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Science Technology

New Magnesium-Alloy Foam From NYU's Nikhil Gupta Floats On Water 101

Jason Koebler writes: A new class of magnesium-alloy syntactic foam, which is made out of hollow particles to lower its weight and density is one of the strongest metals for its weight and density ever developed, which makes it ideal for use in boats. Developed by Nikhil Gupta at NYU Polytechnic University, the alloy is 44 percent stronger than similar, aluminum-based foams, and each individual sphere within the foam can withstand pressure of more than 25,000 pounds per square inch before breaking, which is roughly 100 times the pressure exerted by water coming out of a firehose. Gupta's foams are currently used by the Navy and he suspects this one will be ready for use in warships within three years.
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New Magnesium-Alloy Foam From NYU's Nikhil Gupta Floats On Water

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  • by Archangel Michael ( 180766 ) on Tuesday May 12, 2015 @11:55AM (#49674559) Journal

    Holey Floating Metal Batman!

  • Navy? Warships? (Score:5, Interesting)

    by idontgno ( 624372 ) on Tuesday May 12, 2015 @11:55AM (#49674563) Journal

    How flammable is this foamed magnesium alloy?

    A warship full of foamed magnesium would go up like a flare. It even incorporates its own oxidizer in the foam, in the air spaces. Unless they're forming the voids with inert gas.

    Unless they've paid some special attention to the flammability issue, a combat vessel made with this stuff would make the Forrestal [wikipedia.org] look like a birthday candle.

    • Well, it does say it's currently used by the Navy ... so one presumes whatever they use it for they've done testing.

      At least, you hope they have. :-P

      "Admiral, the ships hull is on fire .... Ensign bring me my brown pants"

    • ANd what are its other durability properties, like brittleness/flexibility/fracture toughness? . Ability to withstand piercing? Just because it can withstand tensile or compressive stress doesn't make it a good solution for ships.
      • Re:Navy? Warships? (Score:5, Insightful)

        by gstoddart ( 321705 ) on Tuesday May 12, 2015 @12:06PM (#49674711) Homepage

        Surprisingly, these materials aren't all that expensive, according to Gupta--the raw materials are common, and there are many factories that make syntactic foams. The difficulty is in the basic science of creating them and evaluating their properties. Gupta's lab has all sorts of machines to bend, twist, compress, pull, and otherwise stress-test a material.

        "If there's a way to break something, we can do it here," he told me.

        From the sounds of it, this aint his first rodeo, and has already thought of this stuff.

        Maybe, just maybe, the man isn't an idiot?

        • Surprisingly, these materials aren't all that expensive, according to Gupta--the raw materials are common, and there are many factories that make syntactic foams. The difficulty is in the basic science of creating them and evaluating their properties. Gupta's lab has all sorts of machines to bend, twist, compress, pull, and otherwise stress-test a material.

          "If there's a way to break something, we can do it here," he told me.

          From the sounds of it, this aint his first rodeo, and has already thought of this stuff.

          Maybe, just maybe, the man isn't an idiot?

          I didn't say it wasn't thought of. It just is not discussed and that interests me if there is going to be some discussion of a real world use.

          If there is going to be a press article about its use in ships, how about talking about more than one property? Is that unreasonable to ask?

          • Re:Navy? Warships? (Score:5, Informative)

            by ShanghaiBill ( 739463 ) on Tuesday May 12, 2015 @01:34PM (#49675701)

            Syntactic foams [wikipedia.org] have many very good properties. They use hollow ceramic beads embedded in a metal matrix. The beads are usually filled with an inert gas, most commonly nitrogen, often at far higher than 1 atm pressure. They are not particularly flammable, because the ceramic doesn't burn, and the pressurized N2 released during combustion retards the flame. It is also possible to embed halogenated frame retardants in the beads. They are strong in compression because the foam can absorb shock. They handle compression, tension, and shearing well because the beads inhibit crack propagation, sort of like how a missing link stops a zipper from unzipping. They resist heat conduction and melting better than solid metals. And, of course, they are light.

            • That is an interesting general description of this material class. The quote "They handle compression, tension, and shearing well" still leaves me questioning how well, as 'well" is a relative term. It kind of tells me they are only marginally good at it, which was my initial concern. Maybe this specific material is better in that regard?

