Engineers Develop Bone-Like Metal Foam That Can Be 'Healed' At Room Temperature (phys.org) 23
An anonymous reader quotes a report from Phys.Org: Now, for the first time, Penn Engineers have developed a way to repair metal at room temperature. They call their technique "healing" because of its similarity to the way bones heal, recruiting raw material and energy from an external source. The study was conducted by James Pikul, assistant professor in the Department of Mechanical Engineering and Applied Mechanics and Zakaria Hsain, a graduate student in his lab. Beyond the energy costs associated with the current process of repairing metal by melting it to a more pliable form, there are some metal components where such a repair strategy is not even an option. For example, melting removes the intricate internal structure of metallic foams, which are metals made with internal pockets of air. This arrangement of struts and gaps reduces the material's weight while maintaining its overall strength.
To heal metal foams, which generally have better structural properties than polymers, Pikul and Hsain started by finding a way for them to "sense" where they had been damaged. Rather than encapsulating additional chemicals used in repair, the researchers realized that they could use the breaking of a polymer layer as a kind of chemical signal. Pikul and Hsain used chemical vapor deposition to evenly coat each strut of the nickel foam with a layer of Parylene D, a chemically inert and stretchy polymer. Because this material's damage tolerance is slightly lower than that of nickel, it breaks first as the sample is damaged, revealing the metal underneath. The researchers could then use electroplating to build new nickel struts only on the exposed nickel where they were needed. "Pikul and Hsain healed three types of damage in their experiments on centimeter-scale samples of their polymer-coated nickel foam: samples with cracks, samples that had been pulled apart until they were connected by just a few struts, and samples that had been cleaved in two," the report adds.
"Healing the damage took about four hours, and because electroplating acts on all of the exposed nickel at once, the time it takes to heal damage is independent of the sample's size."
The study was published in the journal Advanced Functional Materials.
To heal metal foams, which generally have better structural properties than polymers, Pikul and Hsain started by finding a way for them to "sense" where they had been damaged. Rather than encapsulating additional chemicals used in repair, the researchers realized that they could use the breaking of a polymer layer as a kind of chemical signal. Pikul and Hsain used chemical vapor deposition to evenly coat each strut of the nickel foam with a layer of Parylene D, a chemically inert and stretchy polymer. Because this material's damage tolerance is slightly lower than that of nickel, it breaks first as the sample is damaged, revealing the metal underneath. The researchers could then use electroplating to build new nickel struts only on the exposed nickel where they were needed. "Pikul and Hsain healed three types of damage in their experiments on centimeter-scale samples of their polymer-coated nickel foam: samples with cracks, samples that had been pulled apart until they were connected by just a few struts, and samples that had been cleaved in two," the report adds.
"Healing the damage took about four hours, and because electroplating acts on all of the exposed nickel at once, the time it takes to heal damage is independent of the sample's size."
The study was published in the journal Advanced Functional Materials.
Freakin brilliant (Score:3, Informative)
Materials science is amazing.
Re: (Score:2)
Self-healing materials are nature's way of achieving something that is light as possible while being just as strong as it needs to be. When bone remodels itself in response to stress microfractures, it becomes stronger just where it needs strength.
I was discussing bikes the other day, and the topic came up of whether there were any more significant improvements to be had over carbon fiber frames and wheels. I think self-healing materials might be the ticket. Composite wheels and frames are lighter than t
Re: (Score:2)
Self-healing carbon fiber (with uncured resin inside that is freed by cracks) is a thing, but I don't think it works fast enough to help in real-time. I would also guess that, like a bone, it may well 'heal' into the shape it deformed into.
http://citeseerx.ist.psu.edu/v... [psu.edu]
Gundam suit on the way! (Score:2)
Re: (Score:2)
I thought this was the current precursor to Skynet's minions, but you keep thinking it's going to be for the humans...
Re: Gundam suit on the way! (Score:2)
I had thought this was going to be about... (Score:4, Interesting)
... metal foam sandwich structures, like AFS (Alumium Foam Sandwich). Integral-type foam sandwiches have pretty much the same structure as bone - you cool the skin before it can foam (or a variety of other techniques to suppress foaming in the skin), so you end up with this high density exterior around a low density core, even though it's all made out of the same substance. Could make for some amazing lightweight cast parts.
Re: (Score:2)
AFS is already in significant usage on Earth [google.com], but thanks for playing. Most is made of welded sheets, however, which makes complex shapes more difficult, so it's usually used as panels (such as flooring in high-speed trains). Casting of AFS and other metal foam structures allows for more complex shapes but isn't as mature yet.
Re: (Score:2)
you cool the skin before it can foam
. . . often said to women in the "horizontal business".
Yes, frighteningly puerile . . . but I just couldn't resist.
Re: it it ethical to make metal that can sense dam (Score:2)
Re: (Score:2)
Re: (Score:2)
Re: it it ethical to make metal that can sense da (Score:1)
At what point did AC ever come into sexual contact with you?
Apparently the memo about fucking the mind of a sjw went straight to your spam folder.
Re: (Score:3)
Re: (Score:2)
Danger, Will Robinson!
Humour Impairment detected!
Seriously, can't you recognize a joke when you read one?
Gawd, I always thought I was bad that way, but this is ridiculous....
Re: it it ethical to make metal that can sense da (Score:2)
Bone-like metal? (Score:2)
Robocop will be thrilled.
Only half bone-like (Score:2)