International.
In research conducted by Dirk van Baarle at Leiden University, the Netherlands, it was studied how graphene grows at the atomic scale and what determines friction with other materials.
Graphene, the ultra-thin material marveling at just a single carbon atom thick, holds the promise of such impressive applications as wear-resistant and frictionless coatings.
But early manufacturers have to be able to produce large sheets of graphene under precisely controlled conditions.
An almost frictionless and wear-resistant coating of machinery could generate huge savings in fuel and maintenance. In the world of nanotechnology, such coatings will likely have applications that we cannot currently predict. In his PhD research, Dirk van Baarle studied a candidate for such coatings: graphene. Van Baarle: "It is very difficult to produce graphene of predictable quality."
Graphene is only super strong if the wire mesh of the carbon atoms that make up the material are perfectly regular in their shape. However, with current production methods, a graphene sheet in practice is almost always composed of a mosaic of small pieces that have been grafted onto top of each other. Van Baarle was able to observe almost by carbon atom how graphene islands grow toward each other and how this process is influenced by temperature and substrate. This is the first step towards a production method to make larger, flawless graphene sheets.
A notable finding is that atomic processes occur not only in the growing layer of graphene. In practice, the surface of iridium does not perfectly match the atomic layers of the substrate. Iridium forms large steps on the surface, where graphene grows on it. But these steps can continue to grow under the graphene or they can be removed as a result of the iridium atoms in the substrate realigning. This process must also be closely controlled to allow the formation of perfect graphene sheets.
In the theoretical part of his research, Van Baarle developed a model of how friction occurs at the atomic level. When two surfaces slide on top of each other, the actual contact points are only nanometers in size, only a few atoms. Friction is at its maximum when the stiffness of the nano-protrusions is approximately medium: not too soft, but not too rigid either.
Data Source Provider: Leiden University.
