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July 13th, 2009

ACerS Members Featured in NY Times Glass-Strength Story

The New York Times has discovered materials science! The newspaper recently published a nice story
on the scientific advancements being made to strengthen glass for the
ever expanding use of the material in architecture. The newspaper used the opening of the all-glass “Ledge” recently added for tourists to the Sears Tower in Chicago to discuss advancements being made to strengthen glass.


The glass gurus
interviewed include ACerS members Harrie Stevens, director of the Center for Glass Research at Alfred University, Carlo Pantano, professor of materials science at Penn State and William LaCourse, professor at Alfred.


Stevens, Pantano and LaCourse

Stevens provided some historic perspective for the NYT report, noting that, “For years, the basic composition of soda-lime glass has not changed much,” he said, but went on to explain that, “you can modify the composition to make it innately stronger.”

Pantano explained some of the problems dealing with defects in glass. “That’s what makes glass break,” he said. “And if it doesn’t break, it weakens it.”

The explanation of heat tempering was left up to LaCourse. “Inside it’s still hot, and tries to cool to a more dense structure,” he said. “This pulls the surface into compression.”

Pantano said he enjoyed the article.. “It really did a good job of explaining some fundamental components of glass science,” he said. “We know the public has basic questions and misunderstandings about glass, and it cleared up some of their misconceptions. And, the article helped communicate that researchers are actively working on methods to strengthen the material.”

Stevens agreed with Pantano, saying, “To me, glass is still a fascinating material, so I was thrilled to the story. I was also thrilled to see it was picked up by so many other newspapers and appeared around the country.”


Tempered glass may take longer to crack, but it can still break. A
primary concern when building with glass is what happens if and when a
component breaks. That’s where lamination comes in. In a typical
project, multiple glass sheets (one-half-inch thick in the Sears Tower project)
are bonded with thin polymer interlayers. The interlayers add strength
and, should one of the glass layers break, keep the structure together,
and the pieces from falling.


Arun Varshneya,
also from Alfred, recently spoke with ACerS about the advantages of an
alternative to heat-treated glass: chemically strengthened glass. This
seven-minute interview can be seen here.

Already, some engineers are using different glass shapes to reduce
the dependence on metal. Other designers think about using different
kinds of glass. Using a glass that does not expand much when heated,
for example, would enable components to be welded together, forming, in
effect, a continuous piece of glass. Conventional soda-lime glass
expands too much, so welding introduces stresses that can lead to
failure.


Researchers have experimented with welding glass components.
But low-expansion glass is much costlier than soda-lime glass. Other
engineers are starting to use adhesives to join glass directly to glass.


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