News Junkie
Carbon Nanotubes - Nova World's Strongest Materials
Sat Oct 15, 2016 3:32pm
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Youtube

You've got to be kidding, it's as if this stuff is begging to be made into a space elevator cable.

Watching this video makes me wonder if the growth process might be guided or molded through a thin molecular sieve? Molecular sieves can have pores as small as 1-2 nanometers, and be made of silica which has an extremely high melting temperature, making it potentially compatible with the production of carbon nanotube forests.

Like 3D-printing the material would be grown layer-by-layer on top of the sieve, building up a forest of nanotubes that is slowly drawn downward, through the pores in the molecular sieve, and rolled onto a spool, eventually reaching hundreds of (mega)meters in length.

And maybe the sieves could be arranged like tiles so that the diameter of the final nanotube cable can be scaled to millimeters or even centimeters thick depending on the application.

Hmmm...

    • An advantage of colonizing Mars ...Ken C, Mon Oct 31 9:31pm
      Less gravity and much thinner atmosphere so it would be easier to launch rockets.
    • Good for aircraft & spacecraft.DFM, Wed Oct 26 10:19pm
      Forget the "Space Elevator". It is NOT feasible. DFM
      • Why not?News Junkie, Mon Oct 31 4:02pm
        You are correct that it is not currently feasible. But progress is being made. Don't you think it is a bit premature to write it off?
        • Here are only a few of the problems. In order to be useful, it must carry cars up and down. At any reasonable estimate, the cars will be more massive than the stalk. Every time a load goes up, it... more
          • Then we accept the risk & mitigate itNews Junkie, Tue Nov 1 2:22pm
            I'll try to address each of your points without doing the full risk assessment that is done for anything that involves human safety. (1) In order to be useful, it must carry cars up and down. At any... more
            • Two millimeter cable is absurd.DFM, Thu Nov 3 7:47am
              More like two METER would be necessary for reliability and durability. A two millimeter cable could be destroyed instantly by an ordinary BIC lighter. Carbon nanotubes are strong, but NOT fire... more
              • Minor detailsNews Junkie, Thu Nov 3 2:09pm
                I'm sure some sort of thin cladding or surface treatment could protect the bundle of carbon nanotubes from ordinary environmental factors like lightning, or space radiation, or usage. The kinetic... more
                • No "thin cladding" is going to work.DFM, Sat Nov 5 10:05pm
                  There are no insulators good enough to protect that thin thread from a HUNDRED MILLION VOLT lightning strike at a reasonable weight. This thing is a colossal LIGHTNING ROD, and will be struck... more
                  • Then...News Junkie, Sun Nov 6 2:58pm
                    ... maybe it's possible to ensure the cable has exactly the same static charge as the air, so there is no potential for arcing to occur.
                    • Impossible.DFM, Mon Nov 7 5:34pm
                      The electrical potential of the air varies widely from place to place and changes by hundreds of millions of volts in microseconds when bolts happen. The line CANNOT possibly be kept at constant... more
                      • The payoff is worth the brainstormingNews Junkie, Mon Nov 7 7:44pm
                        Maybe the space elevator could be protected by an ionized column of air, created by a microwave laser beam projected upward from the ground. Maybe the conveyor-type space elevator could act as a... more
                        • and LESS reliable by introducing more possible failure modes. A Mach 26 ramjet could probably be built. Even if we could only get Mach 15 (remember, Mach 10 has already been achieved), that would... more
                          • Okay here's an ideaNews Junkie, Wed Nov 9 7:38pm
                            Maybe the space elevator itself could be used to "ground" the Earth's atmosphere. It bonds the sky to the ground by continuously drawing any excess charge and conducting it to the ground. To ensure... more
                            • We probably could not afford EVEN ONE.DFM, Wed Nov 9 9:34am
                              You are looking at costs of the a hundred trillion dollars, which is conservative. You need this massive and super-strong cable weighing at least a tonne per linear meter. At 35,786,000 meters in... more
            • CorrectionsNews Junkie, Tue Nov 1 3:10pm
              The safety margin would be 0.3. The cargo capacity of 48 GPa would support 150.796 kN of weight (15 tonnes) at ground level.
              • And...News Junkie, Tue Nov 1 3:19pm
                ... and if the system runs like a conveyor belt, with a continuous loop of carbon nanotube cable... ... and if the system can accelerate to, say 3000 kph above the atmosphere... ... then a trip to... more
                • More estimates !!!!News Junkie, Tue Nov 1 6:11pm
                  Regardless of altitude the cargo will always have a mass of about 15 tonnes. However, as altitude increases the weight of the cargo will decrease, relieving stress on the cable. To keep the stress on ... more
                  • CVT DriveNews Junkie, Wed Nov 2 10:56pm
                    So I envision a carbon nanotube continuous loop "conveyor belt" with a wheel at ground level and a wheel at geostationary. The wheel at ground level would be a tapered shaft, a "continuously variable ... more
                    • Speed of Sound in a Space ElevatorNews Junkie, Thu Nov 10 5:23pm
                      According to this article the speed of sound in graphene is 22.2 km/sec. Carbon nanotubes (CNTs) are like rolled up sheets of graphene. So if we assume CNTs have the same speed of sound, then it... more
    • Or maybe...News Junkie, Sat Oct 15 3:54pm
      Maybe the gases would pass through the molecular sieve and fuse to the tops of the nanotube forest below, and as the carbon nanotubes grow taller, the wafer would be slowly lowered. Or maybe it can... more
      • Growth of 55 cm long carbon nanotubesNews Junkie, Sat Oct 15 7:06pm
        Publication Lots of detail there. They mention a "moving furnace". I have to wonder why CNTs would stop growing at 1 cm or 55 cm, or any length. It seems like the only reason they don't have km-long... more
        • MATERIALS AND METHODSNews Junkie, Sun Oct 16 7:51am
          Synthesis of Ultralong CNTs with Different Conditions . The substrates were silicon slices (5-10 cm long, 0.5-1 cm wide, and 0.5 mm thick) with a 500 nm thick SiO2 layer. The growth of CNTs was... more
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