Monday, February 1, 2016

Rice-University-Graphene-Composite-Melt-Ice-on-Helicopters - Charles D'Alberto

Abstract Image
A conductive composite of graphene nanoribbon (GNR) stacks and epoxy is fabricated. The epoxy is filled with the GNR stacks, which serve as a conductive additive. The GNR stacks are on average 30 nm thick, 250 nm wide, and 30 μm long. The GNR-filled epoxy composite exhibits a conductivity >100 S/m at 5 wt % GNR content. This permits application of the GNR-epoxy composite for deicing of surfaces through Joule (voltage-induced) heating generated by the voltage across the composite. A power density of 0.5 W/cm2 was delivered to remove ∼1 cm-thick (14 g) monolith of ice from a static helicopter rotor blade surface in a −20 °C environment.

Last week, more than 10,000 flights across the east coast of the United States were canceled due to the onslaught brought on by winter storm Jonas. Planes cannot fly if the wings are covered in ice. However, a team of researchers may have a solution for future storms.
Rice University researchers have developed a graphene composite that has shown it can melt ice on a helicopter blade. During a study, led by graduate student Abdul-Rahman Raji, researchers embedded graphene nanoribbon (GNR)-infused epoxy resin in a section of a helicopter blade to test its ability to remove ice.
The team was able to use the composite to melt centimeter-thick ice from the blade in a -4 F environment. When a small voltage was applied, the composite coating delivered electrothermal heat – called Joule heating – to the surface of the blade, which successfully melted the ice. During the tests, the team was able to heat the composite to more than 200 F, and also remained robust in temperatures up to nearly 600 F.
As Rice explained in a January 25 press release, the highly conductive nanoribbons are produced commercially by unzipping nanotubes, a process also invented at the university. Rather than trying to produce large sheets of expensive graphene, the lab determined years ago that nanoribbons in composites would interconnect and conduct electricity across the material with much lower loadings than traditionally needed.
Chemist James Tour says the new GNR-epoxy composite can be applied to more than just helicopter blades, adding it can be a cost-effective, real-time de-icer for aircraft, wind turbines, transmission lines and other surfaces exposed to turbulent, cold weather.
“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,” Tour said.