Researchers at NYU have developed a metal matrix foam light enough to float on water.

According to the team from Deep Springs Technology (DST) and the New York University Polytechnic School of Engineering, although syntactic foams have been around for many years, this is the first development of a lightweight metal matrix syntactic foam.

The material is made of a magnesium alloy matrix which is then turned into foam by adding strong, lightweight silicon carbide hollow spheres developed and manufactured by DST. It has a density of only 0.92 g/cm3 compared to 1.0 g/cc of water.

Significant efforts in recent years have focused on developing lightweight polymer matrix composites to replace heavier metal-based components in automobiles and marine vessels. Amphibious vehicles such as the Ultra Heavy-lift Amphibious Connector (UHAC) being developed by the U.S. Marine Corps could especially benefit from the light weight and high buoyancy offered by the new syntactic foams, the researchers explained. Not only does it have a density lower than that of water, it is strong enough to withstand the rigorous conditions faced in the marine environment. A single silicon carbide hollow sphere’s shell can withstand pressure of over 25,000 pounds per square inch (PSI) before it ruptures, the team said.

Researchers have developed a metal matrix foam that is light enough to float on water.
Researchers have developed a metal matrix foam that is light enough to float on water.

Favoring metal

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 into the metal matrix to fit the requirements of the application. This concept can also be used with other magnesium alloys that are non-flammable.

The new material could also be suitable for automotive applications, as it combines light weight with heat resistance.

‘This new development of very light metal matrix composites can swing the pendulum back in favor of metallic materials,’ suggested Dr Nikhil Gupta, an NYU School of Engineering professor in the Department of Mechanical and Aerospace Engineering and the project’s co-author.  ‘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 authors published their findings in the International Journal of Impact Engineering

This story is reprinted from material from NYU, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.