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Everything You Need To Know To Find The Best is glass strong

Feb. 04, 2024
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Glass Stronger than Steel

Enlarge Photo

Image courtesy of R. Ritchie and M. Demetriou

Highly magnified image shows a sharp crack introduced into palladium-based metallic glass and the extensive plastic shielding, marked by the white shear lines extending out from the crack, prevent the crack from opening the glass any further. Inset is a magnified view of the shear lines (arrow) developed during plastic sliding.

Drop a glass and it breaks, right? But there's a kind of glass that while not exactly unbreakable, can be unusually strong. It's not transparent, and it's actually made of metal, but it's a "glass" in the technical sense—that is, a solid whose underlying structure resembles that of a liquid. These so-called "metallic glasses" are among the more interesting and useful new materials devised by modern materials scientists, and they possess valuable mechanical, electrical, and magnetic properties.

Now a collaboration of researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the California Institute of Technology (Caltech) has just produced a new version of metallic glass that is stronger and tougher than steel, or any other known material. What's more, even better versions of this new glass may be on the way.

Glassy materials have a non-crystalline, amorphous structure that makes them inherently strong but invariably brittle. Whereas the crystalline structure of metals can provide microstructural obstacles (inclusions, grain boundaries, etc.,) that inhibit cracks from propagating, there's nothing in the amorphous structure of a glass to stop crack propagation.

The problem is especially acute in metallic glasses, where single shear bands can form and extend throughout the material leading to catastrophic failures at vanishingly small strains. The new metallic glass is a microalloy featuring palladium, a metal that counteracts the intrinsic brittleness of glassy materials. It marks the first use of a new strategy for metallic glass fabrication that should yield even stronger and tougher glass in the future, according to Robert Ritchie, a Berkeley Lab materials scientist who led the Berkeley contribution to this research.

"In our new palladium-containing glass, the energy needed to form shear bands is much lower than the energy required to turn these shear bands into cracks," Ritchie says. "The result is that our glass undergoes extensive plasticity in response to stress, allowing it to bend rather than crack."

Ritchie, who holds joint appointments with Berkeley Lab's Materials Sciences Division and the University of California (UC) Berkeley's Materials Science and Engineering Department, knows a lot about strong and tough materials. Two years ago, he and his research group mimicked the structure of mother of pearl to create what may well be the toughest ceramic ever produced. Through the controlled freezing of suspensions in water of an aluminum oxide (alumina) and the addition of a well known polymer, polymethylmethacrylate (PMMA), they produced ceramics that are 300 times tougher than their constituent components. Prior to that, he and his group had undertaken a study to determine why the bones of elderly people are more prone to fractures than the bones of younger people.

Using state-of-the-art imaging, testing techniques, and detailed mechanical analysis, they learned that as people grow older, their bones lose their ability to resist the formation and growth of cracks that lead to breaks.

This earlier research in material strength and toughness paved the way for the investigations into metallic glass. The first metallic glass fabricated by the Berkeley-Cal Tech collaboration was dubbed "DH3."

In DH3, the propagation of cracks was blocked by the introduction of a second, crystalline phase of the metal. This crystalline phase, which took the form of dendritic patterns permeating the amorphous structure of the glass, erected microstructural barriers to prevent an opened crack from spreading. Now the collaboration has produced a pure glass material whose unique chemical composition acts to promote extensive plasticity through the formation of multiple shear bands before the bands turn into cracks.

"Our game is to try and extend this approach of inducing extensive plasticity prior to fracture to other metallic glasses through changes in composition," Ritchie says. "The addition of the palladium provides our amorphous material with an unusual capacity for extensive plastic shielding ahead of an opening crack. This promotes a fracture toughness comparable to those of the toughest materials known. The rare combination of toughness and strength, or damage tolerance, extends beyond the benchmark ranges established by the toughest and strongest materials known."

The initial samples of the new metallic glass were microalloys of palladium with phosphorous, silicon and germanium that yielded glass rods approximately one millimeter in diameter. Adding silver to the mix enabled the Cal Tech researchers to expand the thickness of the glass rods to six millimeters. The size of the metallic glass is limited by the need to rapidly cool or "quench" the liquid metals for the final amorphous structure.

"The rule of thumb is that to make a metallic glass we need to have at least five elements so that when we quench the material, it doesn't know what crystal structure to form and defaults to amorphous," Ritchie says. "Traditionally strength and toughness have been mutually exclusive properties in materials, which make these new metallic glasses so intellectually exciting. We're bucking the trend and pushing the envelope of the damage tolerance that's accessible to a structural metal."

While the most immediate applications of this new metallic glass are likely to be in the electronics industry, or in medical devices, such as orthodontics or spinal implants, Ritchie envisions a future in which metallic glass could be used in airplane engines or large structures, such as bridges. Metallic glass might eventually even be used to make stronger and tougher containment vessels for nuclear reactors that would be more resistant to catastrophic failure.

