Aluminum Foam
When a speeding object strikes a piece of plastic foam such as polystyrene, the work required to crush the walls of the millions of air cells in the foam slows the object down. That’s why polystyrene is ideal for use in bicycle helmets and other protective gear.

Metals such as aluminum can also form foams – and because of their greater rigidity, they could, in theory, dissipate as much energy as a polymer foam in a much thinner layer.
In practice, however, it’s been impossible to manufacture metal foams with the uniform cell sizes needed to spread out an impact evenly.
Now an Austrian company has developed a way to make aluminum foam with evenly sized cells, potentially opening the way to safer automobiles with metal-foam parts such as door side-impact beams. “Cellular aluminum has a number of advantages that no other metal has,” says Gerald Högl, CEO of Schwarzenau-based Metcomb Nanostructures. “It’s strong, light, energy absorbing, vibration and noise absorbing, nontoxic, and 100 percent recyclable.”
Metcomb’s engineers keep the cells in their foam uniform by adjusting the nanoscale oxide layer on the cell surface and by adding small-scale particles to molten aluminum, which controls its viscosity and hence the size of the bubbles that form inside it.
Engineer Jörg Wellnitz, vice dean at the University of Applied Sciences in Ingolstadt, Germany, and a member of Metcomb’s scientific advisory board, will use Metcomb’s foam to try to develop impact-absorbing car doors and armor for vehicles and buildings.
“Due to the fact that we can go from cell sizes of about two millimeters up to twelve or more, we can finely adjust the foam’s impact-absorbent properties,” says Wellnitz, who believes the material’s first commercial application will be to protect against terrorist blasts.
Keep Reading
Most Popular
The inside story of how ChatGPT was built from the people who made it
Exclusive conversations that take us behind the scenes of a cultural phenomenon.
ChatGPT is about to revolutionize the economy. We need to decide what that looks like.
New large language models will transform many jobs. Whether they will lead to widespread prosperity or not is up to us.
Sam Altman invested $180 million into a company trying to delay death
Can anti-aging breakthroughs add 10 healthy years to the human life span? The CEO of OpenAI is paying to find out.
GPT-4 is bigger and better than ChatGPT—but OpenAI won’t say why
We got a first look at the much-anticipated big new language model from OpenAI. But this time how it works is even more deeply under wraps.
Stay connected
Get the latest updates from
MIT Technology Review
Discover special offers, top stories, upcoming events, and more.