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Graphene-Based Coating Could Act As a Real-time De-Icer For Aircraft (rice.edu)
hypnosec writes: Researchers have developed a graphene-based coating they have proved effective at melting ice from a helicopter blade, paving the way for a real-time de-icer. The thin coating of graphene nanoribbons in epoxy has been developed by researchers at Rice University. In their tests, researchers show the coating is capable of melting centimeter-thick ice from a static helicopter rotor blade in a -4 degree Fahrenheit environment. A small voltage was applied to the coating that delivered electrothermal heat — called Joule heating — to the surface, which melted the ice.
This has been done for ages. Electro-thermal deicing devices are commonly used on propellers.
My guess (TFA wasn't really clear in this respect) is that this is big news because we're talking about a coating. Deicing systems are usually bulky and used only on attack surfaces, which leads to some issues - on wings for example, if you don't set the right temperature ice will melt only to flow over the surface only to solidify again, harder, on a different place.
Deicing doesn't deal with snow, or, well, not of the light fluffy kind anyway. It's mean to remove thick layers of solid ice that can form on surfaces and significantly affect aircraft performance. The reason for deicing when you see snow on the aircraft is because you can never be sure that there isn't at least part ice underneath it. That's why they deice, just to be sure. I'm sure you'll rather sit through an unnecessary deice 1000 times over than die once when it was really needed. Ice is no joke and people absolutely have died in aircraft because of it.
That having been said, the way it works is that they have types of deicing fluid, each of which is certified for a particular temperature and protection time. So something like up to 15 minutes of protection at -10C, 10 minutes of protection at -15C and 5 minutes of protection at -20C. The aircraft then has that allowable time window to line up and get airborne. In flight, it'll then either have to fully rely on its own anti-icing equipment, or exit the icing conditions (which usually happens fairly quickly).
The reason why we don't use an aircraft's own anti-icing equipment on the ground is because it isn't very extensive. It usually only protects critical components (typically wing leading edges, engine inlets/props and the main cockpit windshield panels plus some external sensors such as pitot-static tubes and AoA vanes) and may not be even be available for performance-critical phases of flight (such as takeoff), because it robs too much power. Adding more anti-icing equipment would add lots of weight and cost, not to mention power demand. *That's* why we thoroughly de-ice on the ground. Give the whole aircraft a good rinse, takeoff and quickly leave the icing conditions.
An epoxy based coating on the leading edge of a helicopter rotor will be gone almost instantly. The blades are basically sand blasted on every takeoff and landing from the dirt and sand that gets kicked up by the rotors. That's why they have that metallic cap.
Also, the reason they don't heat the entire rotor blade now is because the electrical power requirements would be excessively high and it isn't necessary. The metallic ribbon heating elements they currently use are such a small contributor to the overall weight that it's almost negligible. The rest is thermal mass and insulation necessary to evenly distribute the energy across the anti-iced section of the blade and to protect the composite blade structure from the heat. Maybe, due to reduced thickness and uniform heat output, this new coating could be applied closer to the back side of the LE abrasion shield and be more resistant to foreign object damage being a continuous sheet, but I don't expect it to revolutionize the industry. It certainly won't grossly increase the range of application of aircraft anti-ice systems. Outside of rotors/propellers, aircraft generally use engine bleed air for anti-icing since that is readily available and the electric power needs to replace those systems would require much larger and heavier generators.
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