The ‘world’s darkest material’, unveiled this week at Farnborough Airshow, could improve optical performance in everything from space telescopes to airborne guidance systems.
The carbon nanotube-based material developed by British firm Surrey NanoSystems reflects as little as 0.035 per cent of light from the visible spectrum, compared to 8 to 10 per cent in good quality black paint and 0.04 per cent in a lab sample created by Nasa that holds the current Guinness World Record for the world’s darkest material.
Limiting stray light could vastly improve the ability of sensitive telescopes to see the faintest stars, or help electro-optical imaging and target-acquisition systems achieve new levels of range and performance.
More importantly, the firm’s proprietary ‘photo-thermal chemical vapour deposition’ technique means that its Vantablack material can be applied to light-weight, temperature-sensitive materials such as aluminium, something previous techniques have been unable to achieve.
“The breakthrough is not only achieving such low reflection, but also being able to grow it so you get adhesion when applied to metals like aluminium, which is the bread and butter of space. It’s being able to grow on that material without melting or deforming it,” said chief technology officer Ben Jensen.
“Nasa has been applying its material to titanium and silicon. If you think about how much it costs to launch something into space, those materials are two to three times heavier than aluminium.”
Typical chemical vapour deposition methods require temperatures in the 700 to 800°C range, which precludes their use on sensitive electronics or materials with relatively low melting points, but during work on semiconductor technology the firm’s scientists hit on a method to overcome this problem.
Rather than heating from below through the substrate as traditional methods do, the team applied heat from above, which allowed them to cool the substrate simultaneously and maintain temperatures of about 400°C.
“It was a eureka moment,” said Jensen. “We were working long hours in the lab going completely nuts because what we were doing wasn’t working. We were sitting in the pub in Guildford one night and I said, ‘Oh’ and that oh turned into what we have now.”
It wasn’t until the firm teamed up with the National Physical Laboratories and Enersys’ ABSL Space Products division that they realised their technique could be applied to the manufacture of ‘super-black’ materials. They applied for funding from the UK Technology Strategy Board’s Space for Growth programme and completed a two year development and test programme last December.
The firm is currently two years into the five year process to get their material fully accredited for use in space, but the applications for the material also include all manner of spectrometers, terrestrial telescopes, passive and active infrared systems and airborne guidance systems and the firm has already delivered its first order to an defence aerospace company, unnamed for security reasons.
“They term it ‘photon-starved’ applications and there are so many of them,” said business director Steve Northam. “Originally we space was the only one, but since we’ve got into conversations with people we’ve found that the applications are just so varied.”
The firm expects most of its business to come from technology partnerships licensing its methods to larger manufacturers, and while the new material will come at a premium compared to competitors, Northam maintains the cost will be competitive.
“There’s a benefit through life as well in terms of robustness of the material” he said. “One of the strengths of this material is that it doesn’t outgas, or lose any particles. A lot of competitors lose particles over time, which renders the equipment obsolete or requires through-life maintenance.”
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