Tag Archives: CNT tthin film

Taking the baking out of aircraft manufacture

It seems that ovens are an essential piece of equipment when manufacturing aircraft parts but that may change if research from MIT (Massachusetts Institute of Technology) proves successful. An April 14, 2015 news item on ScienceDaily describes the current process and the MIT research,

Composite materials used in aircraft wings and fuselages are typically manufactured in large, industrial-sized ovens: Multiple polymer layers are blasted with temperatures up to 750 degrees Fahrenheit, and solidified to form a solid, resilient material. Using this approach, considerable energy is required first to heat the oven, then the gas around it, and finally the actual composite.

Aerospace engineers at MIT have now 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.

The new “out-of-oven” approach may offer a more direct, energy-saving method for manufacturing virtually any industrial composite, says Brian L. Wardle, an associate professor of aeronautics and astronautics at MIT.

“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,” Wardle says. “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 says the carbon nanotube film is also incredibly lightweight: After it has fused the underlying polymer layers, the film itself — a fraction of a human hair’s diameter — meshes with the composite, adding negligible weight.

An April 14, 2015 MIT news release, which originated the news item, describes the origins of the team’s latest research, the findings, and the implications,

Carbon nanotube deicers

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.

The group first developed a technique to create a film of aligned carbon nanotubes composed of tiny tubes of crystalline carbon, standing upright like trees in a forest. The researchers used a rod to roll the “forest” flat, creating a dense film of aligned carbon nanotubes.

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?

How hot can you go?

In initial experiments, the researchers investigated the film’s potential to fuse two types of aerospace-grade composite typically used in aircraft wings and fuselages. Normally the material, composed of about 16 layers, is solidified, or cross-linked, in a high-temperature industrial oven.

The researchers manufactured a CNT film about the size of a Post-It note, and placed the film over a square of Cycom 5320-1. They connected electrodes to the film, then applied a current to heat both the film and the underlying polymer in the Cycom composite layers.

The team measured the energy required to solidify, or cross-link, the polymer and carbon fiber layers, finding that the CNT film used one-hundredth the electricity required for traditional oven-based methods to cure the composite. Both methods generated composites with similar properties, such as cross-linking density.

Wardle says the results pushed the group to test the CNT film further: As different composites require different temperatures in order to fuse, the researchers looked to see whether the CNT film could, quite literally, take the heat.

“At some point, heaters fry out,” Wardle says. “They oxidize, or have different ways in which they fail. What we wanted to see was how hot could this material go.”

To do this, the group tested the film’s ability to generate higher and higher temperatures, and found it topped out at over 1,000 F. In comparison, some of the highest-temperature aerospace polymers require temperatures up to 750 F in order to solidify.

“We can process at those temperatures, which means there’s no composite we can’t process,” Wardle says. “This really opens up all polymeric materials to this technology.”

The team is working with industrial partners to find ways to scale up the technology to manufacture composites large enough to make airplane fuselages and wings.

“There needs to be some thought given to electroding, and how you’re going to actually make the electrical contact efficiently over very large areas,” Wardle says. “You’d need much less power than you are currently putting into your oven. I don’t think it’s a challenge, but it has to be done.”

Gregory Odegard, a professor of computational mechanics at Michigan Technological University, says the group’s carbon nanotube film may go toward improving the quality and efficiency of fabrication processes for large composites, such as wings on commercial aircraft. The new technique may also open the door to smaller firms that lack access to large industrial ovens.

“Smaller companies that want to fabricate composite parts may be able to do so without investing in large ovens or outsourcing,” says Odegard, who was not involved in the research. “This could lead to more innovation in the composites sector, and perhaps improvements in the performance and usage of composite materials.”

It can be interesting to find out who funds the research (from the news release),

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.

Here’s a link to and citation for the research paper,

Impact of carbon nanotube length on electron transport in aligned carbon nanotube networks by Jeonyoon Lee, Itai Y. Stein, Mackenzie E. Devoe, Diana J. Lewis, Noa Lachman, Seth S. Kessler, Samuel T. Buschhorn, and Brian L. Wardle. Appl. Phys. Lett. 106, 053110 (2015); http://dx.doi.org/10.1063/1.4907608

This paper is behind a paywall.

