tempered glass can bend before it breaks.

by:JinYi     2020-03-30
When the car window is hit, it will not only break, it will break into tiny, round, harmless pieces.
Because the glass is tempered with heat, the glass will experience this dramatic failure.
Tempering makes the glass very strong, but once the crack starts, the glass breaks into pieces. Now, David J.
Green at Penn State College, Rajan Tandon at the Peoria Caterpillar technology center, is ill.
And Vincenzo M.
Sglava at the University of tresdo in Italy has developed a method of chemically regulating the glass so that it can withstand some cracking before it finally breaks.
\"This is very useful,\" said Green . \"
\"It will give you a little warning before it fails.
\"In addition, the strength of the new glass is easier to predict than the strength of the ordinary tempered glass.
The strength of the traditionally treated glass may vary by 20% from one piece to the other.
However, the strength of the new glass deviates only 2%.
This precision opens up new applications for ceramics, including glass, S said.
Jill Grasse, Sandia National Laboratory in AlbuquerqueM.
\"Designers of different products are reluctant to use ceramics because they cannot predict accurately [the materials]
\"I will go bankrupt,\" she said . \"
For the sake of safety, engineers often over-design the product to make the components unnecessarily thick and heavy.
All tempered glass gets its tendency of high strength and explosive crushing from the force between its atoms.
Those who are outside are gathered together, while those who are deep in the glass are still under no pressure.
Defects are not easy to break through the outer layer, so only very strong blows can cause cracks.
The release of pressure triggered a spectacular break.
Green, Denton, and sgerawo argue that changing this internal stress distribution may change the way glass splits.
They compress the atoms to about 25 microns below the surface, where they can act as a barrier to blocking crack expansion starting from the surface.
The researchers completed the one or two use of this fire sheet sodium aluminum silicate glass.
Chemical process steps.
First, they changed some of the sodium ions in the glass to potassium ions.
Large potassium ions enter the space where sodium is vacated, creating pressure stress in the glass.
The researchers then re-inserted sodium ions only on the surface layer, leaving a tempered layer under the untempered skin.
When the processed sample is bent, many small cracks appear on the skin, extending down to the barrier and then stopping.
The cracks continued to expand until the glass finally broke into small pieces.
This delayed crushing is very unusual in fragile materials, says Green.
The panel described the findings of the February. 26 Science.
Because the technology is relatively expensive, \"it may not take over the field, but it will have applications, Green said.
\"Electronic components may be the first product made of these materials.
In addition, the valves designed to burst open at a certain pressure can be used by Glass.
Green is not sure if this process can be used for windows and windshields as they are tempered with heat rather than chemicals.
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