3D-Printed Syntactic Foams Might Bring Submarines to New Depths

A team of materials engineers at the NYU Tandon School of Engineering developed syntactic foam filaments that could be 3D printed using off-the-shelf commercial printers. (Image courtesy of NYU Tandon.)

New developments in commercial 3D printing could allow submarine manufacturers to create complex, durable, and lightweight parts that can withstand increased oceanic pressure.

A new 3D printing method for creating syntactic foams could take submarines to whole new ocean depths. This new method might soon offer underwater vehicle manufacturers the ability to create high-quality parts in complex shapes using commercial 3D printers.

Syntactic foams are a lightweight and durable material commonly used to manufacture airplanes, ships, land vehicles and submarines. These foams are comprised of billions of microspheres—microscopic ceramic spheres or hollow glass—mixed in epoxy or plastic resin.Due to the high strength and buoyancy of syntactic foam parts, they are commonly used in the manufacturing of submarines, including the Deepsea Challenger and the next-generation Alvin deep-sea explorer.

This new 3D printing process uses syntactic foam filaments made with high-density polyethylene (HDPE) plastic resin and microspheres from recycled fly ash—an industrial waste by-product created from coal combustion. These microscopic spheres are small enough—between 0.04 and 0.07mm in diameter—to flow through a commercial 3D printer nozzle without clogging it. But since these hollow microspheres are relatively fragile, they must be mixed into the HDPE resin and printed without being crushed to avoid adding density to the foam and reducing its buoyancy.

Electron micrograph of syntactic foam with fly ash microspheres. (Image courtesy of Nikhil Gupta/NYU Tandon.)

The traditional method for creating syntactic foam parts uses injection molding. Once they are molded, individual parts are secured together with adhesives and fasteners to create complex-shaped parts for vehicles. However, this method produces vulnerabilities when the foam parts are under pressure. However, with 3D printing, manufacturers could potentially make complex parts of various shapes in a single form that are as strong as those created with current methods but without the same vulnerabilities.

This breakthrough is especially promising for submarine manufacturers. With the use of commercial 3D printers, manufacturers could print components that are both light enough and strong enough to withstand ocean depth and pressure.

Ashish Kumar Singh (left), a doctoral student of Nikhil Gupta (right), associate professor of mechanical and aerospace engineering at NYU, reported the development of 3D printing syntactic foam filaments using off-the-shelf commercial printers. (Image courtesy of NYU Tandon.)

In collaboration with materials scientists from India, Nikhil Gupta—an associate professor of mechanical and aerospace engineering—and his students at New York University Tandon School of Engineering developed this first process of creating syntactic foams using 3D printers. Their goal was to develop a filament for use in commercial 3D printers without the need to change any printer hardware.

Now that they have developed 3D-printed materials with the same tensile strength and density as those created with traditional injection molding methods, the team’s next step is to optimize these materials for a variety of uses, including underwater vehicles that can function at certain ocean depths.

For an in-depth look at this research, read Part 1 and Part 2 of the team’s findings, which are published in JOM, the Journal of the Minerals, Metals & Materials Society.

Interested in cool submarine tech? Check out NASA's extraterrestrial submarine design!