Exploring Clean Technology
Some like it strong!
As a follow up to my article “Some Like it Hot!” posted on March 15, another important dimension to advanced materials is strength. As reported by Nicola Davison of CNN on January 13, 2017, “Researchers at the Massachusetts Institute of Technology have designed a new material that is 10 times stronger than steel, a material that could change the world.” Well… it is a ‘new’ material…formed from one of the most common elements: carbon.
Graphene, an ultra-thin sheet of carbon that is thought to be the strongest material on the planet, was first discovered by Andrew Geim, a physics professor at the University of Manchester in 2002. Geim was interested in exploring how microscopically thin layers of carbon might behave by themselves. He looked to graphite...yes, the same substance used in pencils. (Pencils contain thin, weakly bonded layers of carbon - the reason why dragging a pencil across a piece of paper will produce a visible line). Geim used Scotch tape to peel away ever-thinner "flakes" of graphite until he eventually had a layer that was just one atom thick: graphene, the first two-dimensional material discovered. Under an atomic microscope, graphene looks like a flat lattice of hexagons in a honeycomb arrangement. As well as being incredibly strong, graphene is pliable like rubber and can carry a thousand times more electricity than copper. Many patents have been filed for all sorts of applications - from bendable computer screens and solar cells to long-life batteries.
Although graphene is much stronger than steel, turning it into a useful material for architecture has so far proved tricky. Graphene ‘wants’ to stay two-dimensional, so translating two-dimensional graphene into a three-dimensional ‘building block’ structure has been difficult, until MIT’s Department of Civil and Environmental Engineering started putting its thinking cap on.
Using computer modeling, MIT researchers have designed a sponge-like configuration that is just 5% the density of steel and about 10 times as strong. This makes it both extraordinarily light but able to carry heavy loads - properties that the researchers think make the material ideal for future use in design or architecture.
The MIT team needed to fuse two-dimensional flakes of graphene into three-dimensional structures, something they achieved through applying heat and pressure in cycles hundreds of times until the flakes formed a stable, integrated form.
It is reported that the researchers looked to biological materials, including butterfly wings, coral and sea urchins, for naturally occurring geometric shapes that could be a template for the new graphene material. One shape they observed at the microscopic level was the "gyroid, " a structure with a continuous surface that is also porous, a bit like a sponge. Gyroid shapes have an enormous surface area in proportion to their volume. Fused graphene flakes that are arrayed in this geometry, the researchers found, formed an unusually light yet strong material.
If you would like to peruse some of the background material, just click on http://edition.cnn.com/2017/01/13/design/gyroid-new-material-stronger-than-graphene/index.html.
This being said and knowing that advanced materials matter, I think I’ll lean back and have something both hot and strong…Coffee anyone?
Until soon… Ian