Composite Metal Foam Stops and Pulverizes Bullets

Composite Metal Foam

A professor and her team at NC State has developed a type of metal foam that is capable of stopping some of the most powerful small arms rounds in use by the military. Sandwiched between a ceramic strike face and a Kevlar or aluminum backplate, the ballistic composite is effective even at thicknesses of 8mm 25mm or less.

Professor Afsaneh Rabiei’s Composite Metal Foam (CMF) has passed the Department of Justice certification for Level IV body armor and is being tested for other applications such as radiation protection and extreme temperature exposure.

From Popular Science:

Developed by NC State professor of mechanical and aerospace engineering Afsaneh Rabiei, this foam absorbed so much of the bullet’s impact that the indentation on the target was less than a third of an inch (8mm, to be exact). The armor itself is just an inch thick, and it’s made of boron carbide ceramics as the strike face, a composite metal foam as an energy-absorbing middle later, and either a strong aluminum 7075 or Kevlar panels backing it up.

Rabiei tested the foam against the standard NATO 7.62×51mm rounds. She also tested it against the 7.62 × 63-millimeter bullet, a type of ammunition rarely used in combat today. The composite metal foam armor met the Department of Justice’s standards for Type IV armor, useful against armor-piercing bullets.

Metal Foam From NC State:

Composite metal foams (CMFs) are tough enough to turn an armor-piercing bullet into dust on impact. Given that these foams are also lighter than metal plating, the material has obvious implications for creating new types of body and vehicle armor – and that’s just the beginning of its potential uses.

Afsaneh Rabiei, a professor of mechanical and aerospace engineering at NC State, has spent years developing CMFs and investigating their unusual properties. The video seen here shows a composite armor made out of her composite metal foams. The bullet in the video is a 7.62 x 63 millimeter M2 armor piercing projectile, which was fired according to the standard testing procedures established by the National Institute of Justice (NIJ). And the results were dramatic. (The video can also be found at

“We could stop the bullet at a total thickness of less than an inch, while the indentation on the back was less than 8 millimeters,” Rabiei says. “To put that in context, the NIJ standard allows up to 44 millimeters indentation in the back of body armor.” The results of that study were published in 2015.

But there are many applications that require a material to be more than just incredibly light and strong. For example, applications from space exploration to shipping nuclear waste require a material to be not only light and strong, but also capable of withstanding extremely high temperatures and blocking radiation.

Last year, with support from the Department of Energy’s Office of Nuclear Energy, Rabiei showed that CMFs are very effective at shielding X-rays, gamma rays and neutron radiation. And earlier this year, Rabiei published work demonstrating that these metal foams handle fire and heat twice as well as the plain metals they are made of.

Now that these CMFs are becoming well understood, there could be a wide array of technologies that make use of this light, tough material. Armor, if you’ll forgive the pun, barely scratches the surface.


LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Twitter: @gunboxready
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  • Audie Bakerson

    Until they work out a way to stop it from spraying the user’s head and neck with shrapnel, I think it will only be useful for vehicles and buildings. Maybe helmets (where even if it does hit the body it’s preferable to having hit the head) and EOD type suits

    • Demelitia

      I don’t think it’s something they would be worried about being able to solve. Lots of armour plate suffers from the problem of spalling. Aramid or glass fibre anti-spall liners are easy enough to implement. The article states the armour comes with either an aluminium or kevlar backing plate. I imagine the Kevlar would do a pretty good job of containing the much lower energy fragments to the rear; I don’t see any reason it couldn’t be included over the face of the plate.

    • noob

      apply a built up coat of urethane and you should be ok.

    • valorius

      All they have to do is spray it in gorilla liner.

    • Lemdarel

      Spall liners are already a thing for personal armour plates on the market.

    • iksnilol

      Happens with all other armors as well, we have spall liners for a reason.

      • Audie Bakerson

        So the whole “pulverizes bullets” part is just marketing hype and nothing unique?

        • iksnilol

          No, no it is definitely better than regular armor. It’s just that regular armor will also send out shrapnel in all directions.

          You gotta have a spall liner no matter what.

    • I seem to be the only one here who realizes that you’re not talking about spall– pieces of the armor itself flying off the reverse side from the shock of impact– but fragmentation of the projectile on the impact side. Still, that seems like something that could be overcome in large part by a foam or aramid cloth covering, and by incorporating a gorget or bevor to catch fragments from body or shoulder hits.

  • EC

    I think the author may have misinterpreted the article. In particular:

    “Sandwiched between a ceramic strike face and a Kevlar or aluminum backplate, the ballistic composite is effective even at thicknesses of 8mm or less.”