"This metallic glass is probably the best damage-tolerant material we've ever seen," he says.

—Lynn Yarris, Lawrence Berkeley National Laboratory, lcyarris@lbl.gov

Funding

Characterization and testing research at Berkeley Lab: DOE Office of Science, Office of Basic Energy Sciences

Fabrication work at Cal Tech: National Science Foundation

Publication

M.D.Demetriou et al. "A damage-tolerant glass," Nature Materials 10 123 (2011).

Related Links

For more information on the research of Robert Ritchie, visit the Website at
http://www.lbl.gov/ritchie/

For more information on the research of William Johnson visit the Website at
http://www.its.caltech.edu/~vitreloy/index.htm

Your Guide to Tempered Glass

Glass is a consistent component of any household structure. It’s a crucial makeup of our windows, doors, and sometimes even walls and ceilings. Therefore, the type of glass used is often a key factor to consider in many home renovations. When considering a door or window renovation, you’ll definitely need to account for the fact that you may be required (and certainly want) to use what is known as tempered glass.

Here at AVI Windows and Doors, we have the know-how and expertise to help you understand what tempered glass is and where and how to best install tempered glass in your home. Here is a brief guide to what tempered glass is, what is does, why you need it in your home, and where you should consider installing it in your next home renovation.

Key Takeaways:

  • Tempered glass is created after the glass is heated rapidly, followed by immediate cooling
  • Tempered glass is nearly five times stronger than standard glass, making it less likely to shatter
  • Because tempered glass is more durable than standard glass, it is considered to be safer and is often placed in high traffic areas
  • According to International Residential Code, tempered glass must be used for swinging, sliding, operable, fixed, or bifold doors

What is Tempered Glass?

First, let’s understand what tempered glass is and why you need it in your home. Face it: glass is a material prone to breaking. Tempered glass, however, is a glass that is treated to be roughly five times stronger than standard glass. It is not unbreakable of course, but when tempered glass is shattered, it turns into small square pieces that are less like to pose a safety hazard. Logically speaking, if glass is going to break, there are places in the home where it is much safer to have this type of shattering occur, such as a highly trafficked doorway or in the bathroom.

How is Tempered Glass Made?

Tempered glass is created by rapid heating of the glass followed by immediate cooling, thus giving the glass a stronger composition and changing the way it breaks.

Where does Tempered glass go in the household?

Where tempered glass goes in your household will certainly be determined by where you are considering safety a high priority, and there are already even international standards of where tempered glass must go. In fact, some states have even stricter regulations.

Benefits of Tempered Glass

As mentioned above, tempered glass is significantly more durable than other types of glass such as annealed, or standard glass. Therefore, it is also a much sounder investment, as while more expensive than annealed glass, tempered glass durability makes it pay off in the long run. Furthermore, when glass such as annealed breaks, it creates jagged and sharp shards that shatter everywhere. So, when safety is a top priority, such as in a highly trafficked area or a place where slipping and falling is more probable, you need to consider tempered glass.

Tempered Glass in Doors

According to what is known as the International Residential Code, all glass and panels must be tempered in these types of doors: swinging, sliding, operable, fixed, and bifold. This is true regardless of panel size. Furthermore, you must temper any glass within 24 inches of a door with its bottom edge less than five feet above said door. As mentioned before, some states in the US have stricter codes.

Tempered Glass in Windows

Likewise, tempered glass must be used in a window under certain circumstances. For instance, it must be included when all the following criteria are met:

  • The window measures 9 square feet or more
  • Its bottom edge is less than 18 inches from the floor and its top edge is more than 36 inches above the floor
  • There’s a walkway within 36 inches on either side

Furthermore, tempered glass must be used when the glass is next to stairs, landings, and ramps that are within 36 inches of a walkway and if glass is less than 60 inches above.

Using Tempered Glass in Wet Areas

Obviously, bathrooms, saunas, hot tubs, and the like are places in a home where the moist nature of the location can create a natural hazard. Because of the danger of slipping and falling, these types of rooms also have codes and requirements for tempered glass. If a glass’ bottom edge is less than 60 inches above a walking or standing surface (like a shower floor), then the glass must be tempered. Moreover, for a hot tub, glass must be tempered if its bottom edge is less than 60 inches above the walkway and less than 60 inches from the water’s edge.

AVI Has Got Your Windows and Doors with Tempered Glass

For your next home renovation, AVI has got you covered for all your tempered glass needs. Our in-person and online expertise can help guide you on choosing the right tempered glass in your next window or door installation that adheres to any and all codes and regulations. Whether online or in person, we are your one stop shop to view, choose, and install your next window or doors with tempered glass.

Don’t hesitate to reach out to us online, by phone, or at one of our southeast locations. We can’t wait to hear from you and join you in your next home renovation!

Interested in learning about other glass types?

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Everything You Need To Know To Find The Best is glass strong

Your Guide to Tempered Glass

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