Engineers in the U.S. have shown that graphene — a remarkable material that's only 10 to 100 nanometers thick — could make for excellent body armor, absorbing 10 times the amount of energy than steel before failing.
Since its discovery in 2006, graphene has been hailed as the next big thing in materials technology. At a mere one atom thick, it is incredibly flexible, eternally stretchy, conductive, and self-cooling. Eventually, graphene could be used to produce video screens as thin and flexible as paper, super-thin cybernetic devices that can be grafted onto living tissue, and electrically conductive transmitters that can repair damaged spinal columns.
But it now appears that graphene can also be used to create super-strong body armor. A team from Rice University recently became the first to subject the material to the extreme conditions of high speed ballistics. But because the size of the graphene patches is still so small, a laser was used to accelerate a microscale silica bullet at a multilayer graphene target.
Chemistry World explains more:
The bullet was propelled into stacked graphene sheets at supersonic speeds of up to 2000mph by the gases produced by laser pulses rapidly evaporating a gold film. The team calculated the energy difference of the bullet before and after to determine the energy absorbed.
Neil Bourne, director of the National Centre for Matter under Extreme Conditions in the UK, who was not involved in the research, described the technique as 'very exciting'. 'They have taken a standard laboratory ballistics configuration and demonstrated its utility on microscopic scales,' he says.
Graphene was able to absorb up to 0.92MJ/kg of ballistic energy in the test, with cracks forming around the impact zone. By comparison, steel targets only absorbed up to 0.08MJ/kg at the same speed.
'The game here is energy absorption,' says Edwin Thomas, Lee's colleague and Dean of Engineering at Rice University, US. 'If you can nucleate many cracks, it is a way of spreading the impact into more material.' Thomas likened the effect seen in graphene to that of tempered safety glass, a material engineered to spread damage and not locate it to a point.
Graphene's dynamic strength, argue the researchers, is significant as it may behave similarly in materials specifically engineered to stop bullets, including kevlar — a fabric composed of aromatic polyamide threads.
Read the entire article at Chemistry World. And check out the entire study at Science: "Dynamic mechanical behavior of multilayer graphene via supersonic projectile penetration."