Mini but mighty material breaks strength record
30 April 2007
Scientists have unveiled a record-breaker - a mini but mighty new contender for the world's strongest material. The fibres are made from tiny carbon nanotubes and could soon be spun out to make a new breed of bulletproof body armour.
Antenna investigates...
Carbon nanotubes are less than a millionth of a centimetre wide but up to a millimeter long.
Image: Krzysztof Koziol
Carbon nanotubes are tiny hollow particles made from layers of carbon, smaller than the eye can see. There are lots of different carbon nanotubes and their properties depend on their size and structure.
Now scientists have created a super-strong fibre made from carbon nanotubes that could be an ideal material for bulletproof armour. The fibres are tough enough to absorb the impact of a bullet without deforming, stopping it from penetrating the wearer's body.
This microscopic image shows a single fibre made up of carbon nanotubes.
Image: Krzysztof Koziol
'At very short lengths our fibres have strengths greater than any material we've ever seen before,' says Krzysztof Koziol, a nanotube researcher from Cambridge University. 'Overall the fibres have a similar strength to Kevlar, the material that most body armour is currently made of.'
Krzysztof Koziol, nanotube researcher, University of Cambridge.
Image: Krzysztof Koziol
The team's new nanofibres have several properties that promise to make them even tougher than Kevlar. Kevlar starts to break down in ultraviolet light and at temperatures above 400 degrees Celcius. But the Cambridge nanofibres can survive undamaged in ultraviolet light and temperatures up to 600 degrees Celcius.
'We also tested how defects in the fibres affect their original strengths,' adds Krzysztof. 'For Kevlar, any defects reduce its strength by about half, but our fibres retained almost a hundred per cent of their strength.'
Carbon nanotube fibres look like this under a high-powered microscope.
Image: Krzysztof Koziol
Scientists have been studying nanotubes for years, but until now they haven't found many practical uses for them. One problem is that it's hard to make them into useful materials. The Cambridge team think they've found the answer.
'We've discovered a way to create carbon nanotubes and turn them into strong fibres in one continuous process,' explains lead researcher Alan Windle. 'This makes it quick and easy to produce useful nanotube-based materials.'
Alan Windle, lead nanotube researcher, University of Cambridge.
Image: Alan Windle
Alan's team constructed their nanotube fibres by injecting a mixture of alcohol, hydrogen and iron into a hot furnace. The high temperature makes these chemicals react to form a smoke made of long nanotubes.
'Because the nanotube fibres are so long, they tangle up together, forming a substance we call elastic smoke,' explains Alan. 'We can grab this smoke and wind it up continuously as a high-performance fibre.'
This video shows carbon nanotube fibres being spun directly out of the furnace.
Video: Alan Windle
What does the future hold for nanotube fibres?
'Now we want to find a way to get an ultra-high strength over the whole fibre, not just comparatively small parts,' says Alan. 'We're going to develop the fibres' chemistry, try to get rid of any defects and work on perfecting the manufacturing process.'
'At the moment we're trying to turn our fibre-making technique into an industrial process,' adds Krzysztof. 'If we can do this, we'll be able to make products straight away. Hopefully we'll start to see our new fibres in use within the next few years.'
When the team perfect their fibre-making process, they hope to be able to make products like this bulletproof vest.
Image: istockphoto.com/Rockfinder
'These carbon nanotubes could potentially have a whole host of uses from body armour to electrical cables to gas sensors,' says Mike Cronkshaw, materials curator at the Science Museum. 'The challenge is to scale this technology up so that it works at a commercial size.'
Mike Cronkshaw, materials curator, Science Museum.
Image: Science Museum