    That’s incorrect. The indentation after impact was 8mm or less, but the armour itself is said to be about an inch (~25mm) thick.

    I’m curious whether the 8mm indentation was on the back of the plate itself or if it was the backface signature on the clay behind the plates (which is how NIJ tests and what the 44mm limit refers to). The way the article is written is unclear.

    • Pete – TFB Writer

      Good catch. Thanks for that.

    • The Brigadier

      The article said the deflected indentation was on the back and that’s why you need either Kevlar or 7075 aluminum to back up the foam in order to catch it. The article also says the NIJ allows a maximum of 44 mm indentation for level IV armor in general. This new foam armor when struck only exhibits an 8 mm indentation. Go back and read it again if you are confused. This stuff is a very big deal and if 7075 can catch the blown back material that is only 8mm thick after being hit by a .30 caliber AP round, this stuff is a major new find in body armor.

      • EC

        The question is whether that 8mm of indentation occurred on the armour plate or on the clay behind the armour plate.

        If the indentation occurred on the clay behind the plate, that is fine. When referencing the NIJ 44mm threshold, that is measured on the clay backing, not on the armour plate itself.

        But if the 8mm indentation occurred on the plate, then that figure is not that useful. This is because the important number is how deeply the clay behind the plate was impacted, which is an approximation of energy transfer to the person who is wearing the armour plate.

        The quotes in question are:

        “this foam absorbed so much of the bullet’s impact that the indentation
        on the target was less than a third of an inch (8mm, to be exact)” -PopSci

        The word “target” is vague. If “target” means “the clay behind the armoured plate”, then great. If it means “the armoured plate”, then not so great.

        “We could stop the bullet at a total thickness of less than an inch, while the indentation on the back was less than 8 millimeters,” -NC State

        Again, the phrase “on the back” is a bit confusing. I would normally take it to mean on the other side of the armoured plate, which again is not how the NIJ runs its tests. I suppose it could be also taken to mean “behind the armour plate”, but that’s a less conventional use of “on the back”.

        Sometimes, particularly with soft armour but also to a degree with hard armour, the BFS can be larger than the deformation of the armour itself. This is why the article generates a degree of confusion, because of the language that is used.

        • The Brigadier

          I agree with you that the author could have done a better job at clarifying his article. Perhaps someone else has written about this. I will try and see today and If find anything I will post it in here.

  • Giolli Joker

    7.62×63 mm = .30-06 for those who were guessing.
    Interesting piece of news, let’s see the actual industrial development.
    Curious to see a defense related invention in the USA, coming from an Iranian scientist.

    • Rick O’Shay

      That’s more useful to me than the author used.

  • BattleshipGrey

    Can we call it adamantium?

    • Giolli Joker

      Only if we can cover skeletons and retractable claws with it…
      Maybe vibranium?

    • Major Tom

      We shall call it Gundanium.

      • LGonDISQUS
        • Obviously, it’s three times more effective if it’s painted red.

          • LGonDISQUS

            UC Forever ♡

      • Tinkerer

        I shall call it “Super Alloy Z”.
        See, my geeky reference is older, therefore better and Cooler.

        And Char Aznable wears Mazinger pjs.

      • Mazryonh

        Can it take multiple hits from 120mm shells, fired at 600 rounds a minute from a Zaku Machine Gun, without any penetrations whatsoever? If not, then there’s no chance of it being approved for Project V.

    • Edeco

      Hyperalloy combat chassis.

      • valorius

        Now all we need is a phased plasma rifle in the 40 watt range.

        • Phillip Cooper

          .. just what you see, pal…

          • TheNotoriousIUD

            “…awdough low-dah…”

        • El Duderino

          Ooozeee…nein millemetaahh.

    • valorius

      It’s Iranium.

    • The Brigadier

      Not quite. But this is a major new development in body armor. If it is not subject to temperature extreme break down like molecular polyethylene is, this new stuff will replace everything else.

  • 22winmag

    Popular Science = 9/11 pancake theory

    Everything else is just gravy

    • Gravy can’t melt steel beams, my friend. Check mate.

  • Realist

    Go Wolfpack!

  • I’m not sure I fully understand what has been achieved. A 25mm thick armor plate, made of Boron Carbide with a Kevlar backer, is already the basis for existing Level IV armor, and readily stops .30-06 AP.

    So what has the addition of metal foam between the Boron Carbide and the Kevlar achieved? Less backface defformation? Lighter? Defeats tungsten?

    Need some more deets.

    • Mark

      Way lighter.

      • nova3930

        Probably also more reliable in the face of multiple hits. Level IV is a one hit standard….