              I would think this material on its own may not the solution for a ship deck, but possibly a layer.

              The low heat capacity and conductivity would seem to be quite nice
      • Re:Navy? Warships? (Score:5, Insightful)

        by OzPeter ( 195038 ) on Tuesday May 12, 2015 @12:06PM (#49674713)

        ANd what are its other durability properties, like brittleness/flexibility/fracture toughness? . Ability to withstand piercing? Just because it can withstand tensile or compressive stress doesn't make it a good solution for ships.

        Given that TFA says that the Navy is using this foam for the deck of the USS Zumwalt [wikipedia.org], I'm betting that they have already thought up and answered more questions that the average slashdotter could have envisaged - and that they are happy with all of the answers.

        • Given that TFA says that the Navy is using this foam for the deck of the USS Zumwalt [wikipedia.org], I'm betting that they have already thought up and answered more questions that the average slashdotter could have envisaged - and that they are happy with all of the answers.

          Great, and I don't presume they haven't. If they want to talk about it being used in ships, why just talk about one property? I guess many /.ers like yourself only care about the hyped property, but I want to know what the other properties of this material are and I assume many others do to. Why write an article and leave out so much potentially interesting information? Laziness, lack of thoroughness?

          • by OzPeter ( 195038 )

            I guess many /.ers like yourself only care about the hyped property,

            Slow down skippy, you'r projecting there.

            but I want to know what the other properties of this material are and I assume many others do to. Why write an article and leave out so much potentially interesting information? Laziness, lack of thoroughness?

            While the first FA looked like a frat boy wannabe reporter, the second FA was a link to the published paper about the material properties of this foam. And if that isn't enough of you then there is always google - or a materials science degree at a reputable school.

            • or we could discuss it here. I posed the inquiry to start that discussion. Sorry if you are not interested. You've made it clear.
              • by Anonymous Coward

                Yes, sure you did. I mean

                I guess many /.ers like yourself only care about the hyped property

                is a perfect way to start a discussion. Not.

          • by dbIII ( 701233 )

            If they want to talk about it being used in ships, why just talk about one property?

            Because it's a magazine reporter :(

      • by mlts ( 1038732 )

        I'm curious about its properties as an insulation. It might be useful as both an insulator and as a load bearing material, either alone, or perhaps as a composite.

        • You would think a 'foam' would be both good for both temperature and sound insulation. Sound insulation on a big ship would probably be a welcome quality as well.
          • by mlts ( 1038732 )

            If it has as good structural strength as TFA states, this would be very useful for automobile or RV applications:

            1: Rodents are not going to chew through it, which can make it useful for walls.

            2: If it is good at handling deformation resistance, it might be able to be used in car doors for better safety in T-bone wrecks.

            3: If it is resistant to tools, it might be useful to slow down the meth-heads who like using a long screwdriver as a master key in RV storage lots.

            This technology has a lot of promise...

            • "structural strength" can have different meanings. Concrete has great structural strength when it comes to compressive forces, but is quite brittle and breaks if not re-inforced. Its not mentioned in the article and not clear to me from the source what the other critical properties are, or if they are addressed through construction/manufacturing techniques like sandwiching.

              Meth head resistance might be a new concept they haven't though of!
          • by jbengt ( 874751 )
            Stiff foams typically aren't any good at absorbing sound.
      • by dbIII ( 701233 )
        Many metal foams so far have been very tough, and there's plenty of tests for it. One of the easiest is to cut a little bar out of the stuff, slice a notch of standard size and shape in it, then hit it with a weight on a pendulum and see how far the weight swings up after it breaks the sample. Tests are often done at low temperatures to see how that material will handle at sub-zero temperatures - not a difficult thing to do since the mid point of the metal bar is the only thing that needs to be cold at th
    • Re:Navy? Warships? (Score:5, Informative)

      by NatasRevol ( 731260 ) on Tuesday May 12, 2015 @12:06PM (#49674719) Journal

      Science fact: magnesium != magnesium alloy

      • by flopsquad ( 3518045 ) on Tuesday May 12, 2015 @12:49PM (#49675231)
        Slow clap from a Materials Engineer.
        • Well, I do have an (unused) degree in that as well.

