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This material is completely unsuited for making shoe soles or elbow pads; it's a two-inch-thick plate of aluminum foam with half-inch ceramic spheres embedded i

by db48x 6y ago

This material is completely unsuited for making shoe soles or elbow pads; it's a two-inch-thick plate of aluminum foam with half-inch ceramic spheres embedded in it. Around that they welded steel plates to give it a uniform surface. It'd make a very heavy but uncuttable door, but you can't make hinges or locks out of it. It would be a good material to make safes out of; those already have thick walls of composite materials designed to blunt drill bits.

throwaway9d0291 6y ago
I think that's a premature judgement. Is there any reason to think that it's impossible to scale it down? e.g. for PPE, 5mm ceramic spheres in a 1cm-thick Aluminimum foam with some 1mm steel plates on either side?
- db48x 6y ago
  Yes, there is. They hypothesize that this material works because the ceramic spheres vibrate inside the flexible matrix of the aluminum foam, damaging the grinding wheel. A thinner foam will have less ability to flex, and smaller spheres will be have less momentum to use against the wheel. Plus, if you watch the video of them grinding the material (https://static-content.springer.com/esm/art%3A10.1038%2Fs41598-020-65976-0/MediaObjects/41598_2020_65976_MOESM1_ESM.mov https://static-content.springer.com/esm/art%3A10.1038%2Fs415...), you can see that the grinding wheel penetrates over half an inch before it begins to be destroyed.
  - deleted 6y ago
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- dgoldstein0 6y ago
  For comparison I was learning about medieval armor recently. Steel breastplates are about 2mm at their thickest, typically. So that's a rather heavy duty armor idea you have. Real question then is how it would fare against bullets and piercing attacks. Cutting is only one possible threat, and usually not the biggest threat. Knife resistant bullet proof vest are already a thing, so how would this be better?
theelous3 6y ago
If you make a secure doorway with the hinges on the threat side, well, you're already toast. No need to make hinges out of anything special.

by db48x 6y ago

throwaway9d0291 6y ago

I think that's a premature judgement. Is there any reason to think that it's impossible to scale it down? e.g. for PPE, 5mm ceramic spheres in a 1cm-thick Aluminimum foam with some 1mm steel plates on either side?

db48x 6y ago
Yes, there is. They hypothesize that this material works because the ceramic spheres vibrate inside the flexible matrix of the aluminum foam, damaging the grinding wheel. A thinner foam will have less ability to flex, and smaller spheres will be have less momentum to use against the wheel. Plus, if you watch the video of them grinding the material (https://static-content.springer.com/esm/art%3A10.1038%2Fs41598-020-65976-0/MediaObjects/41598_2020_65976_MOESM1_ESM.mov https://static-content.springer.com/esm/art%3A10.1038%2Fs415...), you can see that the grinding wheel penetrates over half an inch before it begins to be destroyed.
- deleted 6y ago
  [deleted]
dgoldstein0 6y ago
For comparison I was learning about medieval armor recently. Steel breastplates are about 2mm at their thickest, typically. So that's a rather heavy duty armor idea you have. Real question then is how it would fare against bullets and piercing attacks. Cutting is only one possible threat, and usually not the biggest threat. Knife resistant bullet proof vest are already a thing, so how would this be better?

theelous3 6y ago

If you make a secure doorway with the hinges on the threat side, well, you're already toast. No need to make hinges out of anything special.