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New materials developed that are as light as aerogel, yet 10,000 times stronger

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June 22, 2014

Lawrence Livermore Engineer Xiaoyu 'Rayne' Zheng studies a macroscale version of the unit ...

Lawrence Livermore Engineer Xiaoyu 'Rayne' Zheng studies a macroscale version of the unit cell that makes up the the ultralight, ultrastiff material (Image: Julie Russell/LLNL)

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Imagine materials strong enough to use in building airplanes or motor cars, yet are literally lighter than air. Soon, that may not be so hard to do because a team of researchers from MIT and Lawrence Livermore National Laboratory (LLNL) have developed new ultra-lightweight materials that are as light as aerogel, but 10,000 times stiffer, and may one day revolutionize aerospace and automotive designs.

Aerogels are incredibly light, so light that the record holder, aerographene, boasts a density of just 0.16 mg/cm3. Currently, aerogels are used for insulation, tennis racquets, as a means of controlling oil spills, and were used on the NASA Stardust mission to collect samples from a comet’s tail. Unfortunately, despite its seemingly ephemeral nature, its very much a solid and will shatter if pressed hard enough, so its use is limited.

The new materials developed by the MIT/LLNL team aren't aerogels, but are metamaterials. That is, artificial materials with properties that aren't found in nature. The idea is to structure it, so that it has the lightness of aerogel, but is much stronger. The strength of the new materials comes from their geometric structure, not their chemical composition.

The new materials were made using projection micro-stereolithography, a form of desktop 3D printing that works on a microscopic level and can create highly complex, three-dimensional microstructures layer by layer very quickly for easy prototyping. It involves projecting a beam of ultraviolet light into a tank of polymers, responsive hydrogels, shape memory polymers, or bio-materials using the digital stereolithography technique in the form of masks, similar to those used to create microchips, to shape the layers.

Projection micro-stereolithography operates on a very small scale that allows the formation of "microlattices," which are much like trusses and girders. Materials can even be switched during fabrication. According to the team, it can be applied to many different materials, including polymers, metals and ceramics, which is exactly what the team did using a variety of constituent materials.

Firstly, the LLNL/MIT team made a polymer template coated with a metal film 200 to 500 nanometers thick, then the polymer base was melted away, leaving behind the metal in the form of thin-film tubes.

The team then used the same technique but replaced the metal with ceramic to create ceramic tubes about 50 nanometers thick, which produced a material with the properties of an extremely stiff aerogel, four orders of magnitude stiffer than conventional aerogel, but with the same density.

The LLNL research team with examples of microstructure cells (Image: LLNL)

The next step was to create a ceramic-polymer hybrid, which is a polymer with ceramic nanoparticles embedded into it. This relied on a slightly different process, with the polymer removed thermally, allowing the ceramic particles to densify into a solid. When the polymer was removed, the result was a stiff, ultralight ceramic solid instead of hollow tubes.

"These lightweight materials can withstand a load of at least 160,000 times their own weight," said LLNL Engineer Xiaoyu "Rayne" Zheng. "The key to this ultrahigh stiffness is that all the micro-structural elements in this material are designed to be over constrained and do not bend under applied load."

The team sees the materials as one day being used to develop parts and components for aircraft, motor cars, and space vehicles, and that in practical use, the material could end up being 100 times stronger than the experimental versions.

The research team’s results were published in the journal Science.

Sources: LNLL, MIT

About the Author
David Szondy David Szondy is a freelance writer based in Monroe, Washington. An award-winning playwright, he has contributed to Charged and iQ magazine and is the author of the website Tales of Future Past.   All articles by David Szondy
14 Comments

Very good, but it's not transparent, and so can't be used in glazing application the way aerogel could (I'm think thin double glazing, no more than 12-13mm / 1/2in thick), although maybe as a window frame...

MattII
23rd June, 2014 @ 12:15 am PDT

Could we at least not use "strong" and "stiff" interchangaably? This is supposed to be about engineering.

Bob Stuart
23rd June, 2014 @ 01:19 am PDT

All very impressive, but it is difficult to see a practical application without major developments in the production process. Whilst it might be possible to manufacture prototype components using this process, unless they can be turned out at mass production volumes, what value any test results from the components in developmental use.

I suppose the exception would be space vehicle components, which can hardly be said to be mass produced, anyway.

Over and above those considerations, I suppose the major concern would be its performance under overload condtions. I expect that they would produce a sudden catastrophic collapse, which is not the best outcome most of the time. Though how you make it malleable in order to increase its resilience is an area requiring further work, I suspect.

Materials such as this will have come of age when they can be used for making the reciprocating components of an ICE and perhaps even the cylinder block. I suspect that crash worthiness requirements would preclude their being used for vehicle body shells and suchlike. Though this is not too negative a point because there might come a time when vehicles could be so lightweight that one could not go out for a drive in wind conditions above six on the beaufort scale and crosswind parking would form an essential part of the driving test. As for fording a river, forget it if the water comes above the hubcaps.

