April 25, 2014

How to Make Graphene in Your Kitchen Blender

Filed under: Cool, Gadgets — bferrari @ 12:54 pm


Making Graphene in a common blender

Scientists whip up ‘wonder material’ with blender, detergent

Don’t try this at home. No really, don’t: it almost certainly won’t work and you won’t be able to use your kitchen blender for food afterwards. But buried in the supplementary information of a research paper published today is a domestic recipe for producing large quantities of clean flakes of graphene.

The carbon sheets are the world’s thinnest, strongest material;  electrically conductive and flexible; and tipped to transform everything from touchscreen displays to water treatment. Many researchers — including Jonathan Coleman at Trinity College Dublin — have been chasing ways to make large amounts of good-quality graphene flakes.

In Nature Materials, a team led by Coleman (and funded by the UK-based firm Thomas Swan) describe how they took a high-power (400-watt) kitchen blender and added half a litre of water, 10–25 milliliters of detergent and 20–50 grams of graphite powder (found in pencil leads). They turned the machine on for 10–30 minutes. The result, the team reports: a large number of micrometer-sized flakes of graphene, suspended in the water.

Coleman adds, hastily, that the recipe involves a delicate balance of surfactant and graphite, which he has not yet disclosed (this barrier dissuaded me from trying it out; he is preparing a detailed kitchen recipe for later publication). And in his laboratory, centrifuges, electron microscopes and spectrometers were also used to separate out the graphene and test the outcome. In fact, the kitchen-blender recipe was added late in the study as a bit of a gimmick — the main work was done first with an industrial blender (pictured).

Still, he says, the example shows just how simple his new method is for making graphene in industrial quantities. Thomas Swan has scaled the (patented) process up into a pilot plant and, says commercial director Andy Goodwin, hopes to be making a kilogram of graphene a day by the end of this year, sold as a dried powder and as a liquid dispersion from which it may be sprayed onto other materials.

“It is a significant step forward towards cheap and scalable mass production,” says Andrea Ferrari, an expert on graphene at the University of Cambridge, UK. “The material is of a quality close to the best in the literature, but with production rates apparently hundreds of times higher.”

The quality of the flakes is not as high as that of the ones the winners of the 2010 Nobel Prize in Chemistry, Andre Geim and Kostya Novoselov from Manchester University, famously isolated using Scotch Tape to peel off single sheets from graphite. Nor are they as large as the meter-scale graphene sheets that firms today grow atom by atom from a vapour. But outside of high-end electronics applications, smaller flakes suffice — the real question is how to make lots of them.

Although hundreds of tons of graphene are already being produced each year — and you can easily buy some online — their quality is variable. Many of the flakes in store are full of defects or smothered with chemicals, affecting their conductivity and other properties, and are tens or hundreds of layers thick. “Most of the companies are selling stuff that I wouldn’t even call graphene,” says Coleman.

The blender technique produces small flakes some four or five layers thick on average, but apparently without defects — meaning high electrical conductivity. Coleman thinks the blender induces shear forces in the liquid sufficient to prise off sheets of carbon atoms from the graphite chunks (“as if sliding cards from a deck”, he explains).

Kitchen blenders aren’t the only way to produce reasonably high-quality flakes of graphene. Ferrari still thinks that using ultrasound to rip graphite apart could give better materials in some cases. And Xinliang Feng, from the Max Planck Institute for Polymer Research in Mainz, Germany, says that his recent publication, in the Journal of the American Chemical Society, reports a way to produce higher-quality, fewer-layer graphene at higher rates by electrochemical means. (Coleman points out that Thomas Swan have taken the technique far beyond what is reported in the paper.)

As for applications, “the graphene market isn’t one size fits all”, says Coleman, but the researchers report testing it as the electrode materials in solar cells and batteries. He suggests that the flakes could also be added as a filler into plastic drinks bottles — where their added strength reduces the amount of plastic needed, and their ability to block the passage of gas molecules such as oxygen and carbon dioxide maintains the drink’s shelf life.

In another application altogether, a small amount added to rubber produces a band whose conductivity changes as it stretches — in other words, a sensitive strain sensor. Thomas Swan’s commercial manager, Andy Goodwin, mentions flexible, low-cost electronic displays; graphene flakes have also been suggested for use in desalination plants and even condoms.

