Since Genghis Khan instructed his horsemen to wear silk vests against his onslaught of arrows, body armor has come a long way—from silk to ultra-hard materials that act like impenetrable walls against most ammunition. But even these can fail, particularly if struck by high-velocity bullets. Now researchers have developed a new recipe that can improve the effectiveness of these bulletproof materials.
They found that adding just a tiny bit of silicon—a common kitchen ingredient—to boron carbide dramatically improved the material’s resilience against high-speed impacts. Upon contact with a bullet, the researchers explain in Science Advances, boron carbide undergoes a phase change similar to what happens when ice turns into water. Atoms that are systematically arranged in its crystalline state will end up haphazardly arranged as it turns into a glassy state, severely weakening the material at the point of impact.
A team led by Texas A&M assistant professor Kelvin Xie has now shown that by adding a little silicon, the boron carbide can return to its crystalline form much more quickly. The researchers also discovered that the addition of silicon can significantly improve the ability of boron carbide to absorb energy.
The findings could help researchers create a ceramic plate that’s much lighter than current boron carbide plates, which are made to be fitted into the Kevlar-like fabrics that form the protective clothing of soldiers and law enforcement officers. These textiles, with more than eight times the tensile strength of steel, distribute the force of an impact over a larger area. They are also a key component of the lightweight armor used by armed helicopters and aircraft.