Making Glass Stronger than Steel

It’s almost everywhere you look. When you glance at your phone, peer upwards at high-rise buildings or check your right and left before making a turn in your automobile. Glass is fairly ubiquitous. And the journey to strengthen the material just made some strides.

Univ. of Tokyo and Japan Synchrotron Radiation Research Institute researchers have developed a glass material with high elasticity and hardness, making it stronger than many metals.

“Glasses with high elastic moduli and high hardness values have been in demand for years because the thickness of sheet glass with these properties can be decreased while maintaining its strength,” write the researchers in Scientific Reports. “Thinner and lighter glass are desired for windows in buildings and cars, substrates for (thin-film transistor) displays and covers of smart-phones.”

Most glasses are based on the compound silica, a principal component of sand. However, the newly developed glass is infused with significant amounts of alumina, which is an oxide that has one of the highest dissociation energies. Traditionally, the glass forming ability of a composition decreases as alumina quantities increase, the researchers report. Such compositions also prove difficult to work with due to high melting temperatures.

According to Popular Science, when the team first attempted to produce glass with alumina in it, opaque silicon dioxide crystals formed on the glass inside the container, causing it to lose its transparent quality.   

To avoid this problem, the researchers developed a container-less fabrication technique called aerodynamic levitation. “The new process involves causing the mix to be held in the air while it is forming, by pushing it from below with oxygen gas and then using a laser as a spatula to mix the materials together,” Phys.org reports.

The resulting glass is both transparent and reflective, and is composed of 50% alumina. Further, it was twice as strong as typical glass, and almost on par with steel.

“We will establish a way to mass-produce the new material shortly,” said study co-author Atsunobu Masuno to The Asahi Shimbun. “We are looking to commercialize the technique within five years.”

But those who shatter their smart phones on a regular basis may want to belay celebration. Carmen Drahl, a chemist contributor for Forbes, pointed out some sobering facts. First, the spherical glass pieces produced were about the size of candy sprinkles. Second, the glass wasn’t exactly unbreakable. Some samples developed radial cracks under certain forces, a fact the researchers acknowledged in their paper.

“What this report describes isn’t some miracle material, but a well-above-average performing glass that seems promising on a tiny scale,” writes Drahl.     

Still, the development is a step in the right direction. And iPhone users with shattered screens can look forward to a day when dropping their phone won’t inadvertently make Candy Crush more difficult to play.