          • Well, I do have an (unused) degree in that as well.

            Same boat! Well, unused in the sense that I'm using it for patent law and not engineering.

            Back when I was doing research, I actually spent some time working with metal oxide foams. We followed a general rule that the Navy probably follows, too: the material is a failure if it spontaneously bursts into flame in its intended operating environment.

            • by dbIII ( 701233 )
              Cool stuff. I was working with metal powder. Nitrogen gas is useful stuff to have around. Reducing in a furnace with a hydrogen atmosphere - interesting and you get to keep track of where all the exists are and make sure the corridoors are clear.
      • by khallow ( 566160 )
        But if they are calling it a magnesium alloy, then elemental magnesium is a principle component and flammability is an issue.
        • Go learn some science.

      • Science fact: magnesium != magnesium alloy

        Science fact: alloy = mixture of different elemental metals, not a chemical compound.

        So yes, magnesium alloy = magnesium. The presence of other metals in the alloy can limit the magnesium's exposure to the air and thus reduce flammability. But if you scratch it up or grind it into a powder, you're going to get pieces of raw magnesium.

        Syntactic foam is mostly hollow ceramic beads though. We used the stuff as floatation for our deep-diving robot submersible

        • by Anonymous Coward

          Science fact: alloy = mixture of different elemental metals, not a chemical compound.

          This isn't a fact at all, especially as you get away from the common aluminum and iron alloys. The chemistry involved can get quite messy, and you can get varying strength in bonding varying all the way to something resembling a salt or to something with strong covalent bonds. Chemical bonds are not in neat, completely separate categories like shown in old, low level textbooks.

          But if you scratch it up or grind it into a powder, you're going to get pieces of raw magnesium.

          Even with more boring alloys, you have a solid solution, which like a liquid solution, means breaking off a piece still results in

        • No. As an example steel normally contains iron carbides instead of free carbon in solution.
          Some are as you state but most alloys used are not just solutions of one element dissolved in another.
    • Re:Navy? Warships? (Score:5, Interesting)

      by TWX ( 665546 ) on Tuesday May 12, 2015 @12:07PM (#49674729)
      Fun fact... We bought a barbecue grille several years ago that we really liked. Used it for about year before we got a recall notice. We figured that there are three reasons to issue a recall; the product has a minor flaw that's too much of a pain for the manufacturer to correct in the field so it's cheaper to recall the product, or stupid people are hurting themselves by failing to follow directions or otherwise use the product in a safe fashion so it's just easier to recall the product (think lawn darts), or the product has a fundamental flaw that makes it unsafe and unrepairable at any reasonable expense.

      We're both pretty handy; I work on a lot of machines for fun and my wife has a Bachelor's Degree in Mechanical Engineering from MIT, so we figured if it was the first or second reason for a recall (ie, minor, correctable flaw or else improper usage) we could simply work around the issue and continue to use the grille. When we researched the recall more throughly we discovered that it was the third failure mode; the grille housing itself was made out of magnesium! Several owners had, through the course of cleaning the grille, scraped the oxidized layer off of the inside, exposing fresh magnesium, which ultimately ignited and burned the grille into the pavement. I had just thoroughly cleaned our grille when we got the recall notice but hadn't used it yet, and as we were loading it into the truck to take it back to the store I saw where the metal edge of my brush had gouged through the paint and oxide to expose fresh material.

      For all I know they've concocted a magnesium alloy for these ships that's both good at handling the corrosive effects of saltwater (along with magnesium's reactivity) and have managed to mitigate the dangers of exposure to fire or explosion, much in th way that sodium hexafluoride (the gas whose density can lower the pitch of one's voice as demonstrated on Mythbusters many seasons ago) is relatively safe compared to fluorine gas, but I'd still be nervous that some other failure mode hasn't been discovered that could be catastrophic down the road.
      • by sribe ( 304414 )

        Just curious: Perfect Flame from Lowe's?

        • by TWX ( 665546 )
          Yep.

          Ours was the model with two distinct compartments. A normal-sized one and a smaller one next to it. Part of why we liked it so much was that the small compartment was perfect for a meal for two, heated up faster and didn't use as much propane as the big compartment.

