Behind the Scenes Look at Corning’s Gorilla® Glass

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uBreakiFix was recently invited to tour Corning’s research and testing facilities in Corning, NY, where Gorilla® Glass is tested and analyzed. Our tour included a behind the scenes look at Corning Testing Labs with some of the engineers responsible for designing the latest and greatest Gorilla® Glass.

 

Gorilla® Glass is a widely popular choice for modern smartphone and tablet manufacturers, including Samsung, HTC and Apple. In fact, Gorilla® Glass can be found on over 3 billion devices worldwide! So what makes Gorilla Glass such a popular choice, and what sets it apart from other glass on the market? Corning’s answer is simple. The secret to their success lies in what they call “Retained Strength” and “Damage Resistance.” We’ll dive into this subject more in a minute, but it’s interesting to note that Corning’s “Damage Resistance” combined with a  chemical tempering process creates a surprisingly strong and resilient product.  After our facilities tour, we put Gorilla® Glass to the test to verify Corning’s claims. Check out the video below to see what we discovered.

 

So what is Chemical Tempering and Damage Resistance? 

Corning set out to make the electronics industry’s strongest cover glass, and the process starts with something called “ion exchange,” a method of chemically tempering the glass. When the glass on your smartphone shatters, it is the result of tension forces, not compression. So in the tempering process, the glass is essentially “pre-stressed” in compression. This is done by exchanging sodium ions with larger potassium ions. This means any tensile stress on the glass must first over come preexisting compression forces. The result is glass that can take much higher forces before failing.

Gorilla® Glass Ion Exchange Process
Gorilla® Glass Ion Exchange Process

 

But the real competitive advantage for Gorilla® Glass is its “Retained Strength.” Corning Engineers reiterated the need for “retained strength” or “damage resistance” many times on our site tour. To understand this principle, we need to understand the science behind broken glass. Glass is only as strong as its weakest imperfection. Scratches, indentations, chips and any other flaws in the glass can significantly weaken the glass, especially as these flaws compile over time. Think of it this way: traditional window glass, or soda lime glass, can withstand a certain amount of bending stress before breaking, and as long as there are no flaws in the glass, this stress can be significant. However, introduce a flaw by scratching the surface of this glass, like we did in the video above, and it will significantly reduce the the stress required to break the glass. The stress required to break a flawed sample can be many times less than the original strength, depending on the flaw. In fact, the easiest way to “cut” glass during manufacturing is to “score” or scratch the glass and then apply a bending force.

 

DSC_0249

 

Due to Corning’s proprietary manufacturing process, flaws and scratches experienced during everyday use are not nearly as debilitating to Gorilla® Glass as they are to more traditional glass. This superior “Retained Strength”  is what Corning calls “Damage Resistance.” Our independent testing revealed an 83% strength reduction in scratched traditional glass compared to flawless traditional glass. The same test performed on Gorilla® Glass resulted in only a 17% strength reduction. That’s pretty impressive given the surface flaws we were dealing with. Check out the video above to see more.

 

How Corning Tests Gorilla Glass

See the various strength and durability tests we saw first hand in Corning’s tests labs.

 

Corning’s testing and research labs are home to dozens of tests designed to demonstrate the strength and durability of Gorilla® Glass.

 

Tests Performed in Corning's Strength Lab
Tests Performed in Corning’s Strength Lab

 

Four Point Bend Test- Designed to test edge strength, the 4-point bend test loads the sample along two parallel top inner rollers, while supporting the sample along two parallel outer rollers. We are always amazed by how much glass can bend.

 

4-Point Bend Test
4-Point Bend Test

 

Indention and Scratch Test– These tests are designed to demonstrate damage resistance. Using a diamond indenting tool or “scratch head,” samples are indented or scratched using increasing pressure. The entire process is viewed by a microscope at 20x magnification or more.  Here the difference between Gorilla® Glass and tradition soda lime glass is clear. While Gorilla® Glass sustained the scratch or indention with out much collateral damage, the traditional glass sample showed dozens of micro fractures exploding around the scratch or indention site.

 

Indention Test- Test sample shown is traditional soda-lime glass
Indention Test- Test sample shown is traditional soda-lime glass

 

Device Drop Test– This test is designed to test real world drop scenarios. Devices or sample “pucks” with cover glass are dropped in a variety of orientations on a variety of surfaces. The tests are filmed at high speed to allow engineers to analyze damage scenarios.

 

Device Drop Test- The sample shown is a test "puck" with curved  surface Gorilla® Glass adhered to the bottom surface
Device Drop Test- The Sample shown is a test “puck” with curved surface gorilla glass adhered to the bottom surface

 

Ball Drop Test– This test applies surface stress that glass may experience during impact. This is done by dropping a steel ball from various heights onto glass samples.

 

Ball Drop Test- The sample shown is Gorilla Glass, and it withstood a drop from this height with no visible damage
Ball Drop Test- The sample shown is Gorilla® Glass, and it withstood a drop from this height with no visible damage.

Corning’s Fractology Lab

In addition to the testing labs, Corning gave us a behind the scenes tour of their fractology lab. This is where Corning Engineers reverse engineer broken samples to find crack origin, surface or failure patterns, crack propagation direction and much more. Corning uses this information to better engineer future products.

 

Cross section of a cracked sample showing the crack origin
Cross section of a cracked sample showing the crack origin

 

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Cross section of a cracked sample showing crack propagation from the origin

 

The Future For Corning

Corning believes the future of the cover material for electronic devices is glass. They don’t see any material on the horizon that can compete with the versatility and usefulness of glass. Our visit to Corning included a conversation on the material properties of Sapphire, and its demonstrated lack of retained strength.

 

Cracked sapphire cover material sample
Cracked Sapphire Cover Material Sample

 

Corning is currently developing more iterations of stronger and more reliable Gorilla® Glass. Additionally, they are experimenting with shaped and curved glass as well as new forms of functional coatings for cover glass.

 

Curved Gorilla Glass
Curved Gorilla Glass

 

A huge thanks to the entire team at Corning for the inside look at the labs.

 

As always, stay tuned for more uBreakiFix Learn!

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