Aerographite: six times lighter than air, conductive, and super-strong

http://www.extremetech.com/extreme/133056-aerographite-six-times-lighter-than-air-conductive-and-super-strong

by razzaj • 14 years ago

95 35 14 years ago

extremetech.com

StavrosK2• 14 years ago

How many times less dense than air is helium?

regularfry• 14 years ago

http://www.wolframalpha.com/input/?i=density+of+air+divided+...

StavrosK2• 14 years ago

Very nice, thank you.

dllthomas• 14 years ago

7.145

wtvanhest• 14 years ago

For those that have studied physics in depth:

The article says: "5,000 times less dense than water, and six times lighter than air"… so what does it mean by lighter than air exactly? I presume in means that if it were in a vacuum that it would have less mass than whatever its outside edges of volume would be?

That seems misleading since if you break the material down to the smallest piece, then compared air volume to that piece it wouldn't actually be lighter right?

Am I thinking about this correctly?

adrianN• 14 years ago

What's the smallest piece? A carbon atom? The only reasonable way to compare densities is to take a sizeable chuck of the material and compare it to the same volume of a different material.

jws2• 14 years ago

We've been down this road before. I think the misleading part is that it doesn't displace air to any significant extent.

By this logic, a roll of chain link fence is three times lighter than water[1]. But it still sinks.

EOM

[1] Calculations follow…

50 feet of 6 foot tall 9 gauge chain link fence rolls into an 18" diameter cylinder 6 feet tall and weighs 216 pounds. http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDi...

Mr. A. Wolfram says that is a volume a 80 gallons. http://www.wolframalpha.com/input/?i=volume+of+a+cylinder+18...

Water is about 8 pounds to the gallon, so the water of equivalent volume would be 640 pounds.

Steel fencing is one third the density of water! Write the press release!

Sorry about the units, world, at least I didn't break into microfortnights.

jopt• 14 years ago

Great analogy, helped me understand why I felt this whole six times lighter thing was strange.

smoyer• 14 years ago

If you break it down to the smallest piece, you're talking about Carbon atoms with an atomic mass of roughly 12 versus (mostly) Nitrogen and Oxygen with approximate masses of 14 and 16. So it's lighter as atoms but not by six times.

Most of the Oxygen in our atmosphere is O2, so there's a bond and space between the atoms as well as space between the molecules and others. In the same way, perhaps the carbon is more like closed cell foam that has voids that exclude other atoms. These voids have no mass but contribute to the effective volume.

alexchamberlain• 14 years ago

Can I ask a stupid question... If it's lighter than air, does it float?

jstalin• 14 years ago

That was my initial thought. If it's lighter than air, it must float...

jws2• 14 years ago

It does not displace a significant volume of air, so no steampunk airships for you. But I'll bet breezes blow it around.

windsurfer• 14 years ago

I wonder if you could wrap the sponge in a balloon-like thing and then take away all the air inside. That would likely float, if the material was strong enough, no?

Stratoscope2• 14 years ago

> six times lighter than air

If it's lighter than air, doesn't it float away? Wouldn't this make it a bit hard to work with? Why doesn't the article say anything about this obvious consideration?

OTOH, the piece in the photo with the drop of water does not appear to be trying to float away - unless it's the water drop holding it down. So maybe it isn't lighter than air? Or is the piece glued down?

> Non-conductive objects, such as plastics, could be coated with aerographite to make them conductive — without gaining weight.

While the material may be very light, I'm certain its weight is nonzero (and non-negative). This doesn't even make sense.

Fascinating material, dumb article.

sylvinus• 14 years ago

I think it's probably lighter than air if you weight it in a vacuum.

I think like a sponge in the photograph it has a fair amount of air in itself.

Just a guess though.

joesb2• 14 years ago

Air also has a fair amount of air in itself.

If 1 cube of a meterial has x% aerographite + (100-x)% air, while air has x% air + (100-x)% air, the material is still going to be lighter than air.

jpdoctor2• 14 years ago

> If it's lighter than air, doesn't it float away?

You are confusing density with buoyancy.

Stratoscope2• 14 years ago

Can you explain a bit more and help me with my confusion? Thanks!

joesb2• 14 years ago

> While the material may be very light, I'm certain its weight is nonzero (and non-negative). This doesn't even make sense.

I don't know, if you coat a plastic with air, does it get heavier?

TallGuyShort• 14 years ago

Coating plastic in this material would add mass, not weight. You can fill a balloon with helium, and in a vacuum it would be heavier because it has more "stuff" in it. But in our atmosphere, it is less dense than the air, so it floats because the air it displaces is pulled by gravity with greater force.

So the weight is non-zero, but it's actually negative in our atmosphere. It's mass is positive.

JulianMorrison• 14 years ago

Or to simplify the same thing, "it behaves like a bubble in water".

sageikosa• 14 years ago

Buoyancy. The weight is still positive (net force of gravity downward), but the air pressure is greater. In the case of the balloon, the added weight of the helium is overpowered by the increased air pressure due to the larger displacement volume, and the balloon follows the path of least resistance (lower air pressure, at higher altitude).

Groxx• 14 years ago

Specific to the water drop: that's a huge drop of water for that piece. Weigh that volume of air and compare it to a drop of water that size - there's no way it's even close. So even if it does float, the water would be more than sufficient to keep it down.

Dove• 14 years ago

A (dry) sponge is much lighter than water, but it might not float; when you put it in water, the holes fill up with water, and the question becomes whether the rest of the sponge is light enough to float.

It's the same thing here. When they say it's lighter than air, they're counting the whole structure's volume, with all its holes in it. When you put it in air, and the holes fill up with air, the question then becomes whether the rest of it is lighter than air on its own. (Probably not)

ph0rque2• 14 years ago

If a piece of aerographite were to be sealed on the outside, and all the air removed, then yes, it would float. But without this treatment, the air permeates the microstructure, and it does not float.

kps• 14 years ago

So, the question is — if you take a zeppelin-sized chunk of aerographite, seal the outside, and evacuate the air, will it hold up to the pressure?

ph0rque2• 14 years ago

You don't even need aerographite for that: http://www.dangermouse.net/gurps/zeppelin/vacuum.html

However, you need a material strong enough not to implode due to the outside pressure of air. Not sure how good material tech is for that.

Even if it were strong enough, you would have constant "leaks" of air into the vacuum cells. So you would need a vacuum pump working all the time. Still might be worth it, though.

js2• 14 years ago

Previous discussion[1] from when the paper was press released[2]:

1. http://news.ycombinator.com/item?id=4260778

2. http://www.uni-kiel.de/aktuell/pm/2012/2012-212-aerographit-...

eliben• 14 years ago

Nanotechnology is awesome, but most of it seems to be in early research stages. Any good references for nanotechnology products used commercially today?

Aerographite: six times lighter than air, conductive, and super-strong

Related Stories