Introduction to Metal Foam
What’s as robust as steel, as light as aluminum, and capable of withstanding ballistic impact, fire, and radiation? The answer lies in Metal Foam, a revolutionary material that has been making waves in the scientific community.
Over a decade ago, engineer Afsaneh Rabiei of North Carolina State University invented Composite Metal Foam (CMF), a material composed of hollow metal “bubbles” embedded in steel, titanium, aluminum, or other alloys. With its exceptionally strong and lightweight properties, CMF has the potential to be applied in a wide range of industries, from air and space travel to defense. After years of rigorous testing against ballistics, blasts, vibrations, radiation, and fire, Rabiei’s company, Advanced Materials Manufacturing, is officially ready to start production.
Breakthroughs and Discoveries
Although it wasn’t the first metal foam ever invented, Rabiei claims her CMF is the strongest. A 2019 study published in the journal Composite Structures demonstrated that vehicle armor made with steel-steel CMF stopped ball and armor-piercing .50 caliber rounds as efficiently as conventional steel, but at less than half its weight.
“The CMF armor was less than half the weight of the rolled homogeneous steel armor needed to achieve the same level of protection,” Rabiei, a co-author on the study, said in a North Carolina State University statement. “In other words, we were able to achieve significant weight savings—which benefits vehicle performance and fuel efficiency—without sacrificing protection.”
Thermal Insulation and Radiation Shielding
“The presence of air pockets inside CMF makes it so effective at blocking heat, mainly because heat travels more slowly through air than through metal,” Rabiei explained in another university statement. This property of CMF could protect heat-sensitive materials, whether hazardous chemicals or vehicles carrying astronauts through space.
Space Exploration and Radiation Protection
Rabiei revealed ten years ago that CMF is capable of shielding various forms of radiation. A 2015 study published in the journal Radiation Physics and Chemistry showed that CMF is effective at blocking X-rays and gamma rays, as well as neutron radiation.
“In short, CMFs hold promise for a variety of applications: from space exploration to shipping nuclear waste, explosives, and hazardous materials, to military and security applications and even cars, buses, and trains,” Rabiei said in the statement on the ballistic tests.
A Material with Endless Possibilities
Here’s another intriguing fact: what do metal foam and ancient Romans have in common? Both have enhanced previous inventions and applications. While the Romans took inventions from other civilizations and improved them, CMF takes applications of other materials and seemingly achieves them with less weight. It remains to be seen, however, if manufacturers will also be convinced of this promising material’s potential.
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