Gorilla Glass 3 explained (and it is a modeling first for Corning!)Published on January 7th, 2013 | By: Peter Wray
Credit: Corning; YouTube.
[updated with link to Corning's new GG3 product information sheet] Among techies (amateur and professional), Gorilla Glass has developed a cult following. Even my barber, who was only vaguely aware of my occupation, once gave me a long rap about the stuff, and I figure that when a topic reaches the barbershop level, then it has truly found a niche in pop culture (in part, explainable by the penetration of iPhones and iPads). My barber even tracked the introduction of Gorilla Glass 2 and peppered me with questions about it, and I did my best to explain how it was essentially an optimized version of the original GG. Now, however, when I go in for my hair cut next week, I am going to have to explain how Gorilla Glass 3 (PDF), which is being introduced this week at CES, represents something truly revolutionary, not only in terms of composition, but also because Corning has hit a home run with its first foray into developing a glass product based on advanced computational modeling techniques.
One part of the public’s fascination with GG is the story of how Steve Jobs got Corning’s Wendell Weeks to dust off a type of strong, thin, orphaned glass material that had been shelved by the company for lack of a market. Jobs and Apple ended up with the iPad/iPhone sensation, and Corning suddenly had a goose laying golden eggs and a technology that made a relatively pedestrian glass company into a tech superstar. Not only did GG make Corning shareholders happy ($1 billion in sales of something not sold five years ago), but it also seemed to stimulate a new set of strategic visions and values internally. Suddenly Corning was also unveiling other advanced glass products, including glasses that are so flexible and durable that they could be used in roll-to-roll processing. Willow Glass and Lotus Glass could allow low-cost backplane TFT electronics, with the latter opening the door to Retina Display-class resolutions for phones and tables.
I don’t want to come off as implying that, prior to GG, Corning was a stranger to advanced glass technologies. In fact, the company has always done pioneering work in developing optical fiber technology and products, and had developed a revolutionary “fusion” continuous production system that also gave it a big advantage over competitors.
Corning also has had the good sense to hire talented researchers and consultants into its R&D stable, a smart move because once the company started to travel in the same circles as the Apples, Samsungs, Microsofts of the tech world, innovation and R&D are enormously important. As a supplier, not a retailer, Corning’s role in the broad value chain is to be able to hear what materials and material properties manufacturers (and consumers) are looking for, and then quickly translate that into potential applications that meet functionality and manufacturing requirements. Thus, despite the fact that GG1&2 performed qualitatively better and were more cost-effective than anything else available, manufacturers and consumers wanted a cover glass that was even more shatter and scratch resistant.
The problem was that the original GG composition had been optimized about as far as it could be. What was Corning to do? One dilemma for Corning, as with all materials development companies, was that new materials traditionally take years, if not decades, to develop and test. To slash R&D timeframes, Corning (and many others) increasingly open up to shifting from trial-and-error benchtop methods to predictive computational modeling approaches.
Enter, John Mauro, a young Corning researcher, who only earned his PhD in glass science in 2006 from Alfred University. I first met Mauro around 2008, and it was easy to discern that he is very sharp, is a prolific reader, loves glass discussions, and learned all he could from some of the best veteran glass scientists around, such as A.K. Varshneya and P.K. Gupta. Two years ago, Mauro approached me because he wanted to write an overview story for ACerS Bulletin magazine about “the topological constraint theory” of glass. I admit that, at first, this seemed like an esoteric topic, but Mauro argued that if the current “big thing” for materials development is computational modeling, then topological constraint theory is going to be the go-to modeling framework for glass scientists and engineers. Indeed, one of Mauro’s concluding comments in the article we published was, “Topological constraint theory is arguably the most powerful tool available to predict the relationship between composition and structure of glass and its measurable properties.”
In brief, topological constraint theory provides something of a shortcut for modeling and is largely attributable to the work of J.C. Phillips in 1979 (but has been elaborated on by many others). The theory is that, in many ways, glass’ macroscopic performance can be understood just by looking at a narrow portion of the microscopic physics involved with its thermal, mechanical, and rheological properties.
