A protective coating of carbon nanotubes may help the Pentagon field warplanes and missiles that can survive the intense heat generated at five times the speed of sound.
Researchers from Florida State University’s High-Performance Materials Institute, with funding from the U.S. Air Force, discovered that soaking sheets of carbon nanotubes in phenol-based resin increases their ability to disperse heat by about one-sixth, allowing a thinner sheet to do the job.
Carbon nanotubes have shown potential in a wide variety of applications in recent years, everything from space elevators to drug delivery. The flexible molecules, just a billionth of a meter wide, are 100 times stronger than steel but only 16 percent of the weight. The sheets also both disperse heat and insulate well.“Carbon nanotubes have magnitudes higher in-plane thermal conductivity than carbon fiber,” researcher Ayou Hao explained to Defense One in an email. “Once heat reaches the carbon nanotube thermal protection layer surface, it is quickly dispatched.”
Of course, carbon nanotubes don’t exist in nature. They have to be made. The creation of new materials at the nanoscale is, technically, nanotechnology, which sounds exotic and expensive. But manufacturing processes in recent years have brought down the cost of producing carbon nanotube sheets. Multiple fabrication methods exist today, including the use of small electrical explosions called arc flashes, lasers, etc.
“Regarding accessibility of the raw materials, the price is lower and large sheets and yarns of carbon nanotube materials are available commercially,” meaning that they are cheaper than a few years ago, said Hao. But, she added, “seeking more affordable manufacturing approaches” remains a goal.