Joint Base McGuire-Dix-Lakehurst, N.J. – A team of four engineers from the Naval Air Warfare Center Aircraft Division (NAWCAD) Lakehurst enhanced additive manufacturing (AM) capabilities at the Lakehurst side of base through their research into using a new type of metal-based powder to 3D print composite aircraft parts.
“Team INCANTATION” conducted research and testing through the six-month Naval Air Systems Command (NAVAIR) Innovation Challenge to determine if composite metal powders could be used in the AM process, more commonly known as 3D printing.
“With additive manufacturing we can explore new ways to produce and repair aviation parts in order to deliver those products more efficiently to our Sailors and Marines who need them to complete their missions,” said Kathleen P. Donnelly, NAVAIR Support Equipment (SE) and Aircraft Launch and Recovery Equipment (ALRE) Department director. “I commend the team for their innovative thinking and dedication to finding new ways to bring Speed to the Fleet.”
AM has traditionally focused on using titanium metal powders to 3D print aircraft parts, which is mechanically strong but dense and heavy compared to a lighter metal like aluminum, said Dr. Ron Poveda, NAWCAD Lakehurst Science and Technology (S&T) research engineer.
Poveda proposed a research project to look at introducing Carbon Nanotubes (CNTs), a nanomaterial, into an aluminum powder to potentially increase its mechanical strength, electrical conductivity and thermal stability.
“When you add carbon-based reinforcing materials to anything, it usually makes for a more thermally-stable structure,” said Poveda. “That’s beneficial due to the fact that the Navy uses their structures and systems in a variety of environments. If we can actually control the properties of a given printed part just by introducing these nanotubes it would be of great advantage to the Navy.”
An aluminum alloy-based composite would also be lighter and cheaper than the standard Aircraft Grade Titanium, said Patrick Thompson, NAWCAD Lakehurst mechanical engineer.
“If you could get the properties of the titanium out of aluminum, but keep it lighter and cheaper, then that’s an advantage,” said Thompson.
The team used funding from the Innovation Challenge to establish a Cooperative Research and Development Agreement (CRADA) with a New Jersey Institute of Technology professor to grow the CNTs on an aluminum alloy powder.
Mixing of CNTs with metal powders has been done in the past through the use of chemical additives and mechanical mixing, said Mike Rossini, NAWCAD Lakehurst mechanical engineer. However, the team was able to grow the CNTs organically on the surface of aluminum alloy powder without using additives through the process of Chemical Vapor Deposition (CVD).
“That in of itself is very helpful in terms of obtaining more optimized properties because the distribution of CNTs is even throughout the entire material,” said Poveda. “You don’t have any small-scale stress points within the material itself that could cause early failure."
The team then set out to create test builds from the composite aluminum metal powder using a 3D printer in the NAWCAD Lakehurst AM Facility. However, since this was the first time a metal-matrix composite with CNTs grown directly on the metallic powder surface would be 3D printed, the team had to first be sure the process adhered to government safety and environmental policy, said Igor Bezsonov NAWCAD Lakehurst systems engineer.
“One of the things that we really had to overcome to even use the machine, is we had to basically explain to safety what these Carbon Nanotubes are, how they will affect the machine due to the best of our knowledge and what health hazards they posed,” said Bezsonov.
The team had to verify printing the composite aluminum powder wouldn’t harm the 3D printer since it had only printed in pure metallic alloys, such as Titanium and Steel, up until that point.
“We worked very closely with them to make sure it wasn’t going to harm the machine and what properties we should use to make sure it was all going to work out okay,” said Rossini.
They worked with various government and academia partners to achieve the required safety, occupational health, and environmental standards and make them a part of a standard operating procedure.
What resulted not only allowed the team to conduct their research, but opened the door for JB MDL to start experimenting with 3D printing of aluminum alloys and metal-matrix composites.
Other research into using aluminum powder for AM has already started as a result of this added base capability, said Rossini.
“This work is leading towards a fundamental grasp of these kinds of materials and getting more comfortable with them and being able to use them on a widespread level,” said Thompson.
The team and AM group agree that as material properties and databases for AM parts continue to evolve, such research can expand on the fundamentals of metal composites and will inform their use-case on future parts, structures and systems.
The team’s time and efforts resulted in the successful printing of a cohesive test build using the composite aluminum metal powder, supporting their theory that 3D printing composite metals was possible.
Now that the team has proven the feasibility of printing metal matrix composites through AM, they are planning to refine the process and conduct further studies through a three-year Section 219 project.
“One of the advantages that’s easy to imagine is that by adding these Carbon Nanotubes, which are very strong and very light, to metal they can make the metal stronger without adding much more weight. One can also reduce the amount of metal needed to create parts, and with the addition of carbon nanotubes one can make the combination the same strength as the metal would be by itself,” said Bezsonov.
The team is also expanding their network, working with labs across the Department of Defense and academia to combine their knowledge in AM.
“Design requirements are becoming much more demanding these days. People, including the Navy, want lightweight with increased strength and allowing ourselves to have this mix of materials will help get us to that point,” said Poveda.