Do you believe that there is a particularly unbreakable object, and at the same time it is so fragile that it is particularly prone to breakage? Moreover, this paradox is nothing more than a piece of glass, a piece of glass called “Rupert’s Tears” (also known as Dutch Tears).
Fragile glass bulbs
Small choreography is not believed anyway, what can be easily broken, and not easy to break? What’s more, it’s just a piece of fragile glass.
What is glass? What is glass?
We know that solids can generally be divided into crystals and non-crystals. Crystals are solids in which particles are periodically arranged in microstructures, in other words, a minimum period that recurs multiple times in one direction. And include sesame, diamonds and salt, which are large monocrystals, while most metals, ceramics, etc. are polycrystalline (polycrystalline is a crystalline material consisting of more than two single crystals).
Beautiful diamond is a single crystal
The main feature of non-crystalist is the long-range ordering characteristic of no crystal, and the binding between internal particles is irregular. Glass is one of the most common noncrystals. Broadly speaking, “glass” consists of aglass-state transformation processes that have an amorphous structure on an atomic scale and are presented when heating to liquid.
Glass varies greatly in its chemical composition due to different types, but can generally be divided into silicon dioxide glass and special glass. Most of them fall into the former category. The glass is mainly made of sand (the main component silica), limestone (the main component of calcium carbonate) and sodium carbonate. Although molten silica itself is an excellent glass, the melting point of silica is more than 1700 degrees Celsius, and the energy required to reach such a high melting point is very high, which makes the glass very expensive (such as some fused quartz optical lenses, which are much more expensive than ordinary glass).
Glass bottle production line
So in the production of ordinary glass to add sodium carbonate as a melting agent is to reduce the melting point of silica, by adding about 25% of sodium oxide to silicon dioxide, the melting point of silica can be reduced from more than 1700 degrees Celsius to 850 degrees Celsius, but this glass is easily soluble in water (this solution is called water glass). So add calcium oxide to make the glass not soluble. 
This could be a glass ball production process.
The reagents that color the glass are usually metal oxides. The same oxides produce different colors in different glass mixtures, and different oxides of the same metal can produce different colors. For example, cobalt blue-purple, chrome green or yellow, ferrooxide based on the glass mixed with it produces olive green or light blue. Adding finely chopped charcoal to the glass produces yellow. The palladium seems to be pale pink. Copper produces peacock blue, which turns green if the proportion of copper oxide is increased.
What’s so special about Rupert’s tears?
The Honour of Rupert’s Tears
So what’s so special about this ripple-shaped glass? (It feels like a pendant?) )
The head is very hard and the tail is very fragile. When cutting off its tail, due to the inability of internal tension to maintain an explosive break, Rupert’s tears break down explosively into powder when the tail is cut off. The second characteristic is that the head has an abnormal strength, if the pressure on its head alone, can withstand 15,000 Newtons of force. This is actually due to the presence of large residual stresses near the outer surface of the head, which can be measured by the use of the properties of double refraction induced by glass stress. Even if a bullet hits it won’t break.
Rupert’s tears from the bullet
Later, the researchers suspended the Dutch tears in a transparent liquid and lit the droplets with a red LED lamp. The researchers used polarizers to measure the optical delay of light passing through the glass, and then used the data to analyze the stress distribution throughout Rupert’s tears. The results showed that the droplet’s head had a much higher surface compression stress than previously thought, up to 700 mPa, nearly 7,000 times the atmospheric pressure. The surface compression layer is also thin, about 10% of the diameter of the droplet head.
Source: H. Aben; Appl. Phys. Lett. 109, 231903 (2016)
But the principle is simple. When the molten glass touches the water, the outer layer cools quickly while the inner layer remains molten. The effect of thermal expansion causes the liquid to expand as it becomes hot and contracts when it cools. This means that the molten glass inside is trying to expand as the cold outer layer shrinks inward. When the entire process is complete, these equal push pulls accumulate in a long chain that extends from the droplet’s head to the tail. Once the droplets are cooled, they are locked in this high tension state. Some would liken it to an arch: it’s incredibly strong, but if any part of it is damaged, the whole of Rupert’s tears will break. But it needs to be seen on a high-speed camera.
The cut-off tail is broken.
Although it has a feature that seems unlikely to appear on an object, Rupert’s tears are surprisingly simple. Is the melting glass dripping into the cold water produced by the glass beads, the glass beads will appear in the shape of a slug, the tail slender form.
Making Rupert’s Tears Source: YouTube
Why is it named “Rupert”? Prince Rupert, the nephew of King Charles I, is said to have first brought the strange glass to England in 1660. The little thing was also brought to the court to tease people, so it was called Rupert’s Tears. But according to reliable reports, the glass dates back to 1625, when it was made in Mecklenburg in northern Germany. However, it is also said that they were invented in the Netherlands, so it is also called Dutch Tears.
What’s the use of this thing?
In fact, the Dutch tears were made using quenching methods. The quenching method of producing tempered glass may have been inspired by Rupert’s tears.
In fact, there is also this kind of Tears of Rupert, at least since the 19th century, people know that certain conditions in a certain condition in the lava to produce similar to the Dutch tears of rock. Researchers at the University of Iceland and elsewhere studied glass particles from the explosive fragmentation of Dutch tears in the laboratory to better understand the process of thermal stress-driven magma fragmentation and ash ash formation in active volcanoes.
Similar structures of lava formation
Didn’t expect a piece of glass can also be fragile and solid contradiction unity, you also know what such a thing? You can share it in the message area and everyone.