Mel Tisdale
23rd June, 2014 @ 04:07 am PDT

I think this was announced a couple weeks ago. That or someone with micro latices using a very similar fabrication method was announced.

This is awesome work. Once the speed of manufacture increases this could replace structural components that are currently very heavy solids at the moment. I remember seeing a graphic from one of their competitors showing that using micro latticed steel a 1 ton 1 inch thick steel plate could be replaced by a micro-lattice that weighed a pound or less. Imagine a tractor trailer that only weighed 2 tons rather than the current 15.5+ tons.

The speed of manufacture is the current limiting factor, but there are groups working toward solving that issue. This document (http://www.researchgate.net/publication/51808274_Ultralight_metallic_microlattices/file/9c96052505d79b0797.pdf) is from a team developing a scalable process they think could generate several cubic meters of the material per hour.

VirtualGathis
23rd June, 2014 @ 06:53 am PDT

I'm still waiting to see the killer applications using AeroGel for something.

AeroGel has been around for a long time, but it is still little better than a novelty.

flink
23rd June, 2014 @ 09:17 am PDT

Imagine this competing with carbon fiber and Al car bodies. The pressure to lower manufacturing costs would give us inexpensive, ultralight cars. Next, we need computer generated & air tunnel tested aerodynamic design like the Aptera. Suddenly BEVs will have 4-500 mile range. All that's left is to come up a quick charge (under 10 minutes) and bye-bye ICE.

Don Duncan
23rd June, 2014 @ 09:31 am PDT

The implications are spectacular!

A brick of this stuff, wrapped up in an airtight membrane, "containing" vacuum, could be the basic building block for incredible airships!!

Remember; Vacuum is lighter that Hydrogen or Helium!

Even floating cities, like the one in "Star Wars, The Empire Strikes Back", should be feasible.

The only drawback is the huge amount of "Cavorite" needed.

...for now...

Alfred Max Hofbauer
23rd June, 2014 @ 09:44 am PDT

As a filmmaker, this is exciting. Among many other uses, if this could be mass-produced it would make great combination soundproofing/structural walls for sound stages. If the cost was reasonable, the walls could be much thinner than what is currently used in sound stages, reducing costs and real estate requirements. If the cost is low enough, it could also be used to make the walls of sets light enough that a single person could set them up and break them down.

Dave Andrews
23rd June, 2014 @ 11:27 am PDT

Mass produce, awesome, many uses for.

Stephen N Russell
23rd June, 2014 @ 04:27 pm PDT

@Alfred Max Hofbauer

Disturbingly you might be correct. The problem with this has always been strength under compression. The back of this envelope I have in front of me suggests that this material is strong enough to support such a structure. Or at least within an order of magnitude of strong enough.

If it can be increased in strength one hundred fold as the article suggests then it might compete with Helium for lift per unit volume.

Not sure it would ever be economical compared with just plain ol Hydrogen though...

crizh
23rd June, 2014 @ 05:16 pm PDT

Yes, great work, and lots of great potential uses in the comments.

But, it is important in all this micro-work, to avoid 'the next asbestos' problem. If we make super-thin fibres, and then this material is used in products which are eventually discarded (or worse - used in packaging) then we might be introducing very fine hard fibres of precisely the thinness that can cause irreversible damage to lung tissue.

These issues need to be thought-through and tested, whether nano-particle or nano-matrix. It is less of an issue if the matrix does not further degrade over time, even after being crushed.

Graeme Harrison
23rd June, 2014 @ 07:01 pm PDT

@crizh

Another problem is that such "Cavorite" bricks would have a nasty tendence to float around!

We already have lots of orbital trash, but this would add the (all new) problem of "stratospheric trash"!

As soon as someone destroys a capital airship, huge amounts of bricks would be spilling upwards, into the stratosphere, hindering air travel and space access.

...like a minefield to any re-entering spacecraft...

I can even envision someone using UV-degradable "Cavorite" bricks for just such a purpose!

Therefore, any such bricks MUST be made UV-degradable...

Alfred Max Hofbauer
24th June, 2014 @ 07:32 am PDT

If you could custom make a Spherical pattern for this stuff, then you could skin it over and create a bubble. Suck the air out of it and it would float.

Matthew Bailey
7th July, 2014 @ 08:21 am PDT

@ Virtual Gathis

" Imagine a tractor trailer that only weighed 2 tons rather than the current 15.5+ tons."

While you're at it, imagine the poor bastard who has to keep the thing on the road while "deadheading" in a 10 mph crosswind. Even fully loaded, it would be more of a challenge to keep it upright and in the lane than a full-mass trailer, fully loaded.

rocketride
14th July, 2014 @ 11:39 am PDT
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