Aerospace engineers at MIT have developed a carbon nanotube (CNT) film that can heat and solidify a composite without the need for massive ovens. When connected to an electrical power source, and wrapped over a multilayer polymer composite, the heated film stimulates the polymer to solidify.
The group tested the film on a common carbon fiber material used in aircraft components, and found that the film created a composite as strong as that manufactured in conventional ovens — while using only 1 percent of the energy.
Composite materials used in aircraft wings and fuselages are typically manufactured in large, industrial-sized ovens and use large amounts of energy. “Typically, if you’re going to cook a fuselage for an Airbus A350 or Boeing 787, you’ve got about a four-story oven that’s tens of millions of dollars in infrastructure that you don’t need,” says Brian L. Wardle, an associate professor of aeronautics and astronautics at MIT. “Our technique puts the heat where it is needed, in direct contact with the part being assembled. Think of it as a self-heating pizza. … Instead of an oven, you just plug the pizza into the wall and it cooks itself.”
Wardle and his colleagues have experimented with CNT films in recent years, mainly for deicing airplane wings. The team recognized that in addition to their negligible weight, carbon nanotubes heat efficiently when exposed to an electric current. In experiments, Wardle and his team integrated the film into airplane wings via conventional, oven-based curing methods, showing that when voltage was applied, the film generated heat, preventing ice from forming. The deicing tests inspired a question: If the CNT film could generate heat, why not use it to make the composite itself? The group tested the film’s ability to generate higher and higher temperatures, and found it topped out at over 1,000 F, which Wardle says means there’s no composite they can’t process with this method.
This research was funded in part by Airbus Group, Boeing, Embraer, Lockheed Martin, Saab AB, TohoTenax, ANSYS Inc., the Air Force Research Laboratory at Wright-Patterson Air Force Base, and the U.S. Army Research Office.
See more of Composite Manufacturing’s coverage on out-of-oven and out-of-autoclave applications: No Autoclave, No Oven, No Problem!