Principal result is that no dramatic difference in sample yield or composition was noted between normal gravity and 2.2 and 5s long microgravity runs. An arc reactor was operated in the drop towers at the NASA Glenn Research Center. To study the effect of buoyancy on the arc process, a miniature carbon arc apparatus was designed and developed to synthesize SWNTs in a microgravity environment substantially free from buoyant convective flows. High temperatures inside the plasma of a carbon arc generate strong buoyancy driven convection which has an effect on the growth and morphology of the single-walled carbon nanotubes (SWNTs). It was determined that the synthesis of carbon nanotubes by the arc-in-water method is strongly affected by gravity. In this paper, we report on the synthesis of carbon nanotubes by means of the arc-in-water method under microgravity and normal gravity conditions. The "arc-in-liquid" method is a simple and inexpensive technique for the synthesis of carbon nanotubes and related nano-materials. Longer lengths of carbon nanotubes open up possibilities for spinning super strong fibers that can be used for a variety of purposes needing strength, lightness, and conductivity (Zhang et al. Physicists have theorized, but not proven, that in microgravity the elimination of convection could allow for the successful production of single-walled carbon nanotubes longer than one centimeter (Alford, Mason, and Feikema 2001). Long single strands could be then interwowen into even stronger cables. Short strands are very difficult to connect with the same strength. Preferably tens of thousands of kilometers for space elevator. Many kilometer lengths of single-walled carbon nanotubes are required. 3 cm length is common and record is 55 cm. Only very short carbon nanotubes can be currently made. They consist of tiny threads of pure carbon nanotubes compressed into a fiber and lose the wondrous properties of pure nanotubes. You might hear announcements that nanotubes many feet long have been constructed, but those materials are actually composites. Extremely difficult to manufacture beyond a centimeter or so. It is difficult to produce sheets larger than a postage stamp. The slightest impurity or imperfection at the molecular level can ruin its miraculous physical properties. At the moment, it is exceedingly difficult to product large quantities of pure graphene. If you built the suspension for the Brooklyn Bridge out of carbon nanotubes, the bridge would look like it was floating in midair. They are practically unbreakable and nearly invisible. Carbon nanotubes are sheets of graphene rolled into long tunes. Overview of commercial microgravity applications.Ĭarbon nanotubes are the toughest material known to science - two hundred times stronger than stell and stronger even than diamonds. Introduction to in-space manufacturing and in-space economy. The tubes are 1-2nm in diameter with lengths of 5-30 microns.Factories in space.Core material pieces (20-40% nanotubes)Ġ6-0506: Carbon nanotubes, multi-walled, ground core material Ġ6-0508: Carbon nanotubes, single-walled/double-walled, 90%.The chemical composition is 100% carbon, with no metal impurities.Ġ6-0504: Carbon nanotubes, multi-walled, as produced cathode deposit Ġ6-0505: Carbon nanotubes, multi-walled, core material The tubes have a diameter distribution of 2-50 nm, and a typical length of >2 microns (straight tubes). Contains 55-65 wt% nanotubes and 35-45wt% graphite nanoparticles.Typical metal content is 2 microns) (55-65wt% nanotubes) The diameter of the MWNTs may range from 50-100 nm with tube lengths from 90% nanotubes) 1) SWNTs may have a diameter of about one nanometer. The forms are dependent upon how the cylinders are wrapped.ĬNTs may have many structures of different length, thickness, and number of layers, forming single-walled nanotubes (SWNTs) and multi-walled (MWNTs). There are three different forms of single-walled carbon nanotubes (SWCNTs) such as armchair, chiral, and zigzag. Similar to fullerenes, they have a honeycombed, net-like structure with six-membered sp²-hybridized carbon rings. CNTs are small tubular structures of two-dimensional graphene sheets, rolled into a cylindrical form. The first fundamental studies on CNTs were reported by Iijima in the early nineties. It is hard to imagine nanotechnology and materials science without carbon nanotubes (CNTs) and their outstanding physical and chemical properties.
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