Carbon foam is a super-handy material. It is stiff and lightweight, making it good for structural applications, and it is also great for insulating buildings. The problem is, it’s hard to make. Or rather it was hard to make, because some folks just made carbon foam by burning toast.
Chinese researchers set out to make a low-cost carbon foam, and they did it the same way you or I might bake some bread: They mixed up flour, yeast, and water, added some kneading and some waiting, then baked it. The only thing missing was salt.
Only after this does the recipe deviate from one you might want to eat. The researchers, led by Yibin Li at the Harbin Institute of Technology, dried the bread for 18 hours at 176˚F, and then put it back in the oven. Or the laboratory equivalent of an oven anyway—the dried bread went into a furnace pumped full of argon gas, so the bread could carbonize. The lack of oxygen prevented it from burning like your toast when you’re trying to get ready for work and make the kids breakfast at the same time.
The resulting carbon foam, manufactured with almost trivial ease, and clearly possible to mass-produce like regular bread, is a viable stand-in for foams made from other materials. In fact, it is more stable and less flammable than other foams.
These results demonstrate a promising method to fabricate an economical, robust carbon material for applications in industry as well as topics regarding environmental protection and improvement of energy efficiency.
As well as being a good structural material, this carbon toast could be used to insulate buildings. The toast foam also shields against electromagnetic interference, which might not be so great for letting Wi-Fi and cellphone signals move around your home, but is useful in industry. What’s more, the pore structure can be tweaked easily, varying the size of the holes in the foam just by varying the amount of yeast in the bread dough.
The combination of low-cost, tunable inner structure, and ease of manufacture could make carbon foam into a very useful material, with all kinds of applications. And to think, you could have invented it yourself, if only you hadn’t lent your argon-filled laboratory tube furnace to that cousin who never returns your stuff.
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