A new kind of armour plate from an Israeli defence company called Rafael Armament can protect vehicles, fuel tanks and munitions dumps from armour-piercing shells, its makers claim. The plate physically expands when hit to further deflect and disperse the energy of the shells.
When shaped-charge shells detonate they eject a focused jet of molten metal, travelling at several thousand metres per second. This can cut through extremely tough protection.
The new armour is made from a sandwich of two metal or ceramic plates, slightly separated by a filling of "micro-balloons", made from glass and each about 40 micrometres wide.
The balloons are variously filled with fuel (silicon), an oxidiser (sodium nitrate) and a catalyst (ferric oxide). When the outer plate is hit the impact smashes some of the micro-balloons, mixing the chemicals and causing a huge release of gas within microseconds.
This makes the sandwich bulge dramatically at the point of impact and defocuses the piercing jet. Because the bulge is caused by chemical gas release, not an explosion or flame, it is safe to use for protecting flammable materials.
Read the full expanding-armour patent application