Large sheets of Carbon nanotubes produced

Nanocomp Technologies of Concord, is producing sheets of carbon nanotubes that measure three feet by six feet and promising slabs 100 square feet in area as soon as this summer. The first applications will probably be as electrical conductors in planes and satellites to replace copper wire and save weight. Saving weight would save fuel.

UPDATE: As of January 2009,the size of their carbon nanotube sheets was only increased to 4 feet by 8 feet.

Nanocomp’s materials possess a unique combination of high strength-to-weight ratio, electrical and thermal conductivity, as well as flame resistance that exceeds those of many other advanced materials by orders of magnitude. The resulting material can be a valuable addition to such applications such as electromagnetic interference (EMI) shielding, electrical conductors, thermal dissipation solutions, lightning protection and advanced structural composites. Full scale production in 2012 is expected. One of many application of interests to futurists would be superior solar sails A carbon nanotube sail could reach 4% of the speed of light by just making a close flyby slingshot around the sun. Such a perfected carbon nanotube sail would take fibers that were meters in length and not millimeters. However, the progress with large sheets of carbon nanotubes combined with being able to scale up from excellent millimeter gauge strength fibers could get us very close to that kind of performance. A solar sail would not be able to take that much cargo (think small robotic probes), but it would enable a radical improvement over the capabilities of chemical and ion rockets.

18 square foot sheets of carbon nanotubes have been made, with sheets hundreds of square feet in size promised by the summer. Being able to make solar sails using carbon nanotubes with 0.1grams per square meter in weight (weight would include all cargo and gear and structure, if the carbon nanotubes were doped for better conductance) would enable a swing by the sun within 4 solar radii to drive a solar sail up to 4% of the speed of light. Enabling high speed probes. Obviously a lot of work ahead for that goal but encouraging progress none the less.

The baseline solar sail design for an interstellar probe (ISP) mission to the near-interstellar medium assumes an areal density of 1g/m**2 (including film and structure), and a diameter of ~410 m. Missions to the stars will require very large sails with areal densities approaching 0.1 g/m**2.

Current solar sail material

There has been some theoretical speculation about using molecular manufacturing techniques to create advanced, strong, hyper-light sail material, based on nanotube mesh weaves, where the weave “spaces” are less than ½ the wavelength of light impinging on the sail. While such materials have as-of-yet only been produced in laboratory conditions, and the means for manufacturing such material on an industrial scale are not yet available, such materials could weigh less than 0.1 g/m² making them lighter than any current sail material by a factor of at least 30. For comparison, 5 micrometre thick Mylar sail material weighs 7 g/m², aluminized Kapton films weighs up to 12 g/m², and Energy Science Laboratories’ new carbon fiber material weighs in at 3g/m².

The tensile strength of the mat ranges from 200 to 500 megapascals—a measure of how tough it is to break. A sheet of aluminum of equivalent thickness, for comparison, has a strength of 500 megapascals. If Nanocomp takes further steps to align the nanotubes, the strength jumps to 1,200 megapascals. The sheets, which the company can produce on its single machine at a rate of one per day, are composed of a series of nanotubes each about a millimeter long, overlapping each other randomly to form a thin mat.

CNT fiber 6 gigapascals and short 1-2 millimeter gauge strength tubes have up to 9 gigapascals of strength.

Team Deltax is among many trying to make high strength macro scale fiber Some are trying to make carbon fibers from forests of fibers on silicon wafer.

There were several announcements from the end of 2007 about breakthroughs in carbon nanotube strength but so far it has been limited to gage length fibers (1-2 millimeters)

Single-walled carbon nanotubes are among the strongest materials known
and exhibit remarkably high stiffness—about 1 terapascal, and 1.2 gigapascal for high-carbon steel.
Theoretically carbon nanotubes can have tensile strengths beyond 120 GPa, in practice the highest tensile strength ever observed in a
single-walled tube is 52 GPa, and such tubes averaged breaking between 30 and 50 GPa. The trouble has been keeping this strength up to macrolength fibers/ropes and sheets.

Kevlar has a tensile strength of 2.6-4.1 GPa
Quartz fiber can reach upwards of 20 GPa.
PBO 5.2-5.8 GPa
Spectra 1000 2.57 Gpa
Carbon fiber 3.5 GPa (tens of thousands of tons of carbon fiber are produced each year)
M5 fiber has been reported at 3-6 GPa of tensile strength but was supposed to reach a conservative 8.5 GPa and a target of 9.5 GPa of tensile strength There have not been many reports since 2004-2005 on the progress of the M5 fiber. It seems they are still working at laboratory quantity and scale.

Los Alamos had talked about making tubes that were several centimeters in length and spinning them into fibers that had 50 GPa and was called Superthread However, there has been no news since 2006 about this development.

Antoinette says Nanocomp’s technical achievement was to figure out a way to maintain the catalyst particle at the desired size and hold it stable long enough for the nanotube to grow to millimeter length. A computer controlling about 30 different parameters in the process—including temperature, temperature gradient, gas flow rates, and the chemistry of the mix—allows the builders to control the properties of the tubes. One setting gives them single-walled tubes, and another gives multi-walled versions, with one cylinder inside another, which provide different properties.

Adding conductive cables made of his nanotubes to the bodies of airplanes would channel the energy from lightning strikes around sensitive electronic equipment without adding much weight. And running electricity through them on the ground could heat them up and de-ice the aircraft.

It’s the light weight of carbon nanotube wires—only about 20 percent of the weight of the same volume of copper wire—that could make them especially attractive for the aerospace industry. “1850s copper wire is still the conductor of all our satellites, all our aircraft,” Antoinette says. If using nanotubes could cut the weight of two tons of copper wire in a 747 in half, he says, “you’re talking literally millions of dollars of savings in fuel costs” over the life of an airplane.

Nanocomp has already been qualified as a vendor by Boeing, Lockheed Martin, and Northrop Grumman. The company is shipping evaluation quantities of its material to them and others for testing in various uses. Once Nanocomp gets to 100-square-foot sheets, the company will decide whether it wants to continue to scale up the size or to build more machines to ramp up production. Antoinette expects to have a pilot plant running by 2010, with full-scale production by 2012.

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