Gorilla Glass was developed by Corning as a scratch-resistant and durable alternative to regular glass for use in mobile device screens. It has desirable properties such as high flexibility, strength, and chemical durability. Gorilla Glass's microstructure is similar to regular glass but contains larger potassium ions just below its surface, which induce compressive stress to increase strength and durability without increasing thickness or density. It is manufactured through an ion exchange and fusion forming process that results in an exceptionally thin and smooth glass coating.

1. Oliver Webb - 701

2. Requirements for a good screen coating
• Resistant to shattering
• Smooth to allow for easy and comfortable use
• Hard surface meaning it doesn’t scratch easily
• Highly transparent to avoid a blurred or dark image on the
screen
• High chemical durability to avoid damage from spillages
• Thin to allow capacitive touchscreens to remain responsive

3. Microstructure
• The microstructure of Gorilla Glass is
greatly similar to that of Soda Lime
(common) glass, the main difference is
the layer of Potassium Nitrate ions on
the exposed surface and a thin layer
below it. The crystal structure remains
the same in this layer, however, the
molecules are overall larger. Corning do
not provide any pictures showing the
microstructure of their glass, but it is
almost identical to that of the Alumina-
zirconia-silica glass shown on the right.

4. Gorilla glass was developed by Corning as an alternative to plastic or regular glass screens
on mobile phones, tablets, laptops, and TVs. The main purpose of gorilla glass was to stop
the increasing chance of cracking your screen when your phone gets dropped. It is
incredibly scratch resistant compared to normal glass that is made primarily from Silicon
Dioxide (SiO2).
Its other desirable properties include:
• A low friction surface
• High Flexibility
• Much better strength to mass ratio than regular glass
Figure B shows Gorilla Glass, notice how much less cracking there is
compared to the soda lime glass in figure A.
Two heavy metal balls placed on a sheet of Gorilla Glass.
If regular glass were used, it’d break due to its lower
flexural strength.

5. Size and density compared to SiO2 Glass
• The 4th and latest generation of Gorilla Glass is the
lightest and thinnest version to be manufactured yet.
Its thickness on the just-released Samsung Galaxy A7
was only 0.4mm or 400 microns. It is incredibly
difficult to get regular glass to this thickness without
sacrificing strength and its already limited resistance
to strain. It has a density of 2.42gcm-3. The density of
SiO2 varies depending on other materials used but is
generally somewhere between 2.4 and 2.8gcm-3
making it about the same density as gorilla glass.
Although their densities are similar, Gorilla Glass
achieves much greater strength and durability with
the same volume of material.

6. Manufacturing process
• Gorilla Glass is made from an alkali-aluminosilicate which is created
via ion exchange. This material is submerged in a molten alkaline
potassium salt. To melt this salt temperatures of about 500°C
(930°F) are required. When molten, the ions in the salt are able to
move freely. Potassium ions are much larger than the sodium ions
present in the material before it’s submerged. The larger potassium
ions replace the sodium ions which means there is less empty space
in the newly formed sheet of glass. By occupying more space, a layer
of high residual compressive stress is created at the surface which is
mostly what gives Gorilla Glass its highly useful and desirable
properties. This is also combined with a process called “fusion
forming”, a proprietary method used by Corning. This involves taking
the high quality raw material, making it into molten glass at
temperatures above 1000°C, pushing it through an isopipe (a
specialised metal pipe that acts as a thermal insulator for the glass
flowing through it), then letting it evenly flow over both sides of the
specially shaped container they use. This allows Corning to make
exceptionally thin glass with a very smooth finish which is essential
for glass coatings on touchscreens.

7. Chemical Durability
• Sheets of Gorilla Glass were
submerged in various solvents
to measure how much mass
was lost after different
periods of time. As you can
see from the table, even in
very extreme conditions such
as exposure to Hydrochloric
acid at high temperature for a
long period of time, only
around 36% of mass was lost.
Judging by how little effect
these chemicals had on loss of
mass, they shouldn’t become
damaged under any normal
conditions.

8. Hardness
• A high measure of hardness means that
a material can withstand a lot of force
before becoming scratched. As can be
seen in the picture, even at a relatively
high force of 4.00 newtons, no easily
visible scratch has been made in the
Gorilla Glass. However, in the two oher
types of glass on show, large amounts of
damage. There is noticeable fracturing,
particularly in the regular Soda Lime
glass. This shows that Gorilla Glass must
be much harder and therefore much
better suited to its intended purpose
than other forms of glass. The value
Corning give for its Vickers Hardness is
596 kgf/mm2 for the strengthened glass
and 489 kgf/mm2 for the un-
strengthened glass.

9. Summary
• Gorilla Glass meets all special
requirements for its use. It is
hard, chemically durable, thin,
smooth and tough. These all
make it ideal for use on mobile
phones, tablets, and other
electronics. Corning are
continuing development on
Gorilla Glass so that they can
further improve on the
revolutionary material they’ve
already created.