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New Metal That's Full of Holes
anoopsinha writes "Wired reports: 'Caltech researchers have made a metallic glass-based foam that is stronger than traditional metal alloys, providing industry with a revolutionary lightweight material.' Currently the applications envisioned for metallic foams are in automobile and aircraft crumple zones, which absorb the impact of collisions, and in artificial bone. Some imagine using the foam to create structures in space."
An early adult dream, as opposed to the late childhood dream of an orbiting factory, was to build a woodstove lined with shuttle tiles. The idea was to preheat incoming air and burn with very little heat loss other than deliberate extraction. That would allow the firebox to stay at the right temperature for clean burning, even at low burn rates.
Anyway, shuttle tiles aren't cheap, and it isn't just because they're on the shuttle built to government specifications. Shuttle tile material is expensive to fabricate, and I've heard indications that it's really not a very nice thing to have around. Not quite like asbestos, but in that general direction.
Before picking up a piece of aerogel, I'd like to hear more about its biological properties. I can easily see bits and pieces flaking off and floating through the air, to be inhaled or ingested.
The living have better things to do than to continue hating the dead.
The blurb Timothy posted (or approved and passed on) said: "Currently the applications envisioned for metallic foams are in automobile and aircraft crumple zones, which absorb the impact of collisions..."
This sentence is taken from the article, but refers to the old-style metal foams, which have been tested for decades, NOT the 'glassy' metal foam discussed in the article. Most of the article explains why the new glassy foam is different from the old ones, and lists properties, like rigidity and high elastic energy return, which make it specifically unsuited for use in crumple zones. The article itself says:
"Given the bounce bubbloy would have off a wall or tree, Veazey said it might not be suitable by itself as a crumple zone."
Hitting a wall and bouncing creates up to twice the change in momentum, and potential for damage to humans, as a 'hit and stick impact' (e.g. wrapping your car around a tree or hitting the concrete after a 100 story fall). The impact would admittedly be mitigated by being spread out over several milliseconds vs. nearly instanteous, but "high elastic energy RETURN" is the opposite of an "energy ABSORBING crumple zone".
Similarly, a high rigidity, high energy return, bone replacement would place an extreme stress on its anchors and surrounding real bone. You want a material that absorbs energy as it flexes, rather than returning is as a one-two punch (initial impact and then sharp recoil in the opposite direction) The energy absorbed by the flexing of a good bone substitute should be released as heat (it takes a lot of kinetic energy to make rather little heat) instead of crumpling [mechanical deformation] like a Mercedes front end.
This glassy metallic foam has many potentially interesting applications. It's a shame that the blurb picked up on two applications where the old foams look more promising than the topic of the article
And this is only one of the spectacular things that NASA is doing next year. There is also the Mars rovers mission, Cassini-Huyghens will arive at Saturn, and (hopefully) the Shuttle will fly again..
karma capped
Well, it's made out of silica, so silicosis is a bit of an issue, but it rarely makes it to your lungs because most forms of aerogel suck up liquid like, well, a sponge and any particles the right size to shred lung usually sucks up enough water to keep it from floating into your lungs.
Ingestionwise, I don't know offhand of anyone who's had a problem with it, other than maybe making them thirsty.