          Ended up replacing it with a Kenmore with a wide side surface. Doesn't cook quite as well as the Perfect Flame, but won't spontaneously ignite either.
      • For all I know they've concocted a magnesium alloy for these ships that's both good at handling the corrosive effects of saltwater (along with magnesium's reactivity) and have managed to mitigate the dangers of exposure to fire or explosion, much in th way that sodium hexafluoride (the gas whose density can lower the pitch of one's voice as demonstrated on Mythbusters many seasons ago) is relatively safe compared to fluorine gas, but I'd still be nervous that some other failure mode hasn't been discovered t

        • by TWX ( 665546 )
          For exposure to seawater, because seawater is used to fight fires at-sea because of its abundance? Because the salty air and high humidity at sea means that even those parts that are not in direct contact with the ocean water will still be exposed? Because storms tends to create waves that splash water all over the place, including places that are not normally wet and even places that effort is made to keep water out of?

          For the foam metals being magnesium, "New Magnesium-Alloy Foam From NYU's Nikhil Gu
          • For exposure to seawater, because seawater is used to fight fires at-sea because of its abundance?

            Which does not constitute routine exposure. Materials not routinely exposed to salt water on warships recieve no especial protection against it.

            Because the salty air and high humidity at sea means that even those parts that are not in direct contact with the ocean water will still be exposed? Because storms tends to create waves that splash water all over the place, including places that are not normal

            • by TWX ( 665546 )
              I was under the impression that Group 2 Alkaline earth metals react with water relatively readily, though not as readily as the Group 1 Alkali metals. It would seem that if water causes a reaction that reacts-away the compound, that would be a bad thing to expose to water even incidentally.
      • I think you mean sulfur hexaflouride.

        --PM

    • The secret to much of modern technology is paint. We take materials and cover them with other materials to get the best properties of each, creating micro layers.

      I am absolutely positive that they will paint the magnesium foam with non-flammable, water proof substances to keep both water and flame away from the core.

      Two or three layers of protective coatings, and the only way the foam touches water or fire is if it is penetrated by a weapon that would sink the boat no matter what it was made of.

      At the

      • Since the material is described as a foam, I assume the construction technique will be to sandwich it between metal sheets, so maybe it is not as exposed anyhow.
      • The secret to much of modern technology is paint.

        Thankfully, that's becoming less true as we move into more use of Aluminum, because paint always fails eventually and it sucks when your car's last line of defense is paint because they didn't think a corrosion coating was necessary because the paint was so awesome.

        I bought an Aluminum car specifically because paint sucks.

        • I counted corrosion coating as paint. Basically I meant any kind of thin layer put on top of the main structure.
    • Re:Navy? Warships? (Score:4, Informative)

      by Andy Dodd ( 701 ) <{atd7} {at} {cornell.edu}> on Tuesday May 12, 2015 @12:28PM (#49674983) Homepage

      Interesting question. It looks like it isn't air-in-magnesium - it's hollow air-filled SiC beads inside magnesium.

      (TFA doesn't mention the SiC part directly, but you can find more info in the linked research paper from TFA.)

    • No, the air spaces aren't necessarily filled with air or gas containing oxygen, it could possibly be filled with a relatively inert gas such as nitrogen, helium, etc. or even a gas that retards fire.

      The potential problem with this material is that a magnesium fire can rip the O2 it needs straight from the H2O bonds in water. You cannot extinguish a Mg fire with water, that would be adding fuel to the fire. A vessel made of this floating in water means that it is floating its own fuel.
    • To look at the failure modes of the material is a known thing since the sinking of the HMS Sheffield in the Falklands War. One of the reasons that ship sunk so quickly is the fire softened the aluminum superstructure, causing the various firebreaks to fail. (With the electrical system down and no way to provide substantial water, that ship was probably doomed anyway. But the concern was a similarly damaged ship even with a working water system might be doomed anyway.)
      • To look at the failure modes of the material is a known thing since the sinking of the HMS Sheffield in the Falklands War.

        The other lesson from the Sheffield, is that your computer should never be programmed to assume an incoming missile is friendly just because it was originally manufactured by one of your allies.

