Overview of composite metal foams and potential applications

"Over the past 12 years, we have published a suite of papers on everything from how to make CMFs to a wide variety of the materials' properties, including how they handle high-speed impacts, radiation and intense heat," says Afsaneh Rabiei, a professor of mechanical and aerospace engineering at NC State and creator of the CMFs.

"The CMFs and their manufacturing processes are patented, but our goal for this paper is to give other researchers a thorough overview of the materials -- including previously unpublished data -- because we think the material can save lives in a variety of applications," Rabiei says. "We're hopeful that others in the research community may think of additional applications and come to us with ideas that we can collaborate on."

Previous work from Rabiei's group has shown that CMFs, in addition to being lightweight: can reduce armor-piercing bullet penetration; are very effective at shielding X-rays, gamma rays and neutron radiation; and can handle fire and heat twice as well as the plain metals they are made of. Video of the material stopping an armor-piercing bullet can be viewed at https://www.youtube.com/watch?v=lWmFu-_54fI.

The new data in the recent paper relates to previous research; for example, previously unpublished figures on how the material performs in response to high-speed impacts and cyclic loading. The information is useful to researchers, but does not change our understanding of the material's fundamental properties.

Rabiei's team is currently at work on three projects that make use of the CMFs:

* A Department of Defense-funded effort to create vehicle armor that addresses threats from small arms, blasts and fragmentation from explosives;

* A Department of Transportation-funded project to develop storage containers for transporting hazardous materials; and

* A NASA-funded project focused on structural applications for airplanes.

"If others in the research community would like to work together in exploring additional applications, we'd love to talk to them," Rabiei says.