Modern smartphones are fragile. There's no doubt about that. Just look at the thriving smartphone case market. We kind of did this to ourselves, making those sophisticated electronic devices out of glass, but while the back of our smartphones could be made out of anything, the screen needs transparent material over it in order to… well, function.
Enter Gorilla Glass! Most of you probably know the story. When Steve Jobs introduced the original iPhone back in 2007, it featured a plastic screen that quickly got scratched after a day of use. Mr. Jobs contacted Corning, an American company specializing in glass and ceramics, and asked them to fix the issue.
The first iPhone was quickly upgraded and shipped with "optical-quality glass to achieve a superior level of scratch resistance and optical clarity." This glass was made by Corning and, one year later, introduced as Gorilla Glass.
What people probably don't know is that Corning's first experiments with such glass began way back in the 1960s. In 2005, the company began steps toward developing a light enough product to be used with consumer electronics.
What is Gorilla Glass?
We're all familiar with tempered glass. This type of glass is treated at high temperatures (600 °C) to make it harder and more scratch-resistant. Gorilla Glass is a bit different. It uses chemical processes to change the composition of the glass to make it harder and more resistant to damage.
But while tempering uses only high temperatures and rapid cooling, Gorilla Glass requires a more complex process called ion exchange.
How is Gorilla Glass made?
Gorilla Glass is made by chemically strengthening normal glass through a process called ion exchange. What happens is that smaller sodium ions are taken out of the glass and replaced with bigger potassium ions. These bigger ions are stuffed together, and the forces between them are also greater, making the surface of the glass more durable.
Here's the whole process in detail:
A sheet of regular glass is dipped in a bath of hot, molten potassium salt at temperatures around 400 °C.
The extreme heat makes sodium ions move out of the glass, while potassium ions move in their place.
Because potassium ions are larger, they get squeezed together, forming tighter bonds.
The glass is taken out of the salt bath and left to cool.
When the glass cools, a stress layer is formed consisting of these closely packed potassium ions, now permanently frozen in the crystal lattice of the glass.
The layer of potassium ions gives Gorilla Glass its scratch-resistant characteristics and its durability.
Gorilla Glass generations
Since the invention of Gorilla Glass in 2008, Corning has been developing and perfecting the technology, resulting in different Gorilla Glass models. The first generations used simple numbers and sometimes abbreviations such as SR+ and DX+, but from 2020 onward, Corning decided that names were better for the business and introduced the Gorilla Glass Victus.
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You will find a comprehensive table of all Gorilla Glass models and their characteristics below:
Generation
1
2
3
4
5
SR+
6
DX/DX+
3+
Victus
Victus 2
Armor
Announced
2008
2012
2013
2014
2016
2016
2018
2018
2019
2020
2022
2024
Density in g/cm3
2.42
2.39
2.42
2.43
2.4
2.4
2.41
Young's Modulus in GPa
71.5
70
65.8
77
77
77
79
Poission's Ratio
0.21
0.22
0.22
0.21
0.21
0.21
0.22
Shear Modulus in GPa
29.6
28.5
26
31.7
31.9
31.4
32.2
Vickers Hardness (200g load): Unstrengthened in kgf/mm2
534
555
489
559
611
590
595
Vickers Hardness (200g load): Strengthened in kgf/mm2
649
653
596
608
678
651
670
Fracture Toughness in MPa m0.5
0.68
0.66
0.67
0.69
0.7
0.76
0.82
Coefficient of Thermal Expansion (0–300 °C) in 10-7/K
81.4
75.8
86.9
78.8
75.2
72.5
58.8
Gorilla Glass Armor
In January 2024, Corning unveiled Gorilla Glass Armor, the latest generation of chemically fortified glass, and its debut coincided with the launch of the Galaxy S24 series. Corning says that this glass excels in drop tests on concrete, exhibiting up to three times better performance and boasting four times the scratch resistance compared to rival aluminosilicate cover glasses.
Another big benefit of the new generation is that it enhances visual clarity by reducing reflectance by up to 75% when contrasted with a standard glass surface, improving display readability.
Is Gorilla Glass Armor that much better?
Most of these claims are exaggerated or put out of the right context. If you look at the table above, you will see that the differences in hardness and fracture resistance aren't that big.
More practical approaches to testing different generations of Gorilla Glass have shown that the scratch and break resistance is somewhat uniform across all generations. Granted, every new generation is marginally better, but the important word here is marginally.
That being said, sometimes small differences in these parameters could be the dividing factor between a broken screen and an unscathed one, so it's, of course, best to have the latest version on your phone.
Gorilla Glass applications
Gorilla Glass is used not only in smartphone displays but also for manufacturing car windshields, windows for residential and business buildings, laptop, monitor, and TV displays, and many other applications where tough and scratch-resistant glass is needed.
Gorilla Glass alternatives
Gorilla Glass is harder than normal glass; it has an index of 6.5 on Moh's mineral hardness scale. The scale spans from 1 to 10, with 1 being talc and 10 being diamond. Gorilla Glass has a hardness of around 7 on Moh's scale, and while it is harder and more durable than normal glass, there are much better (and more expensive) alternatives.
The most popular one is called Sapphire Crystal, and it's basically a synthetic sapphire made in a lab in conditions of extreme heat and pressure. You're probably familiar with Sapphire Crystal, as it is used on luxury watches and lately on some of the high-end smartwatch models.
Sapphire crystal has a hardness of 9 on Moh's scale, and it's almost unscratchable. You'll need a diamond or something at least as hard as a sapphire to make a dent or a scratch on it. So, where's my Corning Sapphire Glass then?
Making large sheets of Sapphire Crystal is difficult and expensive. There are smartphones with Sapphire Crystal coatings; many Kyocera rugged models feature this material, but for the mainstream smartphone market, it's deemed too expensive and overkill. Sapphire Crystal also transmits less light, which means dimmer displays.
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Mariyan, a tech enthusiast with a background in Nuclear Physics and Journalism, brings a unique perspective to PhoneArena. His childhood curiosity for gadgets evolved into a professional passion for technology, leading him to the role of Editor-in-Chief at PCWorld Bulgaria before joining PhoneArena. Mariyan's interests range from mainstream Android and iPhone debates to fringe technologies like graphene batteries and nanotechnology. Off-duty, he enjoys playing his electric guitar, practicing Japanese, and revisiting his love for video games and Haruki Murakami's works.
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