Engineering News

From nanotechweb.org: tech update:

Graphene is the strongest material in the world, according to new experiments done by researchers at Columbia University in the US. The secret to the material's extraordinary strength, says the team, lies in the robustness of the covalent carbon-carbon bond and the fact that the graphene monolayers tested were defect-free. Since "wonder material" graphene - sheets of carbon just one atom thick - was discovered in 2004, it has been shown to be an extremely good electrical conductor; a semiconductor that can be used to create transistors; and a very strong material. But now, Columbia University's James Hone, Jeffrey Kysar, Changgu Lee and Xiaoding Wei have shown that it is the strongest material ever (Science 321 385). The researchers measured the intrinsic strength of the material — that is the maximum stress that a pristine (or defect-free) material can withstand just before all the atoms in a given cross-section are pulled apart at the same time. Essentially all materials contain defects, such as microscopic cracks or scratches, which are "weaker" than surrounding material. As a result, the breaking stress of a macroscopic material depends mainly upon the number and sizes of defects it contains, rather than its intrinsic strength.

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