Lightweight 3D graphene forms 10 times stronger than steel
Graphene is thought to be the strongest of all known materials. However, graphene is a two dimensional form of carbon, and researchers have had a hard time translating graphene’s strength into useful, three dimensional materials. Until now. Researchers at MIT have developed 3D forms of graphene that can be ten times as strong as steel, but are much lighter.
The team was able to compress small flakes of graphene by using a combination of heat and pressure. This process produced a strong, stable structure of which the form resembles that of some corals. These shapes, which have an enormous surface area in proportion to their volume, proved to be remarkably strong.
The 3D graphene material is composed of curved surfaces under deformation. It resembles what would happen with sheets of paper. Paper has little strength along its length and width, and can be easily crumpled up. But when made into certain shapes, for example rolled into a tube, suddenly the strength along the length of the tube is much greater and can support substantial weight. Similarly, the geometric arrangement of the graphene flakes after treatment naturally forms a very strong configuration.
The team used 3D printed models of the structure, enlarged to thousands of times their natural size, for testing purposes.
For actual synthesis, the researchers say, one possibility is to use the polymer or metal particles as templates, coat them with graphene by chemical vapour deposit before heat and pressure treatments, and then chemically or physically remove the polymer or metal phases to leave 3D graphene in the gyroid form.
The new findings show that the crucial aspect of the new 3D forms has more to do with their unusual geometrical configuration than with the material itself. This suggests that similar strong, lightweight metamaterials could be made from a variety of materials by creating similar geometric features (read more about metamaterials here).