Nanoparticle research blows open new possibilities
Published: 22 Oct 2004 12:15 BST
Take the case of aluminium. The somewhat vigorous reaction between bulk aluminium and oxygen turns, in the nanotech context, into a massive outburst of heat and energy. Nanoaluminium, in fact, will explode on contact with air. The atoms are the same as the ones used in aluminium cans, but the nanoform causes aluminium to behave drastically differently.
QuantumSphere has been able to produce aluminium particles consisting of about seven atoms and measuring 2nm 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 aluminium particles already get incorporated into rocket fuels and bombs, but nanoaluminium improves on the formula. In tests conducted over New Mexico, the US Air Force launched nanoaluminium-enhanced warheads that packed twice the explosive power of current weapons. QuantumSphere plans to further discuss how to adopt nanoaluminium with the US Naval Warfare Center in November.
The aluminium 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. Nanoaluminium 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 vaporising 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 nanoaluminium costs $1,200 and comes in a paint can. Nanonickel, meanwhile, costs about $5,000 a kilo -- 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 aluminium demand", 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, nanoaluminium was $10,000 a pound [about $4,500 per kg]," Maloney said. Hence, few of the large aluminium giants, like Alcoa, dedicated much effort to it. A Russian company developed a type of nanoaluminium, but security concerns have kept US defence agencies from working with it.
Prices are also expected to fall over time. QuantumSphere recently opened a forge that is capable of producing 90kg of nanoaluminium a month, 360kg of nanonickel or a combination of the two. The plant will be expanded so that 550kg of aluminium or 1400kg 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.
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