Buckypaper technology in Florida (US) receives $!.4M grant

Just after suggesting (as per my Nov. 26, 2013 posting) that Florida is quietly becoming a center for nanotechnology efforts in the US, there’s a $1.4M funding announcement for Florida State University’s High-Performance Materials Institute (HPMI. From the Nov. 27, 2013 news item on Nanowerk,

Florida State researchers have been awarded more than $1.4 million from the National Science Foundation to develop a system that will produce large amounts of a state-of-the-art material made from carbon nanotubes that researchers believe could transform everything from the way airplanes are built to how prosthetic limbs fit the human body.

“The goal is clear — to show industry the ability to use this in large-scale quantities,” said Richard Liang, director of FSU’s High-Performance Materials Institute (HPMI) and a professor for the FAMU-FSU College of Engineering. “We’re looking at a more efficient, cost effective way to do this.”

The Nov. 26, 2013 Florida State University (FSU) news release (also on EurekAlert), which originated the news item, provides greater detail about buckypaper, the team’s research work, and the team’s hopes for this grant,

The material, buckypaper, is a feather-light sheet made of carbon nanotubes that is being tested in electronics, energy, medicine, space and transportation.  The aviation industry, for example, is doing tests with buckypaper, and it’s projected that it could replace metal shielding in the Boeing 787, currently made up of 60 miles of cable.

Engineers believe that replacing the cable with buckypaper could reduce the weight of the Boeing 787 by as much as 25 percent.

Florida State researchers have been engaged in other projects with buckypaper as well, including the use of the material in creating more advanced and comfortable prosthetic sockets for amputee patients and multifunctional lightweight composites for aerospace applications.

As revolutionary as buckypaper technology is, a major hurdle for its future use is that it can take two or more hours and can cost as much as $500 to make just a small 7-inch by 7-inch piece.  Companies like Boeing need large amounts of it to use on an aircraft.

However, the current process is neither fast nor cheap.

So, Liang will spend the next four years developing a process to produce large-scale amounts of buckypaper. The process and materials would then be patented and marketed to meet the demands of the industrial partners.

Liang will be joined on the project by Arda Vanli, an HPMI researcher and an assistant professor in the Department of Industrial and Manufacturing Engineering, as well as researchers from Georgia Institute of Technology.

The US National Science Foundation (NSF) webpage listing the award describes the specific research being undertaken and introduces the term ‘Bucky-tapes’,

Award Abstract #1344672
SNM: Roll-to-Roll Manufacturing of High Quality Bucky-tape with Aligned and Crosslinked Carbon Nanotubes Through In-line Sensing and Control

Carbon nanotubes (CNTs) demonstrate amazing properties; however, currently only a fraction of these properties can be transferred into products that can be used by engineers and consumers. To effectively transfer CNTs? properties into useful products requires a method to efficiently align and covalently interconnect the CNTs into tailored architectures at the nanoscale. This project will establish the fundamental understanding and foundation for using CNTs to make thin sheet materials, called Bucky-tapes, which can be rapidly produced in roll form and scaled-up for industrial applications. The proposed method will use a modified die-casting manufacturing process utilizing the self-repelling effects of selected flow media. In-situ ultra-violet (UV) reaction chemistry can covalently interconnect the CNTs rapidly to improve the load transfer and thermal and electronic transport properties of CNT networks. In-line multi-stage stretching of the web could orient the randomly dispersed interconnected CNT networks into specific patterns to provide greater strength and optimized transport properties. In-line Raman spectra monitoring and multistage process models will provide affordable, closed loop quality control and variation reduction methods for a high quality consistent nanomanufacturing process. A prototype will be built to demonstrate the continuous roll-to-roll process for manufacturing strong Bucky-tapes with high electrical and thermal conductivity, and low manufacturing cost.

This project can transform CNT thin films networks from a lab-scale demonstration material into commercially viable products with superior properties potentially surpassing the state-of-the-art carbon fiber material. The continuous Bucky-tapes can lead to new materials applications in aerospace, electronics, energy, medicine, and transportation. For example, continuous Bucky-tape could replace metal shielding of 60 miles of cables in the Boeing 787 and reduce cable weight by 25%. The education and outreach plan will expose especially under-represented students to molecular design, nanomanufacturing process development and quality control, structure-property relationship studies. Application oriented materials-by-design and nanomanufacturing process development will motivate students into nanotechnology, manufacturing and new materials development.

I had mentioned this team’s work on buckypaper (or are they now calling it Bucky-tape?) in an Oct. 4, 2011 posting which features a video about buckypaper and in which I noted the possible applications for buckypaper closely mirror those for CNC (cellulose nanocrystals) or, as it’s also known,  NCC (nanocrystalline cellulose).

You can check out Florida State University’s High Performance Materials Institute here.