Boron carbide is the third hardest material on Earth, after diamond and another boron-based material. In bulletproof vests and tanks, thick, heavy ceramic plates of dark gray boron carbide protect soldiers and police.
Cotton, however, couldn't be more different from boron carbide. Soft and breathable, cotton clothes are cheap and widely worn.
The trick for the scientists was combining dissolved boron with the carbon fibers inside the cotton fibers to form boron carbide.
The scientists started with a $5 package of plain, white T-shirts purchased at Wal-Mart, which they then cut into thin strips. They dipped those white cotton strips into a black solution of boron. After an hour, the strips were removed from the solution and baked in at oven at more than 1,000 degrees Celsius (1832 degrees Fahrenheit) for an hour. The heat stripped away anything that wasn't carbon or boron, and combined these two elements into boron carbide.
The resulting fabric is very different than the original materials that at the start of the process. It's lighter, stronger, tougher and stiffer than the original cotton, but it can still be bent, unlike normal boron carbide armor plates. The physical properties of the new fabric are still being tested, said Li, but "from our preliminary results we can say the test have been very, very promising."