By testing glass in its "flaw-free" form, researchers at the University of Missouri-Rolla have found a common commercial glass to be more than one and a half times stronger than was previously thought.
One of the key researchers, Nate Lower, a Ph.D. student in ceramic engineering at UMR, developed the testing technique with the help from his two brothers, Lucas and Trent, who are tool-and-die makers. "Glass is extremely complex and strength is difficult to predict and you want to be able to verify this through testing," Lower says. "We are able to test pristine samples and measure its intrinsic strength." Lower’s brothers constructed the specialized equipment used in the experiment.
"Nate has developed a technique to produce glass fibers that are untouched and pristine," says Richard Brow, chair and professor of ceramic engineering. "This makes it easier to test a fiber’s strength without damaging it. Glass breaks at its weakest link and the act of touching it causes damage."
The glass fibers — each about the same thickness as a human hair — are pulled upward from a crucible holding the glass melt in a blazing furnace and attached to a machine that resembles a carnival’s Ferris wheel. The wheel is then turned, pulling glass fibers out of the furnace and securely wrapping them around the wheel without touching one another. This is how flawless glass is produced. From here, researchers can test sections of it for strength by bending the single fibers into a "U" shape and pressing them between two metal plates until the fiber breaks.
By knowing more about the strength of glass fibers, manufacturers will be able to improve production, says Brow. This method would be also be economic and easy to for the industry to implement. The National Science Foundation’s Industry-University Center for Glass Research is supporting these research efforts. Other researchers involved in this effort include Prabhat K. Gupta, professor of materials and science engineering at Ohio State University, and C.R. Kurkjian formerly of AT&T Bell Labs and now a visiting professor of ceramic and materials engineering at Rutgers University.