quinta-feira, 2 de fevereiro de 2017

How flexible glass for devices of the future comes to life

 

technologyreview.com

 

Katherine Bourzac

A key ingredient in flexible and lightweight devices of the future is taking shape at Corning’s research center in rural New York.

At  Corning’s headquarters in upstate New York, three people in bulky masks and silvery, spacesuit-like gear are working the research furnaces. They move gracefully and in harmony. They have to, to face a 1,600 °C furnace, grab an incandescent crucible of molten glass, pour out the material, and shape it before it hardens. One worker’s glove begins to smoke; he seems to pay it no mind.

“They’re doing a ballet,” says Adam Ellison, a materials scientist at the company, watching the furnace workers as the glass dumps brimstone-like heat into the surrounding air. “It’s hot as hell, the glass gets stiff very quickly, and you can only work with it for a few minutes,” he says. Ellison would know—he helped develop the material they’re pouring, which is branded Gorilla Glass and is found on many smartphones because it is tough, thin, and lightweight.

These researchers are helping Corning investigate just how much further it can push the properties of glass. If the company could make glass that is difficult to scratch and break but also bendy, it could open up entirely new product categories: cell phones and tablets that fold or roll, for example. Thin, flexible glass might also turn curvy surfaces such as car interiors into touch-screen displays.

The research melter team prepares about eight to 12 experimental pours a day, providing samples for company scientists. The scientists want to know what will happen if they try something new, such as melting glass at a different temperature. The team also tests different manufacturing methods to see how they affect glass properties.

Potential new products are subject to every kind of abuse Corning engineers can think of and quantify. One machine repeatedly bends a thin piece of glass to see how long it will hold up; another machine bends glass in two until it shatters with an eardrum-shocking pop. Specialists in fractography—the science of how and why materials like glass fracture—use custom machines to measure the pressure required to fracture glass. With microscopes, researchers study the mechanical messages in the resulting crack pattern. Glass that’s stronger will fracture with a large number of cracks; weaker glass cracks in only a few places. Materials that pass the test might next be made into cell-phone dummies and repeatedly dropped from waist height onto cement, gravel, and other surfaces.

Potential products are subject to every kind of abuse engineers can think of and quantify.

Most of the company’s research is on new manufacturing processes and gradual improvements of existing products like Gorilla Glass. But scientists also get to play around. One of Ellison’s recent projects, for example, was to try to re-create the glass used to make the fourth-century Roman Lycurgus Cup. The goblet is cranberry red when lit from behind and jade green when lit from the front.

Ellison giddily shows off a sample of his Lycurgus-inspired glass, holding it up to a window to demonstrate the effect. “Now I know in detail why it does this,” he says. Since he doesn’t know what use such glass might have today or in the future, though, the recipe will go onto the shelf for a future employee to find.

 

Furnace workers at Corning’s research melters, working in teams, wear silvery “bunny suits” when opening a 1,600 °C oven where experimental glass is melted.

  Workers pour the contents of a crucible of melted glass onto a metal table.

A worker uses scissors to shape the glass into a puck for scientists to study. The glass quickly stiffens and begins to change color as it cools.

  

The fourth-century Roman Lycurgus Cup. New glass that passes muster is tested in a miniature version of the company’s manufacturing line. Glass for displays and cell phones is made in meters-wide sheets; this process makes test glass a few centimeters wide.

  

Under a polarizing lens, colored stripes indicate mechanical strain inside a puck of experimental glass. The iridescence in this sample suggests that it will break easily and that researchers should alter the processing conditions.

  

This machine bends a piece of flexible glass to determine how much stress it can take before it breaks. Researchers can then study the pattern of the fracture to learn how to make the glass more resilient.

 

Corning also develops new processes for handling glass, which can help device makers make custom pieces for new models of electronics.

 

This ultrathin glass spiral was cut with a new laser machining process.

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