Light as a graphite tube
20 Jul 2012 by Evoluted New Media
At just 0.2mg per cubic centimetre, Aerographite is the lightest material in the world.
Aerographite is a network of porous carbon tubes three-dimensionally interwoven at nano and micro levels; it’s lightweight; stable; electrically conductive; ductile; and non-transparent. It’s also very strong.
“Our work is causing great discussion in the scientific community,” said Matthias Mecklenburg, a PhD student from the Hamburg University of Technology (TUHH). “Aerographite weighs four times less than the world-record-holder.”
The previous record-holder was a nickel-based tube with porous walls, but since carbon has a lower atomic mass than nickel, these tubes are lighter. The highly resilient material also has excellent compression – it can be compressed up to 95% and pulled back to its original form without any damage – and tension load.
The tubes are made from a powdered zinc oxide which colleagues at Kiel University (KU) transformed into a crystalline form by heating to 900°C. From this, they made a kind of pill which contained micro and nano structures called tetrapods which interweave and form a stable entity – the network that is the basis for Aerographite.
Researchers at TUHH placed the pill in a reactor to undergo chemical vapour deposition, heating it up to 760°C.
“In a streaming gas atmosphere that is enriched with carbon, the zinc oxide is being equipped with a graphite coating of only a few atomic layers,” said Professor Karl Schulte. “This forms the tangled-web structures of the Aerographite.”
Hydrogen is also introduced, which reacts with the oxygen in the zinc oxide, releasing steam and zinc gas. What is left behind is a characteristic interwoven, tube-like carbon structure.
“The faster we get the zinc out, the more porous the tube’s walls get and the lighter the material,” said Mecklenburg. “There is considerable scope.”
The material has endless potential applications: it could fit onto the electrodes of Li-ion batteries; be used in electronics for aviation and satellites; or used as an absorbent for persistent water pollutants.
