German Scientists Create Aerographite, the Lightest Material in the World
sciencespacerobots.com
sciencespacerobots.com
Aerogels formerly held the record for least dense solid. They're not gels, but they're called aerogels because they're made from gels. As the name "aero" implies, they're mostly air, giving them incredible strength-to-weight ratios and insulating properties. Silica aerogels are translucent and quite amazing to hold; it's like holding a cloud.
Aerogels are made from colloids (a.k.a. gels), which are long chains of polymers formed in water. Free-floating around in the water, they form very long, intricate, 3-D maze-like structures. If you've ever made JELL-O, you've made (and eaten) a colloid. It’s the intricate structure of the colloid which keeps the suspended water from spilling out.
Silica aerogels are formed by removing the water from a silica gel, leaving only the maze like structure behind. This structure is very delicate, and if you attempt to evaporate the water out near room temperature/pressure, the capillary action of water will collapse the structure like a dried out jellyfish. However, if you heat and pressurize the system past the critical point, the water becomes a supercritical liquid and it can be removed without pulling the rest of the material inwards.
It appears that what they’ve done here is similar, except they use a multi-step process to deposit carbon on the colloid, then remove the colloid completely, leaving nothing but a carbon maze. I presume they can't make colloids out of carbon directly, hence the multistep process.
From Wikipedia on Aerogel (another very lightweight solid) [1], The lowest-density aerogel is a silica nanofoam at 1 mg/cm3, which is the evacuated version of the record-aerogel of 1.9 mg/cm3. The density of air is 1.2 mg/cm3 (at 20 °C and 1 atm). Only the recently manufactured metallic microlattices have a lower density at 0.9 mg/cm3.
How are they computing the density of the aerographite such that it doesn't float away (having 1/6 the density of air)? Are they only considering the mass of the carbon and not the internal air?!
So, could I claim to have the lightest material if I made a hollow, porous, giant hairball?
http://www.uni-kiel.de/aktuell/pm/2012/2012-212-aerographit-...
Interesting potential for batteries (quoted from above link):
"Due to its unique material characteristics, Aerographite could fit onto the electrodes of Li-ion batteries. In that case, only a minimal amount of battery electrolyte would be necessary, which then would lead to an important reduction in the battery's weight. This purpose was sketched by the authors in a recently published article. Areas of application for these small batteries might be electronic cars or e-bikes. Thus, the material contributes to the development of green means of transportation."
Owing to its interconnected tubular network structure, aerographite resists tensile forces much better than other carbon foams as well as silica aerogels. It has a very low Poisson ratio, as demonstrated by a complete shape recovery of a 3-mm-tall sample after it was compressed down to 0.1 mm. Its ultimate tensile strength (UTS) depends on material density...
How soon will we see this used instead of metal frameworks or latex foam? In aircraft wings, car seats, etc?
Even more interesting: Upon external compression, the conductivity increases, along with material density. Pressure-sensitive aircraft wings? Car seats that know what their occupants weigh?
Both of these things are pretty easy and cheap to do with existing technology.
http://en.wikipedia.org/wiki/Space_elevator#Cable
I don't know what the strength of this material is or its breaking length (a breaking length of 5,000 km is required for a space elevator), the abstract doesn't say so, but research like this is really exciting.
Now launch loops, that I could get excited about.
The density of air is 1.2 mg/cc.
FTA: "The substance weighs just 0.2 milligrams per cubic centimeter"
So why doesn't this thing just fly away, if its density is 0.2 mg/cc ?
It does point out a blurry line between substance and structure. At some point, the voids in the material get large enough that you would call it a structure, for instance, if you outlined a soccer ball in fine copper wire and removed the soccer ball it would certainly be even lighter than this, but you wouldn't call it a substance.
It's not new.
What is the density of a boat? The density of the boat as a whole is lower than water - so it floats.
But if you could only the materials it's made of they are all heavier.
So you have to know what you are describing.
That said, in Neal Stephenson's diamond age they used vacuum balloons as a floatation device. something that I hope we can build at some point.
I do wonder what use it could actualy be though. Not very strong, ok it's light but it's not much stronger than air going by that video. I do wonder if you could make a static drawn bellows with this to move air, but thats me being geek.
Anybody know what uses this could have beyond coffins for ants sent via beemail! Anybody know a use?
By what definition? Because according to Wikipedia, it's just the opposite: https://en.wikipedia.org/wiki/Aerographite#Structure_and_pro...
That said brittle is not realy scientific so I'll bow to that and kudos for the wiki link, covers potentual usage as well - thank you.
On the Aerographite wikipage it's called a "structural material".
Incidentally, there was a "carbon nanotube aerogel" that (AFAIK) has the exact same composition as this one and is listed at 1.5 mg/cc [2]. Weighing in a vacuum would seem a bit sensationalistic IMO.
Static friction? It probably would float for some time in air if it wasn't touching something and there is no breeze.
No. The atoms of carbon are still heavier than air, and no type of structure can alter that.
However it can be blown by a breeze and stay up that way - same way a cloud, which is heavier than air, stays up due to wind.
I would totally expect this stuff to be transparent based on the description. Shows what I know.
I wonder if this material, being made of carbon and likely having a similarly high surface area, would make a good capacitor.
As far as "flying away", from the video embedded in the linked article, you can see the aerographite is barely able to sit still on the table before the rod is introduced - one of them is about to fly away just sitting there. It just "looks" extremely light.