large groups of
people traveling at high speed and high altitude in aluminum tubes, the
thought scares me a bit.

http://www.popsci.com/popsci/how2/ar...693558,00.html


Terrorists have so many avenues of attack, I know, but this one seems
like it wouldn't even be on the TSA's radar screens, and a silent but
deadly attack could be unleashed by nothing more than a sufficiently
motivated, mercury wielding criminal. Or would it not be that bad? Is
aluminum destruction through contact with mercury really a potential
threat, or is my imagination running wild? I can't imagine that a
small, discrete amount of mercury could do much damage beyond a small
area, but if it's a critical area, oh boy....

-Aviv


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Full article:

The Amazing Rusting Aluminum

Theodore Gray

Unless you are a representative of a national meteorological bureau
licensed to carry a barometer (and odds are you’re not), bringing
mercury onboard an airplane is strictly forbidden. Why? If it got loose,
it could rust the plane to pieces before it had a chance to land. You
see, airplanes are made of aluminum, and aluminum is highly unstable.

Wait, isn’t one of the great things about aluminum that, unlike iron, it
doesn’t rust? Am I talking about the same aluminum? Yes! Your aluminum
pot is made of a highly reactive chemical. It simply has a trick that
lets it disguise itself as a corrosion-resistant metal.

When iron rusts, it forms iron oxide—a reddish, powdery substance that
quickly flakes off to expose fresh metal, which immediately begins to
rust, and so on until your muffler falls off.

But when aluminum rusts, it forms aluminum oxide, an entirely different
animal. In crystal form, aluminum oxide is called corundum, sapphire or
ruby (depending on the color), and it is among the hardest substances
known. If you wanted to design a strong, scratchproof coating to put on
a metal, few things other than diamond would be better than aluminum oxide.

By rusting, aluminum is forming a protective coating that’s chemically
identical to sapphire—transparent, impervious to air and many chemicals,
and able to protect the surface from further rusting: As soon as a
microscopically thin layer has formed, the rusting stops. (“Anodized”
aluminum has been treated with acid and electricity to force it to grow
an extra-thick layer of rust, because the more you have on the surface,
the stronger and more scratch-resistant it is.)

This invisible barrier forms so quickly that aluminum seems, even in
molten form, to be an inert metal. But this illusion can be shattered
with aluminum’s archenemy, mercury.

Applied to aluminum’s surface, mercury will infiltrate the metal and
disrupt its protective coating, allowing it to “rust” (in the more
destructive sense) continuously by preventing a new layer of oxide from
forming. The aluminum I-beam below rusted half away in a few hours,
something that would have taken an iron beam years.

I’ve heard that during World War II, commandos were sent deep into
German territory to smear mercury paste on aircraft to make them
inexplicably fall apart. Whether the story is true or not, the sabotage
would have worked. The few-micron-thick layer of aluminum oxide is the
only thing holding an airplane together. Think about that the next time
you’re flying. Or maybe it’s better if you don’t.

"Aviv Hod" wrote in message
...
[...] I can't imagine that a small, discrete amount of mercury could do
much damage beyond a small area, but if it's a critical area, oh boy....

Even if the chemical reaction occurred as described (and it sure seems a
little outlandish to me), I think the difficulty in obtaining mercury paste,
along with the difficulty in gaining access to any "critical area" of the
airplane would preclude there being any real threat.

The access to a "critical area" in particular is a major impediment, even
for light GA airplanes, never might transport category aircraft.

Pete

Aviv Hod wrote:
I just ran across this article and thought it was interesting. It's
reiteration of basic chemistry,

Doesn't even need to be metalic mercury...the mercurial salts are bad
enough. I used to have a material sceince professor back in the
seventies that said he was scared to fly because security was always
looking for guns and he knew what held airplanes together and that
a bottle of innocuous looking mercurial salts would kill him. He
used to theorize about pooring it in the lav. The key is that you have
to find some critical piece of EXPOSED aluminum to get it on.