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Nanoparticles for energy, explosions

Aluminum, the stuff of cans, explodes in its nano form. A small start-up has decided to harness that property.

Nanotechnology specialist QuantumSphere has developed technology that eventually could help heat homes--or blow them up.

The San Diego-based start-up has created a manufacturing process for producing small, stable metallic particles that consist of only a few atoms. By reducing the number of atoms per particle, manufacturers can better exploit the inherent properties of these elements in chemical reactions.

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What's new:
Start-up QuantumSphere devises a manufacturing process designed to help get nanometals into more products.

Bottom line:
Nanotech versions of aluminum and nickel point the way to faster rockets, better bombs and cheaper fuel cells. But QuantumSphere is heading into a tough marketplace.

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With aluminum, that means more powerful explosions. Munitions makers will likely be able to create aerial bombs that are smaller and lighter, but more powerful than current weapons. A rocket with nanoaluminum-enhanced fuel will reach a target velocity faster.

"It will accelerate to Mach 8 because of the higher burn rate," said Douglas Carpenter, chief scientific officer and co-founder of QuantumSphere. "If you can shoot someone down before they can shoot you, that is good."

By contrast, nanonickel could be used to replace platinum and other fairly expensive elements in catalytic converters and fuel cells. This shift could lead to cheaper hydrogen fuel cells for homes and cars in the growing alternative-energy market. Some Japanese manufacturers will come out with hydrogen fuel systems for homes in the first quarter of next year. Both metals can also be used in new types of coatings.

"Nickel is pretty much a garden-variety material," said QuantumSphere CEO Kevin Maloney. "It is a direct replacement for platinum."

NASA, the U.S. Air Force, the U.S. Navy and Ballard Power Systems, among others, are already customers.

As space-age as it sounds, nanotechnology--the science of making products out of components or molecules that measure less than 100 nanometers (a nanometer is a billionth of a meter)--has begun to sneak into the general market. Pants, bicycle components and car parts sprinkled with specialized nanoparticles have already, or soon will, come out. Socks with silver nanoparticles aim to prevent foot odor by killing bacteria.

Within the next 10 years, it's possible that semiconductor manufacturers may draw on nanotechnology techniques to produce memory chips or microprocessors consisting of self-assembling molecular chains.

But the nanometals market will likely be difficult and competitive, said Matthew Nordan, vice president of research at Lux Research, which studies the nanotechnology business. The huge industrial conglomerates and defense agencies that will be the first customers are also notoriously conservative.

Still, interest is growing. General Motors, for instance, is tinkering with nanoscale aluminum to produce shaped metal parts. Currently, these sorts of parts are made of two or more pieces of metal riveted together. By cooking up a unified part, GM can cut labor and material costs, Nordan said.

Car buyers needn't be worried about their vehicles going kaboom. The nanoaluminum won't blow up because of a coating that will be applied. Potentially, nanofused car parts will be lighter, too, (and consequently enjoy better gas mileage) because less metal needs to be incorporated into the materials mix to achieve the same levels of strength and durability.

Bigger isn't necessarily better
By definition, nanoscale components are small--a human hair, on average, measures 90,000 nanometers wide. But it's that very diminutive stature that is of great importance--the tininess of the particles exaggerates existing properties or uncovers new ones in the base material.

The change in behavior derives largely from the vast number of molecules that can simultaneously participate in a chemical reaction. With regular bulk materials, only the top layer of atoms participates in a reaction. With nanomaterials separated into independent granules, almost every atom reacts, because almost every atom is exposed.

Take the case of aluminum. The somewhat vigorous reaction between bulk aluminum and oxygen turns, in the nanotech context, into a massive outburst of heat and energy. Nanoaluminum, in fact, will explode on contact with air. The atoms are the same as the ones used in aluminum cans, but the nanoform causes aluminum to behave drastically differently.

QuantumSphere has been able to produce aluminum particles consisting of about seven atoms and measuring 2 nanometers across. A pinch of it can have as much surface area, chemically speaking, as a basketball.

"The surface area, really, is the key to nanoparticles in general," Carpenter said. "The smaller you make them, the stronger (the reaction) is."

Microsize aluminum particles already get incorporated into rocket fuels and bombs, but nanoaluminum improves on the formula. In tests conducted over New Mexico, the Air Force launched nanoaluminum-enhanced warheads that packed twice the explosive power of current weapons. QuantumSphere plans to further discuss how to adopt nanoaluminum with the U.S. Naval Warfare Center in November.

The aluminum particles could also find their way into airbags, replacing the somewhat toxic particles used now to eject the bags. The particles present a potential toxic danger to factory workers who handle the materials over long periods of time, not car passengers. Nanoaluminum will be safer, the company asserted. QuantumSphere is also studying potential toxicity with a team at Rice University, a hotbed for nanotech research.

Quality control
QuantumSphere's nanoparticles are made by vaporizing a wire inside a vacuum. Individual atoms then coalesce into spheres, which float in a liquid. The surface of the spheres is then slightly oxidized, which stabilizes the particles so that they can be exposed to air. The oxide coating also permits engineers to better control the reaction.

The company's patents largely revolve around creating particles that are uniform in size. "You can't have basketballs, golf balls and softballs all mixed together," Maloney said. "You need golf balls."

A gallon of the nanoaluminum costs $1,200 and comes in a paint can. Nanonickel, meanwhile, costs about $2,250 a pound--but that's still about 75 times cheaper than platinum, one of the crucial elements in catalytic converters, according to Maloney.

"Nickel is going to far outweigh aluminum demand" in a few years, Maloney said.

While the current prices are high, they're an improvement--producing particles this size just a few years back was unthinkable. "Five years ago, nanoaluminum was $10,000 a pound," Maloney said. Hence, few of the large aluminum giants, like Alcoa, dedicated much effort to it. A Russian company developed a type of nanoaluminum, but security concerns have kept U.S. defense agencies from working with it.

Prices are also expected to fall over time. QuantumSphere recently opened a forge that is capable of producing 200 pounds of nanoaluminum a month, 800 pounds of nanonickel or a combination of the two. The plant will be expanded so that 1,200 pounds of aluminum or 3,000 pounds of nickel can be fabricated. (The difference in weight comes as a result of nickel's heavier atomic weight.) Ultimately, QuantumSphere will likely partner with or get acquired by one of the established materials companies for further mass production.

The company currently only has eight employees but will likely expand to 12 in the relatively near future. It also plans to seek venture funding in the first quarter.