What is the composition of glass?

Glass, also known as colored glaze in ancient China, is a transparent, high strength and hardness, airtight material. Glass is chemically inert in daily environment and will not interact with living things, so it is widely used. Glass is generally insoluble in acid (except that hydrofluoric acid reacts with glass to form SiF4, which causes glass to be corroded); But soluble in strong alkali, such as cesium hydroxide. Glass is an amorphous supercooled liquid. The molten glass cools rapidly, and each molecule forms glass because there is not enough time to form crystals. Composition Ordinary glass is mainly the chemical composition of amorphous supercooled liquid silica (SiO2 _ 2), that is, timely or sand with wollastonite and sodium carbonate as raw materials. The melting point of pure silica is 2000 degrees Celsius. Therefore, when making glass, two materials are usually added: sodium carbonate (Na2CO3) and potassium carbonate (K2CO3). In this way, the melting point of silicon dioxide will be reduced to about 1000 degrees. However, because sodium carbonate can make glass soluble in water, it is usually necessary to add appropriate amount of calcium oxide and CaO to make glass insoluble in water. Transparency to visible light is the biggest feature of glass. Ordinary glass is opaque to ultraviolet rays with wavelength less than 400 nm, because sodium carbonate is added in the manufacturing process. If ultraviolet rays are to penetrate, glass must be made of pure silicon dioxide. This kind of glass has high cost and is generally called timely glass. Pure glass is also transparent to infrared rays, and can make several kilometers of glass fibers for communication purposes. Other ingredients are usually added to ordinary glass. For example, lead glass, which looks dazzling, adds lead to the glass, which increases the refractive index of the glass and produces more dazzling refraction. As for Pyrex, boron is added to change the thermal and electrical properties of glass. Adding barium can also increase the refractive index. The glass for making optical lenses is made by adding thorium oxide to greatly increase the refractive index. If the glass is to absorb infrared rays, iron can be added. For example, there is this kind of insulating glass in the projector. Adding cerium to 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 glass. A little more manganese can make lavender glass. Selenium has a similar effect. A small amount of cobalt can make blue glass. Tin oxide and arsenic oxide can lead to opaque white glass. This kind of glass seems to be white ceramic. Copper oxide can cause turquoise glass. Copper can lead to dark red and opaque glass that looks like a ruby. Nickel can be made into blue, deep purple or even black glass. Titanium can cause a brown color. A small amount of gold (about 0.00 1%) makes the glass very bright, just like the color of ruby. Glass made of uranium (0. 1 to 2%) is firefly 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 complicated and has not been fully understood so far. Sometimes natural glass, called obsidian or volcanic glass, appears in volcanic lava. Obsidian can be used to make simple sharp knives. People in history believe that natural volcanic glass has been used since the Stone Age. Ancient Egypt recorded that glass was used as a utensil around 2000 BC. In 200 BC, Babylon invented the method of blowing glass to control glass, and then this method was introduced to Rome. In Europe, the Portland bottle in Rome around the first century A.D. was a glass relief work. 1 1 century, Germany invented the technology of making flat glass. Blow the glass into a ball and then make it into a cylinder. Cut the glass while it is hot, and then lay it flat. This technology was further improved in Venice in the13rd century. Venice is the center of European glass manufacturing industry in the14th century, and many tableware and utensils made of glass are made in Venice. In the future, many glass workers in Europe will learn from Venice. The glass bronzing machine invented in 1827 opened the way for mass production of cheap glassware. Sometimes acid or other corrosive materials are used to carve artistic patterns on glass. The traditional method is carved by craftsmen when blowing or casting glass. Later, in 1920, the method of adding sculpture to the mold and using different colors of glass was invented, so after 1930, mass-produced cheap glassware gradually appeared. China also began to make glass in the Western Zhou Dynasty. Glass tubes, glass beads and other objects have been found in the ancient tombs of the Western Zhou Dynasty. Before the Northern and Southern Dynasties, people in our country often called it glazed objects, which were made by fire and transparent in glass. The song dynasty began to call it glass. In the Ming and Qing dynasties, it was customary to call glass opaque ceramics fired at low temperature. Strictly speaking, many "colored glasses" at that time did not belong to modern "glass" Types of Glass Float Glass/Annealed Glass About 90% of the flat glass in the world is made of "float glass" invented by Sir Astor pilkington of pilkington Glass Company in 1960s and 1950s. This kind of glass is also called annealed glass. The method is to pour the glass solution into a tin-dissolving tank. After the glass floats on the tin surface, it naturally forms two smooth surfaces, which are slowly cooled and grow into strips to leave the tin bath. After fire polishing, it almost completely turned into flat glass. Generally, glass is produced according to the standard thickness, which is divided into 2, 3, 4, 5, 6, 8, 10, 12, 15, 19 and 22 mm Using ordinary annealed glass in buildings will cause potential danger, because when this kind of glass breaks, Building codes in most places prohibit the use of ordinary annealed glass where the glass may be broken. For example, this kind of glass is not allowed in bathrooms, glass doors, French windows, fire exits and so on. Before the invention of float glass, annealed glass was also produced by blowing and rolling. Unless mechanical polishing is carried out at high cost, it is difficult to manufacture flat glass by these methods. Tempered glass Tempered glass, quenched glass or tempered glass is made of annealed glass after heat treatment. The annealed glass is cut to the required size, the edges are polished or drilled, and then strengthened. Put the glass on the roller table, push it into an oven that exceeds the annealing temperature of 600 degrees Celsius, and then quickly cool it with air. The glass surface is cooled below the annealing temperature, and rapidly hardens and shrinks. While the inside of the glass still flows for a short time. When the inside of the glass shrinks, it will cause compressive stress on the surface and tensile stress inside the glass. Generally speaking, the strength of strengthened glass is four to six times that of annealed