Rupert's Tears Is this substance really flashy? According to its principle of formation and breaking, what are its applications in real life? How hard can something made from ordinary glass be? Maybe even the bullet can't penetrate it, can you believe it?
This kind of glass appeared in the 17th century. In the Batavian Kingdom at that time, a prince Rupert made this water drop-shaped glass and presented several such glasses to the King of England. This seemingly ordinary gift actually aroused great interest from the king, because even if the strong man, holding a hammer and smashing the head of the glass with force, it would not break. But just use your hand to gently pinch its tail and it will break instantly. People named this magical glass "Tears of Rupert" by the prince.
Why is Rupert's tears so tough that he can't even penetrate the bullet? It turns out that to make a Rupert Tears, you must first heat the melted glass at high temperature, and then let the glass fall into the ice water by itself by gravity. The glass quickly solidifies in ice water, and the shape of the teardrops is fixed. The moment it drips into the water, the surface of the glass solidifies when cooled, and molten liquid is wrapped inside. When these liquids solidify, due to thermal expansion and contraction and volume shrinkage, the glass shell is "pulled" inward, so that the glass shell is compressed inward. . At the same time, the outer layer of glass that has solidified will also apply a "tentic stress" to the inner layer of glass. These two forces fight against each other, forming a delicate state of equilibrium.
Ordinary glass can also become as hard as Rupert's Tears after high temperature heating and extreme cooling. What does this remind you of? That's right, the tempered glass on buses and high-rise buildings is made using this principle. Due to strong stress, tempered glass will not easily break. Even if it is destroyed under huge force, it will instantly break into small particles, and will not break into small pieces with edges like ordinary glass, which will not easily hurt people.
In order to reduce the impact of self-destruction, some manufacturers will glue the two layers of tempered glass with PVB. And sticking the multi-layer tempered glass together with strong glue makes bulletproof glass with greater strength.
