Glass that’s Stronger than Steel

Julia Greer, an assistant professor of Materials Science at Caltech, who was not involved with developing the material, says, “it has potential to overcome the limitations the metallic glasses always had.”

The work is outlined in a study published this week in the journal Nature Materials. Marios Demetriou, a professor at Caltech and lead author of the paper, says the work involved finding a particularly strong version of the simplest form of glass, called marginal glass, and then turning it into the even stronger form known as bulk glass.

“What we did here is find a very, very tough marginal glass made of palladium with small fractions of metalloids like phosphorus, silicon, and germanium, which yielded one-millimeter-thick samples. And we just said, let’s add very little of something that will make it bulk without making it brittle,” says Demetriou. By adding 3.5 percent silver to this marginal glass, Demetriou was able to increase the thickness to six millimeters while maintaining its toughness.

“The Achilles’ heel of these metallic glasses is that when you pull them in tension or try to deform them somehow, they fail catastrophically,” says Greer. This occurs through the formation of what’s termed “shear bands,” small defects which coalesce into vein-like patterns that rapidly evolve as cracks, causing the glass to break under extremely small strains. However, according to the researchers, the palladium glass generates so many of these bands that they form a blocking pattern that prevents cracks from propagating without impairing the material’s overall properties.

Ritchie says it may be possible to combine other elements to make even better glasses. John Lewandowski, a professor of metallurgy at Case Western Reserve University, says, “One of the results from this project will be to spur a lot of work in related areas, examining the details, modeling it, analyzing temperature effects or what happens when you test it.”

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The limitation is palladium’s very high cost. Therefore, Ritchie says, although there are countless structural applications that could utilize this material’s high strength and toughness—like automotive and aerospace components—many of them will prove impractical in the marketplace.

Demetriou is more optimistic. He believes there’s already demand for metallic glass and says a product like a dental implant made from the stuff could be available within the next five years. He says this would offer a “superior alternative” to traditional implants made of noble metals, which are softer and stiffer and thus more likely to wear or cause bone atrophy.

The first step is convincing a manufacturer that the material possesses “unique and unusual attributes,” he says. Then a series of tests of its performance, longevity, and biological compatibility will be needed before ultimately determining whether the pricing would be competitive.

As for making large-scale structures like bridges, Demetriou says cost would probably prevent that. But he has hopes of developing something cheaper. “If we develop an iron or copper alloy with these properties,” he says, “I’ll tell you this: we will put steel out of business forever.”

Which Window Glass is Best for Your Area?

If you live in a colder climate, you want to minimize heat escaping your home and maximize radiant heat from the sun entering your home in the winter months, which means a lower U-Factor and higher SHGC.*

If you live in a warmer climate, heat escaping your home is not as important as preventing the sun’s radiant heat from entering, which means a higher U-Factor and lower SHGC.

There are additional factors when

The bottom line for glass performance is this: When building a new home or replacing windows in your existing home, make sure to have a conversation with the installation contractor or

If you live in a colder climate, you want to minimize heat escaping your home and maximize radiant heat from the sun entering your home in the winter months, which means a lower U-Factor and higher SHGC.*If you live in a warmer climate, heat escaping your home is not as important as preventing the sun’s radiant heat from entering, which means a higher U-Factor and lower SHGC.There are additional factors when considering Low E coatings . If you want to protect grandma’s family heirloom or a valuable art collection, you may want to add specific coatings that will reduce the harmful effects of UV radiation, even if you live in a cold climate. In far northern climates the sun will not shine directly through windows located on the north side of the building, so it may be unnecessary to install windows with a high SHGC to take advantage of the warm sun rays. Large shade trees can reduce the need for windows with a low SHGC. If perfectly clear glass is important to you, remember that the more coatings you apply to a window, the more tint it will have.The bottom line for glass performance is this: When building a new home or replacing windows in your existing home, make sure to have a conversation with the installation contractor or window dealer . Let them know which glass characteristics are most important to you.

*In northern climates it’s sort of a “pick your poison” when it comes to SHGC. If you choose a window with a low SHGC, you could benefit from the sun’s heat in the winter, but you also may have to manage the heat from the summer sun with shades, large overhangs, shade trees, etc.