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Chemical Technology • March 2016
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one in nanotech: atomic layer deposition (ALD). Used most
commonly in the production of microprocessors, by alternat-
ing a sequence of gas deposition on a substrate, complex
nanoscopic components can be created. (Chemical vapour
deposition is similar to ALD but here the different vapours
are never present simultaneously.)
NASA’s problem is that its approach requires the oxide-
coated objects to be baked at 750 °C . That seriously limits
the nature of the objects they can coat as well as introduces
new problems. A new spectrograph added to Hubble in 1997
underwent thermal expansion and shortened the lifespan
of the instrument.
In 2014, researchers at Surrey University released a
paper entitled “The partial space qualification of a vertically
aligned carbon nanotube coating on aluminium substrates
for Earth Orbit applications”. Evangelos Theocharous,
Christopher Chunnilall and their colleagues described the
low-temperature fabrication of “NanoTube Black, a Verti-
cally Aligned carbon NanoTube Array (VANTA) on aluminium
substrates”.
Low-temperature in their case means 400 °C. This
massively increases the range of materials they are able to
coat. Their first commercial orders were delivered to clients
in July 2014. Clients in the aerospace industry tested the
material for mass loss, outgassing, shock, vibration and
temperature cycling. It passed happily.
The Hubble is reaching the end of its work life and its
successor, the James Web Space Telescope, is being de-
veloped with a launch target of 2018. It’s highly likely that
VantaBlack will be used as a coating.
Fortunately for Surrey NanoSystems, there’s more work
out there than the occasional space telescope. There are
a large number of sensors which measure light but need
to suppress stray light. Solar collectors are used to absorb
radiation and convert it into heat. And there are a fewmore:
spectroscopy used in medical diagnostics (eg, in blood
tests), cinematography (both on production and in projec-
tion), and in architecture.
One of Surrey NanoSystems latest developments is a
spray paint version. This only absorbs 99,8 % of incident
light (compared to their main product’s 99,965 %) but it can
be applied at room temperature to any object.
The British Science Museum currently has a display
one can visit. Ben Jensen, at Surrey NanoSystems, makes
a minor dig at NASA in his comments about the display:
“Vantablack S-VIS is so effective that its performance far
outstrips any other known paint or super-black coating,
achieving a reflectance of just 0,20 %. This is significantly
less reflective than, for example, the super-black paint used
for managing stray-light in the Hubble Space Telescope.”
Sir Anish Kapoor, an architect and sculptor, intends us-
ing VantaBlack in a new artwork (after he gets his security
certification because this is a listed product).
Both NASA’s super-black and Surrey NanoSystems’ Van-
tablack have a very wide light absorption range, including
for non-visible light (many space-based sensors operate be-
yond even the infrared and ultraviolet ranges). So do radar
systems. Black coatings that can go on any surface, survive
extreme conditions, and which reflect almost no light are
rather useful in converting almost any aircraft into a stealth
vehicle. But let’s put those unhappy thoughts aside for the
moment and think instead of art. As Sir Anish Kapoor said
when discussing his plans for VantaBlack, “Imagine a space
that’s so dark that as you walk in you lose all sense of where
you are, what you are, and especially all sense of time.”
And that’s plenty scary on its own, wouldn’t you say?
NANOTECHNOLOGY