If the theory is accurate, the implication is that materials developers do not have to wait years (or decades) for the computational power that would be required to conduct simulations based on direct molecular dynamics. Instead, the theory suggests there would be enormous benefits from a simpler modeling approach that narrowly focuses only on the key physics that governs the bond constraints of glassy materials. As Mauro wrote in the Bulletin, “One cannot help but be excited by the future prospects of this approach, which is poised to make computational design of new glass materials a reality.”
I should have realized that Mauro was thinking about this topic for practical reasons, and it turns out that Mauro led the research effort on Gorilla Glass 3 and is at CES to assist with its official release.
In an email to me, Mauro provides this exclusive explanation of GG3, an innovation that he is obviously proud of and excited about. He reports that although the new glass has been chemically strengthened via ion exchange (a method that toughens glass by “packing” and compressing the surface layers by swapping smaller ions with larger ones), Mauro writes that it is much more than an incremental improvement.
Gorilla Glass 3 inherits all of the advantages of Gorilla Glass 2 in terms of maximizing the level of surface compressive stress via the ion exchange process, and, in addition to this, it introduces a new feature that we are calling “Native Damage Resistance.” Even with exactly the same ion exchange conditions as Gorilla Glass 2, the new Gorilla Glass 3 enables three times the damage resistance, which is quantified either through a Vickers scratch test or a Vickers indentation threshold (basically how much load is required to initiate a crack).
How does this work? An applied load imparts a large amount of energy on a material, and the material needs to respond to this energy. Beyond the elastic limit, a brittle material such as a glass or ceramic would normally dissipate this energy through formation of new surfaces (via crack formation). This is what all chemically strengthened glasses have done up to this point. But with Gorilla Glass 3, we have developed a glass that has more constructive ways of dissipating energy, namely, through localized densification around the indenter. With Native Damage Resistance… it takes three times the force before cracks pop in. Since retained strength is limited by these cracks, there is a clear advantage in Gorilla Glass 3. Also, this represents a major improvement from an aesthetic point of view, since cracks are suppressed.
Where did the topological constraint modeling come into the process? Mauro writes,
Native Damage Resistance is the result of our newly designed glass composition. We literally started at the atomic level with this one with the goal of designing a uniquely optimized glass structure. We did this based largely on topological constraint theory… In fact, this is Corning’s first glass composition to be optimized exclusively through modeling before anything was melted in the lab. Subsequent experimental work proved that the composition predicted to be the best glass through topological modeling was indeed the most optimal. It’s really a breakthrough in compositional design…and that’s what became Gorilla Glass 3!
Although still early in his career, Mauro has already won several international awards including the International Commission on Glass‘ 2010 Woldemar A. Weyl International Glass Science Award and the 2011 V. Gottardi Prize, and the UK Society of Glass Technology’s Sir Alastair Pilkington Award. (ACerS’ Glass & Optical Materials Division also had the foresight in 2006 to give Mauro its Norbert J. Kreidl Award for Young Scholars.)
I think that it is clear that while the work that led up to the introduction of GG3 is a huge leap for Corning, it moreover is a giant vote of confidence and confirmation of the benefits of topological constraint theory modeling for all glass researchers.
Perhaps we will learn more tomorrow. James P. Clappin, president of Corning Glass Technologies will participate Tuesday in a CES panel, “Disruptive Technologies Impacting the Future of Games and Video.”
GG may also have a disruptive influence on the auto manufacturing. Corning CFO James Flaws predicted just a few weeks ago that he expects to announce in 2013 an agreement to supply auto glass made “of a version of Gorilla.” He goes on to note that an advantage for automakers is the light weight of the glass, which helps with mileage and lowering the center of gravity.
By the way, for an authoritative look constraint theory, Mauro recommends the book Rigidity and Boolchand Intermediate Phases in Nanomaterials, edited by M. Micoulaut and M. Popescu.
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