Teflon-coated frying pans may scratch easily, but a souped-up version, a
nanomaterial 10,000 times more durable than the ordinary non-stick stuff, is
headed for the space station to see if it could someday coat the mechanical
moving parts of spacecraft.
But first it must prove it can survive ultraviolet radiation, atomic
oxygen, extreme temperatures and other space hazards, after
blasting off Monday aboard the space shuttle Atlantis on a course for the
International Space Station (ISS).
Astronauts intend to install the material outside the space station
during one of the mission's planned spacewalks.
The super Teflon could theoretically slide across a surface for more
than 62,000 miles (100,000 km) before wearing away, compared to ordinary Teflon
that would last just a mile or so. Researchers added fluoride-coated alumina
nanoparticles that helped boost the material's strength and durability, even as
it retained most of the Teflon's non-stick slipperiness.
"These are low wear, low friction materials that work well in
vacuum, and we want to know if they work well in space," said Greg Sawyer,
a mechanical and aerospace engineer at the University of Florida. He leads a
multi-university effort backed by the U.S. Air Force that designed a whole
range of nanocomposite materials for space trials aboard the space station.
Better space-age materials
Sawyer worked with his former mentors at the Rensselaer Polytechnic
Institute (RPI) in New York to develop nanocomposite materials for many
different space applications. Super Teflon's durability and non-stick character
would make it easier for moving parts within spacecraft to move, and require
less energy due to less resistance from friction.
Rensselaer researchers also built conductive nanocomposites in
collaboration with the U.S. Department of Energy National Renewable Energy
Laboratory. One material consists of a tough polymer filled with carbon
nanotubes, or tiny cylinders made of carbon that can conduct electricity.
The second conductive material involves liquid crystalline polymers, which can resist
fires and many industrial chemicals.
"Conductivity experiments look at how materials with conductivity
degrade over time," Sawyer told SPACE.com. "With PTSE [Teflon]
and those materials you're looking at how long they can provide adequate lubrication."
Another even more futuristic material comes in the form of so-called
"chameleon" coatings developed by the Air Force Research Laboratory
in Ohio. These adaptive materials can change their coating surfaces based on
how much friction or strength is needed.
Space trials are a go
Researchers ensured that all the nanocomposite materials flying aboard
the space shuttle Atlantis could first endure vacuum tests on Earth, as a bare
minimum requirement for surviving space trials. The team had to scramble in particular
to develop the conductive nanocomposites and ready it for launch in less than a
week.
"It was an exciting week and we weren't sure if the composites
would hold up to the rigorous testing imposed on them to determine if they
could even be launched into space," said Linda Schadler, a materials
engineer at RPI.
The Teflon study is part of a larger Materials International Space
Station Experiment - 7 (MISSE-7) that will expose materials on an outside test
bed, where the experiments face intense radiation and temperatures ranging from
-40 degrees to 140 degrees F (-40 degrees to 60 degrees C). Atomic oxygen
formed by ultraviolet rays splitting oxygen into single atoms also poses a
unique space hazard that can erode materials.
Sawyer designed a tribometer that can monitor the friction of the
materials such as the super Teflon. The material sample sits on a turntable
resembling a record, and stationary pin rests on top of the spinning sample.
"The sample spins under the pin, and during that we can record the
forces so we know how the material is behaving," Sawyer explained.
The experimental setup automatically sends data in real-time to the ISS
lab, which then forwards the info to university labs on Earth. After all the
work that went into getting their materials launched into space, researchers
plan on running the space trials for as long as possible.
Ultimately, MISSE experiments - which can be folded up like a suitcase –
can be collected by spacewalking astronauts to be packed up and returned to
Earth for waiting scientists.
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