Gorilla Glass is the registered trademark for an alkali-aluminosilicate sheet toughened glass manufactured by U.S. glassmaker Corning Inc. Engineered for a combination of thinness, lightness, and damage-resistance, it is used primarily as the cover glass for portable electronic devices including mobile phones, portable media players, laptop computer displays, and some television screens. It is manufactured through immersion in a molten alkaline salt bath using ion exchange to produce compressive residual stress at the surface. This prevents cracks from propagating – for a crack to start, it will first have to overcome this compressive stress.
Corning experimented with chemically strengthened glass in 1960, as part of a "Project Muscle" initiative. Within a few years it had developed a "muscled glass" it named "Chemcor" glass. The product was used until the early 1990s in various commercial and industrial applications, including automotive, aviation and pharmaceutical uses, with particular use in approximately one hundred 1968 Dodge Dart and Plymouth Barracuda racing cars, where minimizing the vehicle's weight is essential. Experimentation was revived in 2005, investigating whether the glass could be made thin enough for use in consumer electronics, and was brought into commercial use when Apple asked Corning for a toughened glass that would eventually go into the iPhone.
The manufacturer, Corning Inc., says that Gorilla Glass' material's primary properties are its high scratch resistance (protective coating), and its hardness (with a Vickers hardness test rating of 622 to 701) — which allows thin glass without fragility. The material can also be recycled.
Gorilla Glass by 2010 had been used in approximately 20 percent of mobile handsets worldwide, about 200 million units. The second generation, called "Gorilla Glass 2", was introduced in 2012. On October 24, 2012, Corning announced that over one billion mobile devices used Gorilla Glass. Gorilla Glass 2 is 20 percent thinner than the original Gorilla Glass.
Gorilla Glass 3 was introduced at CES 2013. Gorilla Glass 3 is up to three times more scratch resistant than Gorilla Glass 2, being better able to resist the deep scratches that weaken glass. It is also more flexible. Gorilla Glass 3 is claimed to be 40% more scratch-resistant. This is Corning's first glass to be designed through an atomic-scale modeling before anything was melted in laboratories, the optimal composition being predicted using rigidity theory.
The difference in brittleness (correlated by Young’s Modulus) between Gorilla Glass 2 and 3 is 71.5 and 69.3 GPa respectively. This is a 3% difference, Just as a comparison: glass is usually around 50-90 GPa, mother of pearl is on average 70 GPa. The axial stress (Poisson’s Ratio) is almost exactly the same, 0.21 to 0.22, which can easily be down to systematic and rounding errors.The fracture toughness actually decreased from 0.68 to 0.66 MPa. in other words gorilla glass 3 is harder but more brittle.
The latest Gorilla Glass has silver ion doping that can effectively kill over 90% of the bacteria.
Corning has indicated that other areas of interest in future improvements include making it less reflective and less susceptible to fingerprint smudges, as well as changing the surface treatments and the way it is finished.
During its manufacture, Gorilla Glass is toughened by ion exchange. The material is submersed in molten potassium salt at a temperature of approximately 400 °C (750 °F), whereby smaller sodium ions leave the glass to be replaced by larger potassium ions from the salt bath. The larger ions occupy more space and are pressed together when the glass cools, causing potassium ions to diffuse far into the surface, thereby creating a 'surface' layer of high compressive stress deep into the glass, a layer more resistant to damage from everyday use.
Related Corning glass technologies
On October 26, 2011, Corning announced the commercial launch of Lotus Glass, designed for OLED and next-generation LCD displays. The intrinsic thermal consistency of Lotus Glass allows it to retain its shape and quality during high-temperature processing. Decreased compaction and variation during the crystallization and activation step further reduces stress and distortions to the substrate. This enables tighter design rules in advanced backplanes for higher resolution and faster response time. According to Corning, Gorilla Glass is specifically a cover glass for the exterior of display devices while Lotus Glass is designed as a glass substrate to be used within liquid crystal display panels. In other words, a product could use both Gorilla Glass and Lotus Glass. On February 2, 2012, Corning Incorporated and Samsung Mobile Display Co., Ltd. signed an agreement to establish a new equity venture for the manufacture of specialty glass substrates for the organic light emitting diode device market in Korea. The joint venture is based on Lotus Glass.
- List of devices with Gorilla Glass
- Schott AG's 2012 aluminosilicate cover glass Xensation, claimed to be break- and scratch-resistant, and to have 20% higher bending strength than "competitor glass types".
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