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

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.

Comments

Robin

[Archangel Michael]

Holey Floating Metal Batman!

Navy? Warships?

[idontgno]

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 look like a birthday candle.

Re:Navy? Warships?

[gstoddart]

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"

Re:Navy? Warships?

[gstoddart]

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?

Re:Navy? Warships?

[OzPeter]

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, 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.

Re:Navy? Warships?

[NatasRevol]

Science fact: magnesium != magnesium alloy

Re:Navy? Warships?

[TWX]

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.

Re:Navy? Warships?

[Mr D from 63]

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?

[Andy Dodd]

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.)

Re:Navy? Warships?

[flopsquad]

Slow clap from a Materials Engineer.

Re:Navy? Warships?

[Mr D from 63]

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.

Re:Navy? Warships?

[ShanghaiBill]

Syntactic foams 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.

Re:Uhhh

[Em Adespoton]

"magnesium alloy"

As a comparison, Inox, or "stainless steel" is a steel alloy. Steel is very incompatible with water, and could corrode away very quickly if it got wet. And yet, add that chromium to create a new alloy, and suddenly you've got a slightly softer metal that doesn't oxidize.

See also: transparent aluminium, silicon vs silicone, etc.

Re:250 psi?

[gstoddart]

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.

Boats are already floating metal

[monkeyxpress]

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.