A team of researchers at the Massachusetts Institute of Technology (MIT) claims to have designed one of the strongest lightweight materials known to man by compressing and fusing flakes of graphene into a sponge-like shape. The object has been made into a 3D-printed form that’s five per cent the density of steel but ten times stronger.
In its two-dimensional form, graphene is thought to be the strongest of all known materials. With a tensile strength of 130 GPa (gigapascals), it is more than 100 times stronger than steel. The first isolated sample of graphene was discovered in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester. They were awarded the Nobel Prize in Physics for their discovery in 2010.
But until now, researchers have been unable to translate the two-dimensional strength of graphene into useful three-dimensional materials. Successfully translating the graphene into a three-dimensional shape is a small step towards using the material in vehicles, buildings and other devices.
So how did they do it?
The findings were published in the journal Science Advances, in a paper by Markus Buehler, the head of MIT's Department of Civil and Environmental Engineering (CEE) and the McAfee Professor of Engineering; Zhao Qin, along with a CEE research scientist and two graduates.
To make the sponge-like shape, the researchers analysed graphene down to the level of individual atoms to better understand its properties. The team was able to compress small flakes of graphene using a combination of heat and pressure. This process produced a strong, stable structure similar to some corals. These shapes, which have an enormous surface area in proportion to their volume, proved to be remarkably strong.
They created a variety of 3D models to test the objects’ strength, subjecting them to various tests. In computational simulations, which mimic the loading conditions in the tensile and compression tests performed in a tensile loading machine, one of the objects was found to be ten times as strong as steel.
The researchers say there are many possible applications for the material. “You can replace the material itself with anything,” Markus Buehler told MIT News. “The geometry is the dominant factor. It’s something that has the potential to transfer to many things.”
Various examples are given. Concrete for a structure such as a bridge might be made with the material, providing comparable strength with a fraction of the weight. The material might also find application in some filtration or water processing systems because of its tiny pore spaces.
The findings also put to bed any suggestion that it will be possible to make 3D graphene structures that are lighter than air, which had been previously suggested by other research teams. Buehler’s study shows that the material wouldn’t have sufficient strength at such a low density.
The research was supported by the Office of Naval Research, the Department of Defense Multidisciplinary University Research Initiative, and BASF-North American Center for Research on Advanced Materials.
In one of our most interesting blogs from 2016, we looked at four ways graphene could play an important role in many products and processes in the future. From boosting our internet speeds to cleaning contaminated water, you can read the full post here.
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