No, Japanese scientists haven’t invented unbreakable glass

By Joel Hruska 

Yesterday, the Internet was aflutter with news that scientists in Japan had invented a type of “unbreakable” glass as strong as steel. This is not true — but the Japanese researchers still might have their hands on an incredibly useful substance. For years, scientists have known that adding alumina (a white powder) to glass can create a material that’s extremely hard. The resulting product, Aion (sometimes called transparent aluminum and marketed as Alon) is capable of serving as bulletproof glass at a fraction the weight of traditional materials. It’s 85% as hard as sapphire and optically transparent.

Optical transparency of the new panel

The problem with traditional Al₂O₃ glass is that it becomes increasingly difficult to manufacture as the percentage of aluminum increases. The high melting point of aluminum has limited its use in glass manufacturing. The research team in Japan used a technique called containerless manufacturing to combine alumina with tantalum, which is typically used in making computer electronics. The two materials were combined at high pressure and heat, then levitated with oxygen gas and melted via laser.

The result? Tiny glass spheres of 54Al₂O₃-46Ta₂O₅. Multiple evaluations demonstrated that the spheres were elastic (meaning they could deform and return to their original shape), hard (they resist scratching), and thermal shock resistant. The researchers claim that their measured values for this new type of glass put them on par with other oxide glass, though the listed properties for transparent aluminum appear to give it a definite lead in multiple categories.

Is this a major breakthrough? There’s no way to know just yet. Glass is ubiquitous in the modern world, but the glass covering your smartphone has different properties compared with a drinking glass or a mason jar. It’s not enough to simply make glass hard, or strong, or tough — it needs to embody an entire range of characteristics, while retaining the transparency and low reflectivity that make it prized for various applications. This came up when we thought Apple might adopt sapphire screens for the iPhone — while sapphire is extremely hard (essentially scratch-proof unless you’ve got an unusual abundance of diamond in your home), it isn’t necessarily less prone to breaking than high-end glass.

Hardness, stiffness, strength, toughness — these words identify specific traits of a material. In this case, the researchers created a glass that’s both highly elastic and strong, with good thermal shock properties. Saying that it’s unbreakable or stronger than steel, however, isn’t accurate. What the data does show is the creation of a new type of glass that’s transparent, with good mechanical properties, and highly refractive. It’s a strong overall showing and could lead to improved devices in the future.

Even if the researchers can create use this technique to create a new, superior type of smartphone glass, it’s not clear if those benefits would actually benefit consumers in the form of better displays. In the past, every improvement to smartphone glass has been immediately used to make the same device thinner, not stronger. Corning’s Gorilla Glass 2 was 20% thinner than Gorilla Glass. Gorilla Glass 3 was even thinner (down to 0.4mm compared to 0.55mm for Gorilla Glass). The implication of this is that a screen made to original GG specifications would be even stronger than the original — but few companies have dared to take this route. Shaving a tenth of a millimeter off a design is still seen as more important than emphasizing durability. Since both Apple and Samsung make money on hardware sales, phone companies will never have a huge interest in manufacturing products to maximize stress tolerance.