Graphene coating designed to keep wings ice-free
Conductive composite material heats aircraft surfaces to simplify ice removal.0
“Applying this composite to wings could save time and money at airports where the glycol-based chemicals now used to de-ice aircraft are also an environmental concern,” said James Tour, professor of Materials Science and NanoEngineering at Rice University.
The highly conductive nanoribbons used in the composite were commercially produced by unzipping nanotubes, a process also invented at Rice University. Rather than making large sheets of the expensive material, the lab determined years ago that nanoribbons in composites interconnect and conduct electricity across the material with much lower loadings than traditionally needed. In Rice’s lab tests, nanoribbons made up no more than 5 percent of the overall composite.
To test the coating, the research team spread a thin coat of the graphene composite on a segment of a helicopter rotor blade and then replaced the thermally conductive nickel abrasion sleeve used on blade’s leading edge. Applying a small voltage to the coating delivered electrothermal heat – called Joule heating – to the surface. In tests, the coating melted centimeter-thick ice from a static rotor blade in a -4°F environment. The researchers were able to heat the composite to more than 200°F and reported that it remained robust up to nearly 600°F.
However, Tour said the composite wouldn’t need to reach those temperatures. For wings or blades in motion, he says, the thin layer of water that forms first between the heated composite and the surface should be enough to loosen ice and allow it to fall off without having to melt completely. In addition, Tour said the coating might also help protect aircraft from lightning strikes and provide an extra layer of electromagnetic shielding.