Nano-coating makes coaxial cables lighter

Rice University scientists claim to have developed a way of coating common coaxial cables with a nanotube-based outer conductor that is claimed to make them 50% lighter.

Professor Matteo Pasquali says his coating could replace the tin-coated copper braid that currently transmits the signal and shields cables from electromagnetic interference. The metal braid is the heaviest component in modern coaxial data cables.

Replacing this outer conductor with Prof Pasquali’s flexible, high-performance coating could benefit airplanes and spacecraft, in which the weight and strength of data-carrying cables are significant factors in performance.

Rice research scientist Francesca Mirri made three versions of the new cable by varying the carbon-nanotube thickness of the coating. Mirri found that the thickest, about 90µm met military-grade standards for shielding and was also the most robust; it handled 10,000 bending cycles with no detrimental effect on the cable performance.

"Current coaxial cables have to use a thick metal braid to meet the mechanical requirements and appropriate conductance," Mirri said. "Our cable meets military standards, but we're able to supply the strength and flexibility without the bulk."

Coaxial cables consist of four elements: a conductive copper core, an electrically insulating polymer sheath, an outer conductor and a polymer jacket. The Rice lab replaced only the outer conductor by coating sheathed cores with a solution of carbon nanotubes in chlorosulphonic acid.

Compared with earlier attempts to use carbon nanotubes in cables, this method yields a more uniform conductor and has higher throughput, Pasquali said. "This is one of the few cases where you can have your cake and eat it, too," he said. "We obtained better processing and improved performance."

Mirri claimed that replacing the braided metal conductor with the nanotube coating eliminated 97% of the component's mass.

The lab is now working on a method to scale up production and is drawing on its experience in producing high-performance nanotube-based fibres.

"It's a very similar process," Mirri said. "We just need to substitute the exit of the fibre extrusion setup with a wire-coating die. These are high-throughput processes currently used in the polymer industry to make a lot of commercial products. We are currently working on a Small Business Innovation Research project with the Air Force Research Laboratory to see how far we can take it."

Author
Tom Austin-Morgan

This material is protected by MA Business copyright
See Terms and Conditions.
One-off usage is permitted but bulk copying is not.
For multiple copies contact the sales team.

 

Supporting Information
Do you have any comments about this article?
Name
 
Email
 
Comments
 

Your comments/feedback may be edited prior to publishing. Not all entries will be published.
Please view our Terms and Conditions before leaving a comment.

© MA Business Ltd (a Mark Allen Group Company) 2020