        • by dbIII ( 701233 )
          I think Snopes had a thing on that. If it was real perhaps it was a US made radar and IFF system, because a British one would never tag something French as friendly.
          Considering how it was flying very fast at wavetop height direct line of sight would only give a very short time to react either way.
    • by Megol ( 3135005 )

      Igniting magnesium isn't easy. IME igniting titanium is much easier. Aluminium burns well too (in fact it is often used as rocket fuel in pulverized form). And most steels can be made to burn with some effort.

      But we aren't talking about pure magnesium, we are talking about some specific alloy. Some additives are know to reduce fire hazards, one of which is calcium (itself a very reactive metal).

      And we are talking about product development - and you have to be pretty arrogant to think they don't know how to

      • I don't agree, aluminium is not easy to ignite at all in any kind of sustained way, unless you melt it and turn it into a spray, or you powder it (but then a lot of powders are pretty damn flammable), or you use high oxygen partial pressures.

        Whereas, magnesium is not that hard to ignite, and it self sustains at normal atmospheric oxygen partial pressures.

  • Magnesium is very incompatible with water, and could corrode away very quickly if it got wet. Plus it is rather flammable, with water accelerating its burning. I'm not sure that I'd want a lot of this on a warship that can be expected to be hit by enemy fire. It would go up like a flare.

  • In the US, 250 psi would be a bit much for the pressure coming out of a fire hose. 100 psi would be much more typical nozzle pressure. We test our hoses to around 300 psi, but I'd hate to be the nozzle man at 250 psi. (to get 250 psi at the nozzle, you'd have to be pulling a 2 1/2" hose) Depending on hose length, you'd be looking at somewhere around 300 GPM at 250 psi on a 2 1/2" hose.
    • to get 250 psi at the nozzle, you'd have to be pulling a 2 1/2" hose

      In my best John Wayne voice ... that's just how some of us do things, there Pilgrim.

      Oh, did you mean diameter? Never mind then.

  • Even a brick will float if you coat it with silicone. And you can boil an egg in a paper bag. News at 11.
    • Bricks have a specific gravity in the range of 1.75 - 2.4. They'll float in a pool of mercury, but not in water..
    • by ceoyoyo ( 59147 )

      Well, that's irrelevant. And also wrong: regular silicone generally has a density of 1.1 - 2 or so and brick is even more dense, so no, a brick won't float no matter how much silicone you coat it with.

  • Anybody ever been to a party where someone throws an old VW engine block on the bonfire?
  • ... I mean, the metal isn't actually lighter than water... it just has lots of bubbles in it. I mean... I could tie a helium balloon to a brick... but I'm not actually making the brick lighter am I?

    You could foam anything anything and make it lighter.

    • You could foam anything anything and make it lighter.

      But the trick is that its also very strong. Its easy to achieve one property requirement, the more you add the harder it gets.

    • by mspohr ( 589790 )

      You could foam anything anything and make it less dense

  • They should make a lump of phosphorus foam and try floating it on water.

    • by HiThere ( 15173 )

      You could probably do that in a similar way, i.e., use a phosphorous allow, form it into small beads filled with a non-reactive medium (say nitrogen) and embed it in a matrix. I doubt, however, that it would have any useful properties. I'm rather certain that, unless it was your goal in the design, it wouldn't have any spectacular ones.

      FWIW, Titanium ribbons will burn so furiously that they will not only burn in nitrogen as well as oxygen, they will actually pull oxygen away from water. (Well, ok, so wil

  • by monkeyxpress ( 4016725 ) on Tuesday May 12, 2015 @03:36PM (#49676697)

    The idea of a metal-air hybrid object that has a density less than water is already quite well developed. It is typically called a boat or ship. Some of them even have integrated air-cell buoyancy systems in the form of polystyrene blocks.

    Indeed based on his claims, it would appear this material (apparently "one of the strongest metals for its weight ever developed") would be much more important to the aviation industry.

    • A lighter metal means ship weighs less for a given size. Most of the weight of a ship is the metal. Air compartments below the waterline will help buoyancy but at the expense of ship size (and hence drag).

      Reduced boat weight means reduced displacement which means greater carrying capacity / increased efficiency / higher top speed.

      Given the size of the worldwide shipping industry and the size of the naval military this is quite an important breakthrough.

  • A fiberglass boat is stronger. Fiberglass is orders of magnitude stronger.

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