Graphene has remarkable properties that could revolutionize electronics, and now new research shows that the material is better than Kevlar at stopping bullets fired at supersonic speeds. Early investigation reveals the modern material is able to absorb 10 times as much energy as steel before failing.
Graphene consists of single layers of carbon atoms, arranged in a sheet. Flexible video screens resembling paper could soon be constructed from graphene, sheets could be bonded onto human skin, and spinal cords could be repaired using the revolutionary material.
Rice University researchers examined the behavior of graphene when subjected to simulated impacts from high-velocity bullets. A laser guidance system directed a silica bullet toward a small graphene target, containing several layers of the material. The laser evaporated a gold film, producing puffs of gas that accelerated the bullet toward its minuscule target at speeds up to 2,000 mph. Velocities of the projectile, taken before and after impact, were used to calculate the amount of energy absorbed by the target.
"We cannot use conventional techniques such as a gun barrel or gunpowder [on this scale]. Instead we used a laser to accelerate a microscale silica bullet [at the multilayer graphene target]," said Jae-Hwang Lee of the University of Massachusetts.
Study of the targets determined how energy from the impacts was distributed throughout the material. The tiny graphene targets distributed the kinetic energy of the impacting projectile first into a cone and then into cracks that radiated from the point of impact, like tempered safety glass.
"The game here is energy absorption. If you can nucleate many cracks, it is a way of spreading the impact into more material," Edwin Thomas, dean of engineering at Rice University, told the press.
One popular analogy is that graphene is strong enough to withstand the weight of an elephant balancing on a pencil. However, this is the first major study to examine how the substance could be utilized in blocking bullets.
For now, high-quality graphene can only be produced in small quantities, preventing commercial production of bulletproof jackets from the substance. Graphene was first discovered in 2004 and is noted for its static strength and stiffness that comes from its two-dimensional honeycomb structure.
Kevlar remains the most common material used to manufacture garments designed to ward off bullets. Created from aromatic polyamide, it was first developed in 1965 by Stephanie Kwolek, a Dupont researcher. By the early 1970s, it was being used as a replacement for rubber in wheels of race cars. Today, the material is utilized in bicycle tires, sails for boats, and even drum heads.
Analysis of projectile impacts in graphene was profiled in the journal Science.