Materials

Lightweight metal composite floats on water

Lightweight metal composite fl...
The new lightweight metal matrix foam floating in a beaker of water
The new lightweight metal matrix foam floating in a beaker of water
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The new lightweight metal matrix foam floating in a beaker of water
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The new lightweight metal matrix foam floating in a beaker of water

In a development that could mean big things in the automotive andmarine industries, researchers from Deep Springs Technology (DST) and the NewYork University Polytechnic School of Engineering have created a new metalmatrix composite that is so light it can float on water.

The magnesium alloy matrix composite is what is known as asyntactic foam: a type of composite material created by filling a metal,polymer or ceramic matrix with hollow particles. In this case, a magnesiumalloy matrix is reinforced with hollow particles of silicon carbide, resultingin what the researchers claim is the world's first lightweight metal matrixsyntactic foam.

This structure helps give the material a density of 0.92 grams percubic centimeter, which is less than the 1 g/cc density of water, therebygiving it the ability to float on water and potentially be used in theconstruction of marine vessels that stay afloat even after experiencing damageto their structure. Furthermore, the researchers say it is also strong enoughto withstand rigorous marine conditions.

Additionally, the material also boasts heat resistance propertiesthat would make it a viable alternative to the lightweight polymer matrixcomposites that have been the focus of much research and development for use inboth marine vessels and automobile components as a replacement for heaviermetal-based components.

"This new development of very light metal matrixcomposites can swing the pendulum back in favor of metallic materials," saysNikhil Gupta, an NYU School of Engineering professor in the Department ofMechanical and Aerospace Engineering and the study’s co-author. "The abilityof metals to withstand higher temperatures can be a huge advantage for thesecomposites in engine and exhaust components, quite apart from structural parts."

The material starts out as a matrix made of magnesiumalloy, which is turned into a foam through the addition of silicon carbidehollow spheres developed by DST. These lightweight spheres are extremelystrong, with the shell of a single sphere able to withstand over 25,000 PSI ofpressure before rupturing. As well as adding strength, the spheres also offerimpact protection by acting like an energy absorber.

Modifying the amount of spheres that are added to thematrix allows the composite's density and other properties to be customized tosuit different applications. Just a few potential applications"floated" by the researchers include boat flooring, automobilecomponents, buoyancy modules and vehicle armor. This last example may be related to the fact that the US Army Research Laboratory collaborated on the research.

The team says the material could be in prototypes for testing within three years.

The team's study appears in the International Journalof Impact Engineering.

Source: NYU Polytechnic Schoolof Engineering

8 comments
gseattle
200 tons of iron will float on water as long as it has an air pocket, think boat.
Misti Pickles
Gseattle, it won't float for long if it has a hole in in. The key here is thst the air pockets are part of the material, meaning it won't go full Titanic when you hit the iceberg!
Douglas Bennett Rogers
These might act like the rubber spheres that are used for epoxy that goes into turbine blades to increase fracture toughness.
kmccune
Anything will float as long as it is lighter,then the water it displaces
Stephen N Russell
Replace steel for ships & subs & use this Test in yachts, then Build up Mass produce said material alone. Radical Imagine a whole cruise liner made of this
Wesley Bruce
Magnesium armour sounds like a bad idea if magnesium gets hot enough to burn it also reacts with water to produce hydrogen making for a very big fire. I once hit a burning magnesium gearbox with fire hose of water and boom! The car moved 3 cm. I moved somewhat further and faster.
P.S. It took us a whole day to find the driver. She staggered stunned from the car crash and someone picked she up thinking she was a hitchhiker and deposited her at the hotel she named without realising she had a concussion not a few too many to drink. The hotel assumed the same. She nearly died in the room.
Noel K Frothingham
gseattle, a rowboat doesn't float because an air pocket is present.
Mist EndUp, the simple presence of air pockets in 200 tons of iron is irrelevant unless there are enough to spread the density of the iron out enough to be less than the water in which it is placed. In other words, if you can't walk on water, your feet are too small. ;)
Noel K Frothingham
gseattle, a rowboat has no such air pocket yet it floats. The area upon which the load - whether 2 ounces or 200 tons - is spread is as if not more important as buoyancy.
Missi EndUp, think about that again. While the air-entrained material might be more buoyant than its solid counterpart, buoyancy CAN and will be overcome with sufficient load.