Bulletproof graphene creates super-strong body armor


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Protect your entire body from a single atom

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A layer just one carbon atom thick can absorb a bullet-penetrating impact, and recent tests suggest that pure graphene could perform twice as well as fabrics currently used in bulletproof vests, making it ideal body armor for soldiers and police.

Graphene is a single sheet of carbon atoms bonded together in a honeycomb pattern. It’s already used in computers and electronics because it’s a good conductor of heat and electricity. It’s also lightweight yet incredibly strong, which could make it the perfect material for bulletproof vests.

But testing such a thin material by firing a high-velocity bullet at it is difficult, because the atomic-thick material would completely fracture upon such an impact. Previous studies have used nano-pokers to push graphene at walking speed (less than one meter per second) or a shotgun approach using multiple laser pulses. But these methods couldn’t prove graphene’s actual strength against a high-velocity bullet, says Jae-Hwang Lee of the University of Massachusetts Amherst.

To test graphene’s capabilities, Li and his colleagues devised a new miniature ballistics test: They used laser pulses to superheat a gold filament until it vaporized, acting like gunpowder, firing micrometre-sized glass bullets at 10 to 100 pieces of graphene at three kilometres per second – roughly three times faster than a bullet fired from an M16 rifle.

The team found that the graphene sheet dissipates the kinetic energy of the bullet by stretching in a cone shape at the impact point and then cracking radially outwards. Li said that while this cracking is one of the weaknesses of single-layer graphene, it still performs twice as well as Kevlar and can withstand 10 times the kinetic energy of steel. Using multiple layers of graphene or incorporating it into a composite structure can also prevent the cracks from propagating, Li said.

Researchers have previously studied graphene as armor, but Li’s paper is the first to explain how the material absorbs kinetic energy. Because sound waves travel three times faster through graphene than through steel, the material can quickly absorb and dissipate energy far beyond the point of impact, effectively slowing the bullet and preventing it from penetrating. What’s more, Li’s microbullet method could also be used to study other high-performance materials in extreme conditions.

Journal Reference ScienceDOI: 10.1126/science.1258544

Amended on January 1, 1970

When this article was originally published, the comparison of experimental bullet velocities to those of an M16 rifle was incorrect.

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