Glass
close Ordinary glass is mainly composed of silicon dioxide (SiO2, the main component of quartz and sand). The melting point of pure silica is 2000 degrees Celsius, so sodium carbonate (Na2CO3, that is, soda) and potassium carbonate (Potash, K2CO3, potash) are generally added when making glass, so the melting point of silica will drop to about 1000 degrees Celsius. However, sodium carbonate will make the glass soluble in water, so an appropriate amount of calcium oxide (CaO) is usually added to make the glass insoluble in water. Transparent to visible light is the biggest feature of glass. General glass is not transparent to ultraviolet light with wavelength shorter than 400nm because sodium carbonate is added during manufacturing. If the ultraviolet ray is to penetrate, the glass must be made of pure silicon dioxide. This kind of glass has a high cost and is generally called quartz glass. Pure glass is also transparent to infrared rays, and can be made into several kilometers of glass fiber for communication purposes. Other ingredients are usually added to common glass. For example, the crystal glass (Lead glass, also known as lead glass) that looks very shiny and dazzling adds lead in the glass, which increases the refractive index of the glass and produces more dazzling refraction. As for Pyrex glass, boron is added to change the thermal and electrical properties of the glass. Adding barium can also increase the refractive index. Glass used to make optical lenses is made by adding thorium oxide to greatly increase the refractive index. If you want glass to absorb infrared rays, you can add iron, and the projector will have this kind of heat-insulating glass. Cerium in glass will absorb ultraviolet rays. Adding various metals and metal oxides to glass can also change the color of glass. For example, a small amount of manganese can change the light green color caused by iron in the glass, and a little more manganese can cause the light purple glass. Selenium has a similar effect. A small amount of cobalt can make blue glass. Tin oxide and arsenic oxide can make opaque white glass, which looks like white ceramics. The oxide of copper will make the green glass. Metal copper will create dark red, opaque glass that looks like ruby. Nickel can make blue, dark purple, or even black glass. Titanium can cause brownish yellow. A trace of gold (about 0.001%) causes the glass to be very bright, like the color of ruby. The glass caused by uranium (0.1% to 2%) is fluorescein yellow or green. Silver compounds can make orange to yellow glass. Changing the temperature of glass will also change the color caused by these compounds, but the chemical principle is quite complex and has not been fully understood yet. In the next five years, China will embark on a dual transformation of economy and society, with the transformation of development mode and adjustment of economic structure as the main line, and deploy three major transformations of China's economy and society from external demand to domestic demand, from high carbon to low carbon, and from a strong country to rich people. The key objectives of China Glass during the "12th Five Year Plan" period are: to adjust the industrial structure by focusing on energy conservation and emission reduction; We will speed up resource integration with large enterprises as the leading force. It is hoped that China's glass industry will transform from large to strong in the next decade.