What Is Glass ?
Glass is our common building material. Generally,float glass is used for ordinary window glass. The main raw materials of float glass are soda ash, limestone and quartz sand, which are obtained by melting together sodium silicate, calcium silicate and silicon dioxide. When people produce ordinary glass, the raw materials are pulverized, mixed in an appropriate ratio, and then placed in a glass kiln to strengthen the heat. After the raw materials are melted, relatively complicated physical and chemical changes occur.
Glass does not have a certain melting point, but is gradually softened in a certain temperature range. In the state where the glass is softened, it can be made into an article of any shape, and the commonly used glass bottles and glasses are made of ordinary glass.
By adding different substances to the glass production process and adjusting the chemical composition, it is possible to produce glass with different properties and uses. For example, the addition of boron oxide in the production of ordinary glass can improve the chemical stability of the glass and lower the coefficient of thermal expansion, thereby making it more resistant to high temperatures and chemical corrosion, and can be used to manufacture advanced chemical reaction vessels. In addition, the optical glass produced by adding lead oxide has a high refractive index and can be used for manufacturing ophthalmic lenses as well as lenses for cameras, telescopes, and microscopes. Also, if some metal oxide is added to the production of glass, it can be made into colored glass. When cobalt oxide is added, the glass will appear blue; when cuprous oxide is added, the glass will appear red. Generally, the ordinary glass we see is light green because the raw material is mixed with ferrous iron.
In addition, the glass can be processed in various processes. For example, ordinary glass is turned into a tempering furnace for heating, and when it is close to the softening temperature, it is quickly taken out from the furnace, and then blown with cold air to obtain tempered glass. The mechanical strength of tempered glass is 4-6 times larger than that of ordinary glass, which is resistant to cracking and is not easily broken. After the tempered glass is broken, the pieces have no sharp edges and are not easy to injure people. In addition to tempered glass, there are many special glass materials that play an important role in our lives.
