Graphene was discovered in 2004, giving Konstantin Novoselov and Andre Geim in 2010 a shared Nobel Prize in Physics for their work.
Researchers from the University of Massachusetts in Amherst and the Rice University in Houston, Texas built upon Novoselov and Geim's advancements and found out that graphene has the potential to be an excellent material for body armor.
Made up of a sheet of single atoms in a honeycomb structure, graphene is thin but strong, electrically conductive and flexible. Given its form, between 10 and 100 layers of the material were shown to be stronger than steel in terms of absorbing impact.
The material has never been subjected before to high-speed ballistics because graphene wouldn't be able to withstand the extreme conditions. However, Jae-Hwang Lee and his colleagues recreated conditions that would be suitable for testing graphene, turning to lasers to accelerate a microbullet much like how a bullet would be shot from a gun.
During the test profiled in the journal Science, the bullet was propelled at supersonic speeds of up to 2,000mph into layers of graphene, thanks to gases created by laser pulses in the process of evaporating a sheet of gold film. By taking note of the bullet's energy difference before and after being shot, researchers were able to determine just how much of its energy was absorbed by the graphene stack.
According to the results, graphene was able to absorb ballistic energy of up to 0.92MJ/kg, forming cracks around the impact zone similar in effect to struck tempered glass. For reference, steel is only able to absorb 0.08MJ/kg. This means graphene was 10 times better at absorbing the shock of a bullet than steel.
"The game here is energy absorption. If you can nucleate many cracks, it is a way of spreading the impact into more material," explained Edwin Thomas, Rice University's Dean of Engineering and Lee's colleague.
However, the way graphene spreads impact is also seen as a disadvantage. The researchers proposed that combining the material with others to form a composite may prevent the cracking and address graphene's problem.
Additionally, if it were to be used on armor (graphene performed twice as well as Kevlar!), it would have to be stitched in flakes. The material is brittle but how it is is overlapped with other sheets may also aid in resisting cracking.
Other studies are exploring how graphene allows proton particles to pass, a property that can potentially improve hydrogen fuel cell efficiency.
