Researchers from The City University of New York (CUNY) have figured out that if you stack two layers of graphene, the new material it can harden to a diamond-like consistency upon impact. Where is that quality useful? In bullet-proof armor, which tends to be quite heavy, but doesn’t have to be if this graphene-based material is employed.

Graphene, the world’s strongest material, is made up of carbon atoms that are linked together in a honeycomb pattern. It can be produced in one-atom-thick sheets. 

The new material, conceived of by CUNY associate professor Angelo Bongiorno, consists of two sheets of graphene and is called diamene. It’s comparable to foil in lightness and flexibility. But when a sudden mechanical pressure hits it, the material can temporarily become harder than a diamond. 

"Graphite and diamonds are both made entirely of carbon, but the atoms are arranged differently in each material, giving them distinct properties such as hardness, flexibility and electrical conduction," explained Bongiorno. "Our new technique allows us to manipulate graphite so that it can take on the beneficial properties of a diamond under specific conditions."

The researchers see applications of the material in wear-resistant protective coatings and ultra-light bullet-proof films. 

Elisa Riedo, professor of physics and the project's lead researcher, says this is the thinnest film that has the “stiffness and hardness of diamond” that’s ever been created.

"Previously, when we tested graphite or a single atomic layer of graphene, we would apply pressure and feel a very soft film,” she added. “But when the graphite film was exactly two-layers thick, all of a sudden we realized that the material under pressure was becoming extremely hard and as stiff, or stiffer, than bulk diamond."

What’s curious, the effect of hardening only takes place when two sheets of graphene are used. It can’t be any more or less.  

You can read the study here, in the journal Nature Nanotechnology.