Thursday, 11 July 2013

Will the carbon nanotube wire rival copper?

Scientists have made a strong, lightweight wire from carbon that might eventually be a rival to copper.

It was the first time that the super-strong carbon wires, spun in a tiny furnace that looks like a candy floss machine with temperatures above 1,000°C, had been made "in a usable form" a millimetre thick.

Krzysztof Koziol of the Cambridge University's department of materials science and metallurgy said commercial applications were still years away as its ability to conduct electricity needs to be improved but that "our target is to beat copper".

Wire made in the laboratory from carbon nanotubes (CNTs) – microscopic hollow cylinders composed of carbon atoms – is 10 times lighter than copper and 30 times stronger, the university said in a statement.

Among advances, the scientists found a way to solder CNTs to metal, something that had previously not been possible, though a big drawback for CNTs is that a kg of copper is 2.5 times more conductive than a kg of CNT.

For the next few years, Cambridge University would focus on copper and CNT hybrids, a programme to create "ultra-conductive" copper that is supported by the copper industry. In some blends, tiny amounts of carbon improve copper's conductivity.

The International Copper Association, representing producers of more than half the world's copper, said that mass production of ultra-conductive copper could be 10 years away if the science can be improved.

60 per cent of all copper sold worldwide was to carry electricity.

Koziol, however, said pure CNT wires could have more immediate uses because they are more flexible than copper. That could be valuable in moving parts such as robot arms or in planes or cars where flexibility is more important than conductivity.

Weight can be crucial.

About a third of the weight of a large space satellite, weighing 15 tonnes, is typically copper. A Boeing 747 jumbo jet uses as much as 135 miles of copper wiring, weighing more than 2 tonnes, the university said.

The UK National Grid said a benefit of CNTs, if developed at commercial scale at a competitive cost, was that they can operate at high temperatures.

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