Glass Almost as Hard as Steel!

It seems like the days of finding a shattered screen after dropping your smartphone are coming to an end. You may have already heard of Gorilla Glass, the wonder material from Corning that as boinged on to the smartphone scene in recent years. But even that can fail and breakages have been reported. But as engineers strive to push what is possible for these small gadgets, so to do they find new ways to tweak and enhance the properties of glass.

Glass is usually made by heating minerals to very high temperatures and allowing them to cool, but much of the glass used in smartphones, and skyscrapers for that matter, is made stronger by the addition of metal atoms. For example, Gorilla glass is made stronger by the addition of Potassium (K), an alkali metal. But now, a team of Japanese research scientists have found a way to add an oxide of Aluminium, known as Alumina (Al2O3), to the glass structure. This oxide has long been coveted as a new candidate for making super strong glass, as it possesses some of the strongest chemical bonds known to man, with a dissociation energy of 131 kJ / cm3.

The scientists had hypothesised that adding Alumina to glass would make a super robust new material, but producing it wasn’t going to be easy. In their first attempts, adding the Alumina caused Silicon Dioxide (SiO2) crystals to form where the mix met the surface that it was being held in. These crystals made the made no longer see-through, and effectively worthless. It would be quite pointless to have a super strong glass that wasn’t see through, as that throws many potential applications right out the window, and the researchers knew this. They needed to develop a new production method.

Aerodynamic levitation is what they came up with, and it’s almost as sci-fi as it sounds. It involves holding the Alumina/glass mixture in the air while it forms by pushing it from below with a flow of oxygen gas. A laser is then used as a spatula to mix the material as it cools, and the result is a material that contains more Alumina than any glass to date, and it was found to be both transparent and reflective. Testing then revealed that the glass was very hard; harder than other oxidised glasses as well as most metals, and almost as hard as steel according to an article from phys.org.

The researchers remain hopeful that aerodynamic levitation could make it possible to produce all sorts of other super strong glasses, but first they need to figure out how to scale up the production process, as it currently only works in small batches. Nevertheless, it is nice to think that the despair you feel when discovering a broken screen may be a thing of the past. I don’t think anything will be able to live up to the integrity of those old Nokia bricks though. Those things could truly take a beating.

Sources not mentioned in text:

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