A metal composite so light that it can float on water has been devised by a team of US researchers in a bid to make unsinkable boats.
Although foams have been around for many years, researchers said this was the first development of lightweight metal matrix syntactic foam.
The magnesium alloy matrix composite is supported with silicon carbide hollow particles and has a density of 0.9g/cc compared to 1g/cc of water, which allows it to be strong enough to withstand sea conditions.
Nikhil Gupta, co-author of the research study, said: “This new development of very light metal matrix composites can swing the pendulum back in favour of metallic materials.
“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.”
A single carbide sphere's shell can withstand pressure of over 25,000 pounds per square inch before breaks – the equivalent of one hundred times the maximum pressure in a fire hose.
The hollow particles also offer impact protection to the syntactic foam because each shell acts like an energy absorber during its fracture.
The composite can be customized for density and other properties by adding more or fewer shells in to the metal matrix to fit the requirements of the application and can also be used with other magnesium alloys that are non-flammable.
The new composite has potential applications in boat flooring, automobile parts as well as vehicle armour.
The study was published in the International Journal of Impact Engineering.