September 11, 2007

Give a Yell for Aerogel!

Hatched by Dafydd

Aerogel is one of the weirdest man-made substances on the planet. First, it's the lightest stuff in the world -- literally: An evacuated form of aerogel is a solid, but is actually less dense than air (meaning it would "float" on air).

But it's also an amazing insulator against both cold and heat; it's an excellent dessicant, or drying agent; it can mimic a biological cell, absorb oil, lead, and mercury pollutants... and aerogel armor can even protect against impact from bullet or bomb... or maybe even a car crash.

Scientists produce aerogel by taking a silica gel that is mostly water and slowly replacing all the water with air; the process is called "supercritical drying." The result has been dubbed "frozen smoke" (not to be confused with liquid smoke, which lazy cooks squirt on food to simulate barbecue flavor). Aerogel is mostly harmless, though you should wear gloves to handle it, as it can dry and crack your skin by absorbing all the water from it.

But for me, the most interesting potential use for aerogel is in military armor, both for individual soldiers and for vehicles. For some odd chemical reason, it's extraordinarily resistant to impact. From the Fox News piece above:

Aerogel is also being tested for future bombproof housing and armor for military vehicles. In the laboratory, a metal plate coated in 6 mm (a quarter of an inch) of aerogel was left almost unscathed by a direct dynamite blast.

The quarter-inch of aerogel would mass only a fraction of what a similar volume of current armor masses, allowing equivalent (or even superior) protection with a fraction the weight. Already, soldiers and Marines complain about the sheer weight of the body armor they must wear; it's not uncommon for our fighting men not to wear the "best" armor because it renders them virtually immobile. Anything that decreases the weight will increase the number of soldiers who consent to wear it.

For a graphic demonstration of the difference, let's look at two very short videos (less than ten seconds each). In the first, a high-speed test projectile strikes impact-resistant acrylic glass (PMMA -- Polymethyl methacrylate):

(YouTube here.)

Notice that the glass simply shatters under this impact. But now, let's see a much thinner pane of aerogel under an identical impact:

(YouTube here.)

In this video, the aerogel stretches but does not break, and the projectile does not penetrate.

The same principle applies to vehicles, of course: Combining the light-weight, high-impact-resistant aerogel with the V-shaped bottom of an MRAP vehicle could make devastating IEDs a fading memory.

But another use not generally mentioned is to create a thermal-insulating blanket that can wrap around hot parts of a helicopter or tank -- thus obscuring the target from infrared sensors mounted on missiles:

In particular, their aerogel blanket can be used to radically cut infrared emissions from helicopters, making it much harder for heat-seeking missiles to lock on to them. As reported by Aircraft Survivability magazine [page 38 in the pdf]:

...This program focused on the use and optimization of aerogels as a high performance insulation material, encapsulated in innovative, lightweight packaging. The aerogel blanket insulation system, with a weight of only 5 pounds, demonstrated a 40 percent reduction in aircraft IR signature during flight demonstrations on an Army OH–58D Kiowa.

This is spectacular stuff, all part of a revolution in chemical engineering dating back at least to the 1930s (when aerogel and Bakelite were invented). As I have argued many times, while it's true that our enemies -- al-Qaeda, Iran, the Communists -- adapt to our techniques, we adapt so much more rapidly to theirs, and invent new strategies and tactics out of whole cloth so effortlessly, that I have no fear that we will be overwhelmed by a technology duel... bring it on!

Nobody converts basic science into real-world engineering better than the United States of America; we are a nation of hip nerds.

Hatched by Dafydd on this day, September 11, 2007, at the time of 3:18 AM

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The following hissed in response by: cdquarles


Amen, bro. I can imagine some seriously geeky/nerdy goings on in Area 51 right now involving computer simulated computational chemistry. The major hurdle to aerogel mass production right now is technological. I can also imagine some 180+ IQ engineers working on this at our weapons national labs (the only Constitutional Federal funding of science and engineering, which includes most of the early NASA stuff; not the Dr. Hansen type stuff).

The above hissed in response by: cdquarles [TypeKey Profile Page] at September 11, 2007 10:45 AM

The following hissed in response by: MaidMarion

My nephew works at Aerogel but I never considered him a nerd or geek :)

The above hissed in response by: MaidMarion [TypeKey Profile Page] at September 11, 2007 7:56 PM

The following hissed in response by: RBMN

The thermal insulation of this stuff is fantastic. It's going to save tons of energy that's wasted now on heating, or cooling. Aerogel, and a small geothermal heat pump, is probably all you'll ever need to heat or cool your home.

The above hissed in response by: RBMN [TypeKey Profile Page] at September 11, 2007 10:20 PM

The following hissed in response by: levi from queens

This was a great piece of knowledge. Thank you Mr. and Mrs. Lizard for posting it.

How much energy does it take to create it? I guess even if it's outlandishly high, there will still be a net saving.

The above hissed in response by: levi from queens [TypeKey Profile Page] at September 12, 2007 6:51 AM

The following hissed in response by: Big D

Next up - ferrogel. Turns from liquid to solid in 1/100th of second when an electrical current is applied. Used to make soft, lightweight, flexible armor that goes rigid as steel when a bullet strikes it.

Doesn't Bin Laden realize that each video he sends from his cave just reinforces the message that victory for us is inevitable?

The above hissed in response by: Big D [TypeKey Profile Page] at September 12, 2007 8:52 AM

The following hissed in response by: Hal

I'm a molecular biology grad student, so the only thing that really interested me was the way lipid bilayers will form around this stuff. That could have incredible research potential.

Of course, as far as using the stuff for body armor, I can see one potential drawback. If the stuff is as good an insulator as you say it is, then it might be incredibly uncomfortable to wear in heat of Baghdad. They'd really have to figure out how to keep someone from overheating while wearing a suit that doesn't let heat escape.

The above hissed in response by: Hal [TypeKey Profile Page] at September 12, 2007 9:57 AM

The following hissed in response by: Don

I think you missed a trick, Dafydd. Tank armor is all very fine - but think about car armor! a layer of this applied to car panels could make cars much more resistant to collision damage, eh?

The above hissed in response by: Don [TypeKey Profile Page] at September 12, 2007 11:02 AM

The following hissed in response by: Don

I'll bet they can work out a way to finess the body armor, Hal. Air holes maybe, particularly in areas where bullets are unlikely to impacts - such as the armpits.

Perhaps they could drill aiirholes at the bias to allow air to escape without allowing a direct route for bullets or shrapnel to enter.

The above hissed in response by: Don [TypeKey Profile Page] at September 12, 2007 11:06 AM

The following hissed in response by: Bookworm

We were visiting a relative who works at the Jet Propulsion Lab down in Pasadena, and got a chance to see an aerogel exhibit. It's really quite amazing stuff. At first, we walked by the display with a rather casual attitude, thinking we were looking at a hologram. It was only when one of our group stopped to read the label that we realized we were looking at an awesome substance. After that, we just all sort of hung around the display, trying to understand what a bizarre and wonderful thing was hovering weirdly before our eyes. I'm sorry to say, though, that it never occurred to any of us that it could have such great practical applications here on earth, and not just out in space.

The above hissed in response by: Bookworm [TypeKey Profile Page] at September 15, 2007 12:00 AM

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