| Résumé : |
The ability of materials to conduct electricity is affected by temperature. When the temperature approaches absolute zero (–273°C), many materials—from metals to ceramics to carbon nanotubes—conduct electricity with no resistance, thus becoming superconductors. In these materials, electrons pair up and travel effortlessly, avoiding interactions with single electrons and other obstacles in circuits. Superconductors are attractive because they can be used to generate large magnetic fields, and superconducting magnets find use in everything from magnetic resonance imaging (MRI) machines to the detectors in supercolliders. The key challenge to their widespread use is the need to maintain the temperature at approximately –173°C (100 Kelvin) or lower, depending on the material. If a room-temperature superconductor could be identified, levitating trains and hoverboards could be possible.
For many superconducting applications, coatings play a vital role. Electrically insulating coatings have been commonly used on superconducting wires. Newer insulating coatings, such as the ultra-thin polyimide coatings developed by scientists at the RIKEN Center for Life Science Technologies and Chiba University,1 can be as thin as 4 mm. This is more than 10 times thinner than the conventional insulation used for high-temperature superconducting wires. Wires with the new coating have a cross-section containing just 10% insulation, a fivefold reduction of conventional superconducting wires, and they exhibit double the magnetic strength. Reducing the ratio of insulation to conductor in the wire allows for more compact superconducting coils for use in next-generation medical and scientific devices. |
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Coatings participate in the superconducting realm in COATINGS TECH, Vol. 17, N° 2 (02/2020)