In each case, it has yet to be proven that the carbon flakes really outperform other options — but the new discoveries for mass-scale production mean that we should soon find out. At the moment, an array of firms is competing for different market niches, but Coleman predicts a thinning-out as a few production techniques dominate. “There are many companies making and selling graphene now: there will be many fewer in five years’ time,” he says.




April 22, 2014

Felix Re-Entry Suit

Filed under: Cool, Earth, Military, Space Ships — bferrari @ 12:10 pm


In low earth orbit, an astronaut abandons his doomed craft and returns to earth.

Watching the Felix Baumgartner jump was one of the highlights of the year for me. I was really blown away, and this is my homage to that moment: a theoretical look at what advances his jump could bring for space exploration and astronaut survivability. In this case it’s a specialized hardened suit that can allow for re-entry from low earth orbit. Not a jump you want to make, but when you have to you’ll want to be wearing this suit.



April 21, 2014

SpaceX Wants to Send a Positively Massive Rocket to Mars

Filed under: Cool, Gadgets, Mars, Military, Space Exploration, Space Ships — bferrari @ 2:23 pm

The future of spaceflight will be powered by ion engines and warp drives, right? Not just yet. There is still some uncharted territory in the world of liquid-fueled rockets, which have been powering spacecraft since the 50s, and SpaceX is testing the waters with its new Raptor engine. It could be the engine that, if Elon Musk gets his wish, propels the first colonists to Mars.

Right now the Raptor looks like it will be developed to deliver 1 million pounds of thrust at launch, which is certainly a step up from SpaceX’s existing engines—SpaceX’s Merlin 1D delivers about 147,000 pounds at launch. The Raptor will even beat out the Space Shuttle’s main engine, which delivered 375,000 pounds of thrust at launch. In other words, the Raptor is expected to be a huge engine, dwarfed only by the F-1 engine powering the gigantic Saturn V rocket.

Can SpaceX build a rocket engine to rival the giants? The firm has had good luck developing rocket engines in the past. Its Merlin 1D engine, which uses the traditional mixture of kerosene and liquid oxygen, has the highest thrust-to-weight ratio of any engine currently in use. But it still uses the same basic technology of all liquid rocket engines that came before it.

RELATED: NASA Is Resurrecting the Most Powerful Rocket Engine Ever Built

Liquid-fueled rockets work by mixing a fuel and an oxidizer in a combustion chamber before the mixture is ignited and blasted out of a nozzle. For a powerful reaction to occur, large quantities of the liquid fuel and the oxidizer must be fed into a rocket’s combustion chamber quickly and under high pressure. This flow of liquids is driven by a turbopump, a system that is powered by a small amount of fuel “pre-burning.” A similar process happens to get the oxidizer into the combustion chamber.

SpaceX's Merlin 1D rocket engine being tested. (SpaceX)

SpaceX’s Merlin 1D rocket engine being tested. (SpaceX)

Liquid-fueled engines typically send a small amount of fuel and oxidizer through the preburners; the bulk of the liquids are sent directly into the combustion chamber. But what if this weren’t the case?

The US Air Force and NASA have both considered what’s called a “full-flow cycle” design, which sends all fuel through turbopumps. It has one important advantage: more fuel and oxidizer passing through the preburners will drive the turbo pumps harder, increasing the pressure inside the combustion chamber and in turn the rocket engine’s performance.

A full-flow design has never been used in the United States, but it’s the kind of design SpaceX is currently pursuing for its Raptor engine.

SpaceX first revealed its new engine design at the AIAA Joint Propulsion conference in July of 2010. They were introduced as the powerhouses for the company’s future Falcon X and Falcon XX rockets. The first new engine was the Merlin 2, an engine of similar design but more efficient than the Merlin 1-D. The second engine presented was the Raptor, a staged combustion engine using liquid oxygen and hydrogen to power heavy rockets.

SpaceX says its future Falcon Heavy rocket will be the most powerful rocket in existence. Its first stage will be powered by 27 Merlin rocket engines, which are about an eighth the size of the Raptor engine planned. (SpaceX)

SpaceX says its future Falcon Heavy rocket will be the most powerful rocket in existence. Its first stage will be powered by 27 Merlin rocket engines, which are about an eighth the size of the Raptor engine planned. (SpaceX)


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