Forget Kevlar: New Graphene Material May Create Bullet-Proof Materials in the Future

Forget about Kevlar; graphene may be the new bullet-proof material. Scientists have taken a new look at graphene's strength by shooting it with microbullets.

When graphene was discovered a decade ago, scientists believed that the two-dimensional carbon honeycomb was much stronger than steel. Yet this new study reveals that the material is, on average, a staggering 10 times better at steel when it comes to dissipating kinetic energy.

In order to test exactly how strong graphene is, the researchers conducted a laser-induced projectile impact test (LIPIT). This test used energy from a laser to drive microbullets away from the opposite side of an absorbing gold surface at great speed. The researchers further enhanced this test by modifying it to fire single microscopic spheres with great precision at speeds approaching 3 kilometers per hour, which is much faster than a bullet from an AK-47.

The researchers created a custom stage to line up multilayer graphene sheets mechanically drawn from bulk graphite. Then, they tested sheets ranging from 10 to 100 nanometers thick, which is up to 300 graphene layers. They used a high-speed camera to capture images of the projectiles before and after hits to judge their speed and to view damage to the sheets.

In every case, the spheres punctured the graphene. But instead of a neat hole, the spheres left a fractured pattern of "petals" around the point of impact. This indicated that the graphene stretched before breaking.

In fact, the scientists found that the graphene is a stretchy membrane that can distribute the stress of the bullet over a wide area defined by a shallow cone centered at the point of impact. In theory, controlled layering of graphene sheets could lead to lightweight, energy-absorbing materials.

"Ideally you would have a lot of independent layers that aren't too far apart or so close that they're touching, because the loading goes from tensile to compressive," said Edwin Thomas, one of the researchers, in a news release.

The findings reveal that graphene is an extremely strong and flexible material that could be used for a wide range of applications in the future.

The findings are published in the journal Science.

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