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Aug. 3, 2004 – A window on military aircraft, whether it is a canopy on a fighter jet or the covering on an infrared sensor, faces a far different environment from its counterpart on land. It must be exceptionally sturdy to withstand being battered by debris at high velocities, yet remain transparent to allow the pilot to see out, or the infrared signal to reach in.
The Department of Defense, Air Force and Navy hope to eliminate that and similar tradeoffs using nanomaterials.
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The agencies funded three separate programs recently to develop various nanomaterials to improve aircraft and missile windows. The companies expect to convert the knowledge and skills they gain on their respective military projects into products for broader civilian markets.
Nanomaterials offer one or more properties that don’t exist in bulk material, whether that is increased strength, novel optical characteristics or magnetism, said Richard Schorr, president of MetaMateria Partners in Columbus, Ohio.
MetaMateria announced in June that it received $750,000 from the Navy to make windows for infrared sensors on missiles and aircraft using yttria nanoparticles. The funding will allow MetaMateria to refine its processes to manufacture not just nanopowders with special attributes but parts and coatings.
“How do you take nanoparticles and consolidate them into something?” Schorr said. “You have to learn how to do that, to convert them into solids.”
Last year, MetaMateria proved to the Navy that it could engineer and manipulate yttria nanoparticles into high concentrations under a Phase I Small Business Innovation Research award. Infrared light passes through yttria, making it an attractive window material for infrared sensors on guided missiles.
But yttria is also weak. Windows made of conventional yttria tend to crack in flight conditions. MetaMateria is trying to strengthen the windows using a process that packs nanograins of yttria as closely as possible.
“What we’re trying to do is get individual discrete nanoparticles to accumulate in some kind of solid,” he said. “We should get about 60-percent density,” or twice the density of nanopowder pressed onto a surface. “We realized early on that what the Navy wanted was not a powder, but a window.”
MetaMateria, a subsidiary of NanoDynamics Inc., is in discussions with Raytheon and two other companies to supply windows for military products, Schorr said. He expects the process also will serve as a cost-effective method for coatings on infrared store scanners and other applications.
Crosslink Polymer Research in St. Louis, Mo., is also looking at nanomaterials as a possible solution to another problem naval aircraft face.
In June, the U.S. House of Representatives approved a $5 million Defense appropriation for the Nano-Composite Hard-Coat for an Aircraft Canopies project.
The goal is to extend the lifetime of canopies on fighter jets. Canopies are the clear domes that give pilots maximum visibility.
Crosslink is partnering with Southwest Missouri State University, Brewer Science in Rolla, Mo., and a division of Boeing Co.
Their goal is to develop coatings for aircraft that are durable, transparent and capable of dispersing the electrostatic charge that builds up on plastic canopies, according to Don Landy, Crosslink’s vice president of operations.
“We want to build a system that can be self-dissipative,” Landy said, “from the window to the plane to the ground.”
They propose developing a two-layered protective coating that can be stripped off the canopy and replaced when the canopy’s visibility is compromised. Today’s coatings require more than a half-dozen layers, Landy said.
Several materials, including nanocrystals and carbon nanotubes, may offer the needed properties. Crosslink intends to look for markets outside defense if they successfully develop a dissipative technology. Charge buildup interferes with some MEMS fabrication processes, for instance, making fabs a possible customer.
Eikos Inc. in Franklin, Mass., is working with the Air Force on a carbon nanotube-based application for canopies. The Air Force Research Laboratory awarded Eikos an $860,000 contract in May to develop transparent conductive polymers for canopies.
Eikos Chief Executive Joe Piche said the company’s ultimate goal is to get its carbon nanotube products into consumer markets such as flat panel displays and solar cells.