By embedding a second material into a metal, you can produce what is called a metal matrix composite (MMC). This has various advantages, such as increasing the strength whilst at the same time reducing the density of the material. Now scientists have created an MMC so light it can float on water.
The researchers, from the New York University Polytechnic School of Engineering and in collaboration with the U.S Army Research Laboratory, created the material by reinforcing a magnesium alloy with hollow silicon carbide particle spheres. Whilst giving the new material a lower density than water, it also meant that it was strong enough to withstand the stresses of it would face if used in seafaring ships.
Although materials reinforced with hollow particles, called ‘microballoons,’ have existed for a while, this is the first time one made from metal has been light enough to float. With current research focused on producing lightweight plastic based materials to replace heavier metal parts in cars and boats, the team hope that this new MMC might be a game changer.
“This new development of very light metal matrix composites can swing the pendulum back in favor of metallic materials,” forecasted Nikhil Gupta, co-author of the study. “The ability of metals to withstand higher temperatures can be a huge advantage for these composites in engine and exhaust components, quite apart from structural parts.”
The material is produced by taking the magnesium alloy and then turning it into a foam, by adding the strong, lightweight silicon carbide particles. Whilst also found naturally, silicon carbide is mass produced and often used in products ranging from car brake discs to bulletproof vests. The research is published in the International Journal of Impact Engineering.
In fact, the researchers believe that the material that they’ve created is so strong it could potentially be used in military vehicle armour, such as that on the Ultra Heavy-lift Amphibious Connector being developed by the US military. This is due to a number of properties that the silicon carbide spheres posses. Not only can they withstand huge amounts of pressure, but because they absorb so much energy before they fracture, they also offer impact protection.
The density and strength of the material can be altered, depending on how much silicon carbide is added, and the researchers hope that it could be used in a variety of settings from car parts and boat flooring to buoyancy modules.
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