In recent years, dozens of body armor options have been created from a variety of materials, each of which has its own strengths and weaknesses. One of them is boron carbide, also known as "black diamond", so named for its incredible strength and lightness, which makes it very attractive to body armor designers.
However, according to Kelvin Se, associate professor of materials science and engineering at the University of Texas, “boron carbide is effective at stopping bullets flying at speeds less than 900 m / s, which is consistent with the combat capabilities of most pistols. At high speeds, boron carbide loses its protective characteristics. "
When more powerful ammunition is exposed to boron carbide armor, the effect of the so-called phase transition occurs, as a result of which the internal structure of the material changes - neatly located crystal structures turn into a glassy loose mass, in which atoms are scattered chaotically.
“When boron carbide undergoes a phase change, the glassy phase creates the conditions for crack propagation, ” Ce continues. "So any local damage caused by the impact of a bullet spreads freely throughout the material, causing even more damage."
Calvin Xieh and his colleagues at the University of Texas solved this problem by adding some silicon to boron carbide, which significantly increased its impact resistance.
To verify this, the team used diamond bumpers to simulate the impact of a high velocity bullet. After the experiment, the scientists evaluated the damage using an electron microscope. The result: even with a small silicon addition, the updated material withstood the impacts much more effectively - scientists recorded a 30% reduction in phase transitions and, as a result, a decrease in armor damage.