Have you ever wondered why wine glasses break to pieces on impact? Or was there a moment of fear that the glass walls of the building would break and fall? The structure of glass is very complicated. It's hard and strong, but at the same time it's fragile. For something so common, the science behind broken glass is also complex.
Why does glass break?
In fact, the reason why glass is so easy to break is because of its molecular structure. Glass is made of silica. Silica forms a rigid, random molecular network. Unlike most solids, where the molecules are neatly stacked in a lattice. The silicon and oxygen atoms in the glass are connected at random angles in an irregular pattern.
This disordered arrangement gives the glass transparency and is easy to shape into different shapes when heated. However, this also means that there are no weak spots. As a result, when external pressure is applied, the glass will break in a jagged, uncontrolled manner. Any small surface defect or scratch can also become a stress concentrator. Once a crack is triggered, it quickly spreads throughout the material.
When cracks start to spread, they are hard to stop. Even though the bond between the silicon and oxygen atoms is strong. But it is difficult for the crack to change direction or stop at the edge of the defect. Due to the irregular geometry of the silico-oxygen bonds, they will simply continue to pass through the random network. Glass lacks an orderly structure, so it's hard to predict when it breaks. For the same reason, glass can easily break spontaneously without much warning.
The only way to improve the impact resistance of glass is to introduce a more ordered molecular arrangement. Just like the safety of tempered glass is high, it is because its molecular arrangement is ordered. By rapidly heating and then rapidly cooling, compressive stress can be created inside the glass. These stresses help to counteract the spread of the crack. So tempered glass can withstand a higher load. But that doesn't mean it can't break. It just breaks in a safer form. That is, it breaks into small particles, rather than the sharp pieces of ordinary glass.
Why does heat break glass?
Glass will break except when impacted by external forces. It also breaks when subjected to thermal stress. In high temperature environments, the imbalance of temperature causes the glass to expand unevenly, which puts pressure on its structure. When an area of glass becomes hot, expansion occurs. But cooler regions don't expand at the same rate.
So you can imagine that one part of the glass is expanding rapidly, while the other part is expanding slowly. In this case, stress will be created inside the glass. So it pulls on the glass and causes it to deform. If these stresses become too severe, the glass will break. In fact, the glass is broken only to reduce its own stress. But in our opinion, the glass is too fragile.
Thermal stress levels also depend on three factors:
1. The temperature difference between the hot part and the cold part of the glass: the greater the temperature difference, the greater the stress.
2. The speed of temperature change: Generally speaking, when the temperature rises or cools rapidly, the speed of glass expansion or contraction is faster. Which increases the stress.
3. The thickness and shape of the glass: thinner, more irregular glass is more likely to break. Because it can't withstand temperature fluctuations.
To minimize thermal stress, avoid exposing the glass to extreme or rapid temperature changes. For example, do not pour boiling water over cold glass and do not expose the glass to freezing temperatures. This rapid temperature change makes the glass more likely to break. Protecting glass from thermal stress is the key to preventing glass breakage. Therefore, we should pay attention to the temperature environment of the glass in our life.
Why does glass make a sound when it breaks?
Even if you haven't heard the sound of glass breaking in your life, you can hear it on TV. The sound of glass breaking is caused by sound waves vibrating the glass at its resonant frequency. When sound waves pass through the glass, they cause the glass molecules to vibrate. Each type of glass has a specific frequency range. To make its molecules vibrate the most, this is called its resonance band. If the sound waves match the resonant frequency, the vibrations build up and cause the glass to break.
Cracks usually start with small fragments or cracks on the edge or surface of the glass. As sound waves continue to vibrate the glass, these defects expand, cross and spread throughout the material. Once cracks connect and compromise the structural integrity of the glass. The whole glass will shatter. Acoustic cracks are more likely to occur in larger glass plates because larger glass plates have a larger surface area for cracks to occur.
To prevent acoustic breakage, choose a glass material whose resonance frequency is outside the normal ambient noise range. Things like laminated glass or tempered glass are good choices. They are more resistant to acoustic breakage. If you often hear specific noises that cause glass to break. The noise may continue to damage other glass in the area. The only way to stop the glass from breaking unpredictably is to eliminate the sound source. With proper precautions, glass can remain intact even when exposed to loud noises.
How can glass spontaneously break?
Sometimes without the influence of external factors, the glass will spontaneously break. There are several reasons for this.
Internal stress: In the glass manufacturing process, uneven cooling can create internal stress. At the same time, these stresses will remain in the glass. Over time, these stresses build up. Then it is possible to suddenly weaken the glass. The glass then breaks. This happens from time to time. Maybe the glass has been installed for a long time, and one morning it may suddenly break. Therefore, we should pay attention to reducing the internal stress of the glass when making glass. To prevent the occurrence of such accidents frequently.
Temperature change: Temperature change is a headache. Because other things maybe we can control, but we can't change the outside temperature. The sun may still be shining in the morning, and the sudden arrival of cold air may cause the glass to break. The temperature difference is enough to stress the glass. Glass with low coefficient of expansion is recommended. It is also best to reduce the use of glass in places with large temperature changes.
Edge damage or defects: If there is a gap, scratch or crack on the edge of the glass plate, it can become a stress concentration point. This makes it easier for the glass to break under temperature changes or impact. Don't underestimate the small invisible scratches. Sometimes these little cracks are the trigger for the glass to break. It might just spontaneously break one day. Be careful with scratches and try to protect the glass. Prevent glass edge damage. It is also recommended that you purchase glass from reputable suppliers. Can reduce the production of glass defects. Like us!
Chemical reactions: In rare cases, impurities or chemicals in glass can react with environmental factors such as temperature or UV exposure. Although this is unlikely, they can also weaken the properties of the glass. Eventually, the glass may spontaneously crack or break. Using a supplier that meets industry standards for glass composition and purity is also one of the best ways to avoid this problem.
A way to prevent glass from breaking
Although there are many possible reasons for glass breakage, there are some ways to reduce glass breakage.
Annealing: After the glass has been formed, it needs to undergo an annealing process and slowly cool to room temperature. This relieves the stress created inside the glass. So make sure the glass you buy is properly annealed.
Tempered: Tempered glass after rapid heating and cooling, the strength can be greatly improved. Glass forms a shell when it is compressed. When stretched, it forms an inner part. The two work together to control cracks. This is recommended for areas such as doors or tables.
Sandwich: Adding a sandwich to the glass is also a good way. We all know that the safety of laminated glass is also better. It can reduce the splash of glass fragments when broken. It greatly protects people's safety.
Proper installation: When installing the glass, make sure the weight is evenly distributed between the frame and the hardware. Make sure the glass is properly secured to prevent excessive movement or vibration. When you encounter heavy glass panels, determine multiple connection points to support the glass weight.
Conclusion
In general, the reason for the breakage of glass is still its fragility and irregular molecular structure. Once there is a crack in the glass, the whole structure will lose its stability and collapse. After reading the article, you should also understand the causes of glass breakage and prevention methods. And the appropriate glass material can be selected according to its intended use. If you are still not clear, you can contact us! We can provide professional advice.
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