Cellular metal

Cellular metal is a stiff, lightweight metal structure consisting of many individual metal cells bonded together.
The material’s structure is like that of polystyrene, which uses many spheres bonded together to make a structure stronger than an individual sphere. the difference is that all these metal spheres are hollow.
Cellular metal has been used in vehicles to add stiffness without significantly increasing mass

Cellular metal is part of the group of ‘foamed’ metals that are gaining popularity in specialized applications and have the potential to offer benefits in a wide range of applications.

Cellular metal is created by coating styrofoam balls in a layer of metal, forming that metal round the ball, extracting the ball (generally through heating it), and then sintering many of the balls together into the desired pattern. This structure benefits hugely from the use of these many rigid spheres which are exceptionally tough given their weight. I’ve challenged at least a hundred people and no one could even slightly deform one sphere between their thumb and forefinger.

What’s important to remember though is that while the material offers a lot of stiffness and resistance to compressive forces it won’t offer the same tensile strength or impact resistance. That’s not to say it’s impact resistance isn’t also really interesting, the hundreds of small pockets are effectively an inbuilt crumple zone that consumes the energy of impacts. However, if you’re looking for something that can take a beating without changing shape, look somewhere else.

So this is not the best video, but it was this or an hour-long lecture on all metal foams, so I chose this one to share. This does cover the basics of metal foams and also show some interesting pictures of them. My apologies for the robot voice.



Material category Metals
Manufacturing properties Shaped through sintering into custom shapes
Recyclable? Yes, processed like other metals



Key limitation Limited resistance to cutting forces and damage can only be fixed through replacement.
Relationships Similar to foamed metals and polystyrene
Maker Exxentsis and others

Foamed metal is created in a similar manner to cellular metals and research about them is often linked. Metalfoam, CC BY-SA 3.0, via Wikimedia Commons

foamed metal

Polystyrene despite being extremely different in terms of its mechanical properties shares both visual and practical similarities to cellular metal. Both get their strength/lightness from being a series of small, mostly air-filled spheres that distribute weight. They are both better in compression than an extension and small amounts of damage to one part of the structure doesn’t necessarily damage the whole.

Image credit:“polystyrene” by doc(q)man is licensed under CC BY-NC 2.0

I struggled to find any good examples of cellular metals in practical use, metal foams which have a lot of similarities are tending to be the focus of research from what I can see, a paper covering this can be found Here.

The Material Sample Shop can be relied on again for a sample.