glass. The reason is that the fine cracks on the glass surface will be pressed tightly by stress, and the possibility of cracks in the inner layer is also low. But tempered glass also has disadvantages. Because the stress in the glass needs to be balanced, if there is any damage or crack in the strengthened glass, the whole glass will break into nail-sized pieces without sharp corners. Therefore, strengthened glass should be cut and polished in advance before strengthening treatment. Moreover, compared with annealed glass, strengthened glass has lower hardness and is easy to scratch. Reinforced glass has many uses in architecture, and many frameless components such as glass doors and glass curtain walls often use reinforced broken glass. The glass that needs to be installed will also use tempered glass. Tempered glass is broken, and the fragments formed are small and round, so there is less chance of injury. Therefore, it is regarded as one of the safety glasses. However, tempered glass may burst suddenly when it is hit, so tempered glass is not suitable for some occasions. Tempered glass was discovered hundreds of years ago, but its principle was not known at that time. /kloc-In the 7th century, Prince Rupert of England dropped molten glass into water to make glass beads. This teardrop-shaped glass is so hard that it won't break even if you hit it with a mallet. But as long as the tail of the glass falls off, it will suddenly explode into powder. This kind of thing has also been brought to court to tease people, and it is called "Rupert's drop". Laminated glass Laminated glass was invented by French chemist Edward Benediktus in 1903. When he did the experiment, he did not intend to put a layer of nitrocellulose in the glass bottle. Later, he found that the glass bottle fell to the ground and cracked. He wants to apply the glass with plastic interlayer to the windshield of the car to reduce the casualties caused by the car accident. At first, automobile manufacturers were not interested in his invention, but the gas mask produced in World War I was the first to use this invention. It was not until 1936 that the use of polyvinyl butyral (PVB) as interlayer was improved, and laminated glass began to be popularized in automobiles, and later became a mandatory safety standard of the government. Modern laminated glass is composed of two or more layers of ordinary annealed glass, and most of the interlayer in the middle is PVB. Put PVB between two layers of glass, heat it to about 70 degrees Celsius, then press out the air in the middle with a roller, and let PVB stick the two layers of glass tightly together. General laminated glass is composed of two layers of 3 mm glass with a 0.38 mm interlayer between them. The total thickness is 6.38 mm, and more layers and thicker glass can be used to increase the strength. For example, bulletproof glass is made of multiple layers of thick glass, and the total thickness can reach 50 mm When the glass on the laminated glass is broken, the laminated glass will still stick the two layers of glass together to prevent the whole glass from breaking into pieces and hurting people. Laminated glass is also called safety glass. The PVB layer in the middle of the laminated glass also increases the sound insulation effect of the glass, which can block more than 99% ultraviolet rays. The windshield of a car is laminated glass. But most of the other glass in the car, such as side glass and back glass, are tempered glass. If you pay attention, you will find that the windshield of a car will crack only after a collision. Other glass will break into small particles. Dimming glass Dimming glass is also called gathering privacy glass, also called electrically controlled liquid crystal glass, electrically controlled dimming glass or PDLC glass, also called magic glass or color-changing glass. When the power supply of the electronic control product is turned off, the liquid crystal molecules in the dimming will be irregularly scattered, so that the light cannot enter, and the dimming glass will have an opaque milky appearance; After electrifying, the liquid crystal molecules inside are arranged neatly and light can penetrate freely. At this time, the electrically controlled liquid crystal glass is transparent. Dimming glass was first invented by Kent State University and commercialized by American Polytronix, Inc. on 1990. It has a history of more than 20 years. Because of the high manufacturing cost, it is mostly used in high-end hotels, villas, various high-end commercial places and various privacy protection fields. Because the brand name of electronically controlled dimming glass under Polytornix, Inc is Polyvision Privacy Glass, [Polyvision] is also regarded as synonymous with dimming glass in the industry. Self-cleaning glass This is a new technology glass invented by pilkington Company, which is mainly used in buildings and automobiles. The outer surface of the glass is coated with titanium oxide with a thickness of about 50 nanometers, which will catalyze the decomposition of organic matter on the glass under ultraviolet irradiation. In addition, the hydrophilicity of the glass surface helps to form a water film on the glass when it rains, which can wash away the decomposed organic matter without leaving water traces and achieve the effect of self-cleaning. LED glass LED glass is a high-tech photoelectric glass product made by Taiwan Province Baochuang Technology Co., Ltd., which is a patented product that embeds LED light source into glass to form various styles and patterns. Designers can use the bright characteristics of LED glass to develop outstanding display products, and LED itself has excellent brightness and energy-saving characteristics. LED glass technology can make the glass surface invisible, which is suitable for all kinds of flat and curved glass and meets various design and application requirements. Laser glass Laser glass, also known as holographic glass or laser glass, is a patented technology product that combines laser holographic patterns with glass. Laser glass can make graphics have the characteristics of endless color changes, three-dimensional images and eye-catching, and can be widely used in various fields such as home design, home and business place decoration or home appliance panel decoration. Luminous glass Luminous glass can emit unique fluorescent effect at night, which makes the place where luminous glass is applied full of romantic atmosphere. Luminous glass can guide the direction and also serve as a light source at night. This is a brand-new attempt to apply luminous technology in the field of glass, and this innovative product will lead the glass manufacturing technology into a new era. Mainly used in commercial places and home interior design, decoration, doors and windows, product display cabinets, furniture and other fields. This technology was invented by Taiwan Province Baochuang Technology Co., Ltd. ..