Based on materials from androidcentral.com
An old company and impressive innovations
Corning Incorporated is headquartered in Corning, New York, and the company was founded in 1851 – yes, it is over 160 years old. Corning Incorporated is one of the world leaders in materials science. The Fortune 500 company operates in a variety of market segments such as optical communications, display technology, specialty materials, life sciences and environmental technologies, and has expertise in specialty glass, ceramics, and optical physics.
But the real prominence of the company in the field of technology was brought by the protective Gorilla Glass, which is used in thousands of mobile devices.
I visited the research facility in Corning, NY earlier this year. I wanted to learn more about the strength of glass, its protective properties and of course Gorilla Glass and how it coexists in the market with other chemically tempered glasses such as Dragontrail from Asahi Glass Co and Xensation from Schott AG.
But why Gorilla Glass?
As a leader in 'glass', Corning saw that the consumer electronics industry needed tough, durable glass that resists pressure. Of course, the main requirements for the product were damage resistance and potential in device design. Such a product was intended to help manufacturers differentiate and improve the user experience by offering thin, bright, readable displays that provide flexibility in design.
In less than a decade, Corning Gorilla Glass has become the industry standard and high-profile brand. Many buyers look at the specifications of the devices until the moment when Gorilla Glass is indicated, this item becomes an important factor when choosing. Gorilla comes in over 1,800 models on the market and over 4.5 billion devices have been released with Gorilla Glass!
According to company representatives, over 40 manufacturers have developed Gorilla Glass models and many use it as a key feature. These are such large manufacturers as HTC, LG, Acer, HP, ASUS, Dell, Samsung, Lenovo, Microsoft and Motorola as well as Chinese giants like Meizu, ZTE, Huawei, plus Indian players like Micromax.
Recently Ford Motor Company announced that it will use this material for the windshield, rear window and bulkhead in its Ford GT supercar. What is its strength?
During my visit to Corning Labs (Corning has many other laboratories, including two research centers – the Corning Technology Center in Shizuoka in Japan and the Corning Research Center Taiwan in Hsinchu, Taiwan) in the cold February of this year, I spoke to the researchers for a while in areas of materials science working on Gorilla Glass.
Of course, the first step was to understand what is 'resistance to damage', the ability to minimize the reduction in strength upon receipt of a defect, which is determined by measuring the residual strength of a material after receiving damage.
In order to understand what damage resistance is, we conducted tests of various types
Gorilla Glass and regular soda lime glass. The latter is similar in composition to glass, which now stands in most of the windows.
The Abraded Ring-on-Ring test (ARoR) abrades the glass surface with silicon carbide particles, simulating field conditions. Then comes the usual Ring-on-Ring (RoR) test to measure the residual strength. The Scratch Ring-on-Ring test (SRoR) involves scratching the glass surface, followed by the conventional RoR test to measure residual strength.
While glass is theoretically very strong, this strength is greatly reduced when a defect occurs. Glass almost always breaks due to damage to the surface that is subjected to tensile stress (breaking or stretching).
How is Gorilla Glass made?
Corning's manufacturing process is designed to create a thin safety glass with the highest surface quality, outstanding optical clarity and dimensional stability. According to representatives of the company, the beginning of the process occurs when the raw materials are included in the glass composition, mixed in it and cooled.
The molten glass is fed into a chute called an 'isotube', which fills until the glass begins to drain equally from both edges. It then reunites at the bottom and flows into the mold, forming a continuous flat glass sheet, so thin that its thickness is measured in microns. The glass is not touched by human hands or anything else that can leave defects on the surface.
Gorilla Glass is chemically hardened through ion exchange, in which parts of the glass are cut from the 'mother' sheet and ionically exchanged.
Ion exchange is a chemical hardening process in which 'large' ions are 'pressed' into the surface of the glass, causing compression. Gorilla Glass is specially designed to maximize this process. The glass is placed in a hot bath of molten salt at a temperature of about 400 degrees Celsius. Smaller sodium ions leave the glass, and larger potassium ions from the salt bath replace them. These larger ions take up more space, and as the glass cools, they press against each other, creating a compressive stress on the glass surface. Gorilla Glass's composition allows potassium ions to penetrate deep into the surface, 'deepening' the compressive stress into the glass. This layer of compression creates a surface that is more resistant to damage.
Evolution of Corning Gorilla Glass
Corning experimented with chemically tempered glass in the 1960s as part of the Project Muscle initiative. Under the Chemcor name, 'reinforced' glass was used until the early 90s in commercial and industrial applications, most notably in 1968 Dodge Dart and Plymouth Barracuda racing cars where it was important to minimize vehicle weight.
In 2005, Corning conducted research on what type of toughened glass could be thin enough for use in consumer electronics, applied this glass technology and invented a new composition, Gorilla Glass.
Corning Gorilla Glass was commercialized in 2007 and I was told in the lab that in tests the glass outperformed the plastic coating in terms of scratch resistance, just like regular soda-lime glass in terms of resistance to damage.
This was followed by Gorilla Glass 2 in 2012, with increased strength or decreased thickness. Compared to the original Gorilla Glass, Corning Gorilla Glass 2 was 25% more resistant to damage. Buyers could choose between two improvements – the same thickness but higher residual strength, or the glass was 20% thinner with the same residual strength.
In 2013, Corning Gorilla Glass 3 appeared with its Native Damage Resistance – its own resistance to damage. Compared to Gorilla Glass 2, Gorilla Glass 3 NDR offered increased scratch resistance, less visibility of scratches, and greater residual durability after scratching.
Gorilla Glass 4
According to Square Trade Inc., “You're 10 times more likely to break your phone than lose it or get it stolen.” Broken mobile devices are a common problem, and damage resistance is firmly high on the list of things that buyers would like to see enhanced in their device screens.
Gorilla Glass 4 was formulated to avoid screen shattering, and it currently provides maximum durability, significantly reducing the chance of screen shattering from dropping your device. The company claims that Gorilla Glass 4 withstood such a load up to 2 times more efficiently than competitors. And when it comes to falling onto a hard surface, Gorilla Glass 4 survives up to 80% of the time, and soda lime glass breaks with a probability of close to 100%.
Benefits of Gorilla Glass
Of course, the main advantage of Corning Gorilla Glass is damage resistance. Gorilla Glass is chemically hardened through the ion exchange process and has a deep compression layer on the surface. This layer is a kind of armor that prevents cracks from penetrating.
The glass is also created with an exceptionally clean, smooth and flat surface and incredible optical clarity, making it an excellent coating for touch screens. It is tough enough to withstand the pressure you are accustomed to, and is exceptionally thin for a more accurate response.
Gorilla Glass is available in thicknesses ranging from 0.4mm to 2mm, and even with 0.4mm glass, the company claims that the glass performs better than many other coatings.