      • Do we know what the weight is? Average level IV plate is about 7lbs, with the current lightest RMA plate being 4.4lbs.

    • valorius

      It’s lighter. I didn’t realize a lvl IV plate was that thick.

    • lakdkdk

      It’s basically sloped armour, but microsized. I’m guessing they must have found a way to mass manufacture it, which is the real advance.

  • Norm Glitz

    An “indentation on the back”? Wouldn’t that be a bulge?

    • valorius

      “Forget it, he’s rolling.”

    • Sianmink

      OwO whats this?

    • Dan

      My bulge is on the front. I try not to have indentations on the back.

  • valorius

    Neat. Probably too bulky for individual personnel armor, but it could have applications for light vehicles.

    • int19h

      1″ thick is not really all that bulky for personal armor. comparatively speaking That’s pretty typical for HDPE plates. Level III HDPE is about that thick. Hybrid HDPE/ceramic Level IV is thicker.

      • valorius

        My experience with armor is Military PASGT and various civilian lvl II and IIIA soft kevlar vests.

        I didn’t realize level IV plates are that thick.

  • valorius

    If it’s suitable for space craft it’s doubtful NASA really cares how much it costs.

    • franco

      … lucky people with a big budget…

      • iksnilol

        NASA has like the lowest budget of anybody.

        • ostiariusalpha

          Well, it’s a larger budget than any other space agency, but for where it actually should be, you are correct. People (and the politicians they elect) are really short-sighted about science in general, and space exploration and development in particular.

          • .45

            There are so many things that are way more important than stopping giant rocks from ending all life on this planet, like reality TV and stuff like that…

          • Charles Applegate

            We should pitch a reality show about competing teams trying to come up with a way to stop giant rocks from ending all life on this planet!

          • We already have that, it’s called “Congress Is Too Dumb To Fund This”; it’s been live on the air since the mid-’70s, and it turns out we’re all losing.

          • Wow!

            I visited a middle school a couple months ago and the teacher went on a big rant about how space exploration is bad for the environment, a waste of money, nationalistic propaganda etc, then started talking about the kids putting their parents money into a fundraiser for aid to Africa. Private or home schooling is looking better and better by the second.

  • gunsandrockets

    “The bullet in the video is a 7.62 x 63 millimeter M2 armor piercing projectile, …”

    Uh, maybe? Sure doesn’t look like it to me. At first glance I even thought it might be 5.56mm M193 ball, a thin jacketed lead-core bullet.

  • iksnilol

    How heavy is it compared to regular armor?

  • mcjagermech

    just the thing to armor my Battlemech

    • Mazryonh

      And yet Battlemechs often use Autocannons, so when the venerable “Ma Deuce” machine guns didn’t work, they just upsized the caliber and muzzle velocities. Unless you’re using the 20-class for some reason.

      • mcjagermech

        I’m more worried about PPC fire

        • Mazryonh

          Can’t help you there. Supposedly particle beams don’t care about what kind of armour you use in real life, if they can be focussed and sustained on a target.

  • jon spencer

    Would still like to know what the actual bullets in the video is made of, caliber, weight and velocity.
    Almost looked like copper jacketed sintered lead.

  • Marketp

    Makes sense why it works, kinda like how gravel is much better than a solid wall, defensive architecture has also used marvel-like bearings in-between walls as .50 cal resistant walls.

  • Tinkerer

    I regret nothing.

  • Asgard928

    The other big question about this new product besides its effectiveness is its weight in comparison to the what is currently being used in the field. Another question many might have is can this be used to replace the armor plates currently available and at what cost. I understand it’s premature to have any definite numbers but a ballpark number would be helpful.

    One other question might be is can it be sandwiched between the two components in a chainmail or hinged mini-plate configuration to protect the sides, maybe the neck with a high collar, and the groin area without hindering the person wearing it. I suppose the weight is the most crucial question since that will affect this question.

  • adverse4

    Those Irish professors come up with the darnedest things.

  • TDog

    And if Trump had been in office earlier, this professor would not have been allowed into the country since she’s Iranian. I know the TFB tries to steer away from politics, but as this directly impacts the state of the industry – even if it’s the countermeasure to the firearm’s measure – the fact is that it just goes to show you that very few things occur in a vacuum.

  • Richard Lutz

    Seems over engineered and likely very expensive. What next? Diamonds embedded in titanium plates? Might a DU projectile fired at very high velocity burn its way through? If one doesn’t mind a bit of extra thickness why not use ultra-high-molecular-weight polyethylene plates which also serve as a floatation aid as they are lighter than water?