Both airplane wings and helicopter rotor blades are subject to one problem – they can both ice up. Although de-icing solutions can be applied when aircraft are on the ground, that doesn't stop ice from eventually forming once they're in the air. That's why scientists at Texas' Rice University have developed a new graphene-based coating that continuously melts ice by conducting an electrical current.
Led by Prof. James Tour, the researchers combined an epoxy with what are known as graphene nanoribbons. These are made by "unzipping" carbon nanotubes along one side – carbon nanotubes being nanoscale tubes made of graphene. The resulting nanoribbons are basically flat rectangular sheets of graphene, which present more face-to-face surface area than they did when in nanotube form.
Although the ribbons make up only 5 percent of the epoxy/graphene composite, their electrical conductivity is sufficient to allow a current to pass through a coating of the material. Even using a relatively small voltage, that coating delivers enough electrothermal heat to melt ice.
In lab tests, the leading edge of a rotor blade was coated with the composite, after which a metal protective sleeve was attached over the coating. By applying an electrical current, the scientists were able to heat the composite to a temperature of over 200º F (93º C). This in turn heated the sleeve to the point that it could melt away a 1 cm (0.4 in)-thick layer of ice. The rotor blade wasn't moving at the time, and was in a -4º F (-20º C) environment.
Along with helping to make cold-weather flight safer, the technology could also lessen the need for environmentally-unfriendly de-icing solutions, plus it could help protect aircraft against lightning strikes by providing extra electromagnetic shielding.
A paper on the research was recently published in the journal ACS Applied Materials and Interfaces.
Source: Rice University