Protecting aircraft from lightning strikes probably isn't the first use of nanotechnology that springs to mind, but that's exactly what Fraunhofer researchers hope to achieve by combining carbon nanotubes with carbon fiber reinforced plastics (CFRPs).
The research at the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) centers on using the highly-conductive properties of carbon-nanotubes in plastic manufacturing.
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A new process has been developed where plasma is used to make the nanotubes homogeneous and better suited to bonding with the polymer.
“We spray the particles – i.e. the nanotubes – into this atmospheric plasma.” They immediately fall into the selected solvent, which can then be used to further process the polymer," says Dr. Jörg Ihde. "The whole procedure takes just a few seconds – a huge advantage over the old method, in which CNTs were generally prepared in an acid bath using a wet chemical process. That took several hours or days, required considerably more chemicals, and generated significantly more waste.
So what does this have to do with aircraft? It's not uncommon for planes to be hit by lightning, but modern aircraft are designed to cope with this. The key to this protection is maintaining a conductive exterior skin so that the current can pass from one side of the aircraft to another and exit without damaging the electrical systems or worse, like causing a fuel tank to explode.
That's OK for aluminum aircraft skins, but when less conductive carbon fiber reinforced plastics are introduced to lighten the design it gets a little trickier. One solution is to embed conductive fibers to carry the lightning current and the Fraunhofer work is an extension of this approach – because carbon nanotubes are highly conductive, CFRPs made using this new method will be easy to incorporate into lightning resistant aircraft designs.
The potential applications for the method also extend to increasing the heat dissipation properties of electrical components and reducing electromagnetic losses in electric motors.
“By mixing nanoparticles with plastics, we’ve been able to significantly enhance the material properties of the latter,” states Dr. Uwe Lommatzsch, project manager at the IFAM. To give just two examples, CNTs are being used to optimize the electrical conductivity of plastics, and their heat dissipation properties are likewise being improved by the addition of metal particles.
IFAM is showing the new tech at the K 2010 trade fair in Düsseldorf (October 27 - November 3, 2010).