Composite metal foams could form the basis for next-generation bulletproof armour
Super-strong lightweight armour that causes bullets to shatter on impact has been made by scientists in the US working with composite metal foams (CMFs).
Afsaneh Rabiei and colleagues at North Carolina State University made sheets of light but tough armour containing a layer of CMF, made by embedding hollow steel spheres in a steel matrix. The foam is sandwiched between a sheet of boron carbide (the strike face) and a thin layer of Kevlar or aluminium (the back plate) to create armour 25mm thick. When shot with bullets that are able to pierce standard body armour, the hard boron carbide surface erodes the bullet while the foam and Kevlar absorb its energy, making just a small 8mm indentation in the back plate as it breaks apart.
The most obvious application for this and related materials is better armour for soldiers or vehicles – the advantage of using a CMF is that it is lightweight as well as strong. But the researchers say that CMFs have a number of interesting properties that would make them suitable for other applications too. They have been shown to be flame resistant and capable of shielding devices from electromagnetic radiation, for example, so they could potentially be used to make protective coatings for equipment that is sent into space.
M Garcia-Avila, M Portanova and A Rabiei, Compos. Struct., 2016, DOI: 10.1016/j.compstruct.2015.01.031