Video: Glassy Carbon is Ultrastrong and Elastic

The versatility of carbon-based materials is attributed to the configuration of the element’s electrons which allows for numerous self-bonding combinations. This trait gives rise to a range of materials with varying properties, such as superhard diamonds and graphite.

Now add another form to carbon’s portfolio: researchers have developed a type of ultrastrong, lightweight carbon that is also elastic and electrically conductive. A material with such a unique combination of properties could serve a wide variety of applications from aerospace engineering to military armor.A visualization of the different types of diamond-like linkages (red spheres) formed at curved surfaces or between the layers of graphene (black spheres) in this new type of compressed glassy carbon. (Image courtesy of Timothy Strobel)

The scientists pressurized and heated a structurally disordered form of carbon called glassy carbon. The glassy carbon starting material was brought to about 250,000 times normal atmospheric pressure and heated to approximately 1,800 F (982 C) to create the new strong and elastic carbon.

Previous attempts to subject glassy carbon to high pressures at both room temperature (referred to as cold compression) and extremely high temperatures proved unsuccessful. The so-called cold-synthesized material could not maintain its structure when brought back to ambient pressure, and under the extremely hot conditions, nanocrystalline diamonds were formed.

The newly created carbon is comprised of both graphite-like and diamond-like bonding motifs, which gives rise to the unique combination of properties. Under the high-pressure synthesis conditions, disordered layers within the glassy carbon buckle, merge, and connect in various ways. This process creates an overall structure that lacks a long-range spatial order, but has a short-range spatial organization on the nanometer scale.

“Light materials with high strength and robust elasticity like this are very desirable for applications where weight savings are of the utmost importance, even more than material cost,” explained Zhisheng Zhao, a professor at Yanshan University (Qinhuangdao, China). “What’s more, we believe that this synthesis method could be honed to create other extraordinary forms of carbon and entirely different classes of materials.”

Also participating in the research were scientists from Carnegie Institution of Washington (Washington, D.C. and Argonne, IL), Center for High Pressure Science and Technology Advanced Research (Shanghai, China), University of Chicago, and Pennsylvania State University (University Park, PA).