Quartz is a very special material, mainly used in industry and scientific research. Has the properties that other materials do not have, and is applied in many high-tech fields. Long experience and continuous research and development, so that the new century quartz can be stable production of this material, innovative production technology, so that the characteristics of quartz in the application to play out. Share these knowledge and experience, so that our customers to better understand the processing of quartz and quartz itself.
Characteristic
Artificial glass has been available for 3500 years, quartz sand and sodium containing ash and chalk mixture, the mixture is heated to 800-1000 degrees to form a glass, glass and metal oxide mixed different form different colors, this glass pearl high education glasses and flask with glass melting mixture of glass about 600 low degrees.。Quartz glass is a purified form of glass, which is composed of only two elements --- silicon and oxygen, due to his high purity and microstructure, resulting in a series of characteristics.thermal stabilitylow thermal expansionHigh homogeneityLow thermal conductivityExcellent thermal shock resistanceHigh optical transmittance in infrared and ultravioletHigh chemical resistanceLow dielectric lossDue to so many characteristics, quartz glass is an important material in the laboratory and industrial field.The new century quartz not only provide through a variety of all kinds of production process of transparent quartz glass, and opaque quartz glass. By increasing the content of bubbles become transparent quartz glass opal quartz glass bubble size and shape determines the reflection characteristics of opal quartz tube.
Production method of quartz
Due to the different raw materials, quartz can be divided into two different groups if the use of natural quartz as raw material, called fused silica. If usedFour chlorinated silicon as the raw material is called fused silica, the production method depends on the raw material, can be divided into the following methods:Electric melting methodGas refining processSynthesis methodElectric melting methodElectric melting is the most common method of melting quartz sand production. The two methods can be divided into: arc melting and resistance melting furnace.Arc melting: voltage between two electrodes. When the voltage and current are sufficiently high, the air between the electrodes is discharged. Electronic discharge is also known as the plasma, can provide thousands of degrees of temperature, arc in the surface of what the surface of the surface of the quartz sand melting into the glass state.The purity and size distribution depends on the quartz glass, can be white, transparent or translucent glass objects often used in arc melting rotational symmetry of the resistance heating process can be divided into continuous and discontinuous process.In a continuous process, quartz sand is poured from the top of the furnace, and the furnace is composed of an electric heating component wrapped around a metal crucible.The crucible is at normal atmospheric pressure or below atmospheric pressure to prevent the oxidation of refractory metals. Irregular structure glass mesh in microcrystal structure 1800 degree rule, the molten material after forming holes in the bottom of the crucible, rod segment or other products of various specificationsThe discontinuous melting method, a large number of raw materials placed in the vacuum furnace, surrounded by refractory materials, this method is used to produce large monomer material.Gas refining processJNC quartz crystal with hydrogen and oxygen. The basic concept of this process is composed of quartz sand into the high temperature flame. The crystal particles in the flame are melted and fused together to form quartz glass, which is different from the flame. A method of fused quartz droplets attached to the quartz rod, remove quartz rod, a circular mound. Another way to collect the fused silica in a bowl, and then through the hole in the bottom of the bowl, hot drawn shape you want the glass, such as weight bucket box. According to different parameters, also can produce transparent and opaque weight.
structure
At first glance, because the quartz glass is composed of a single oxide, so the structure and chemical properties of quartz glass is relatively simple, the surface of the crust containing silica silica ore, but only a few content of more than 99.98% for the atomic structure of quartz glass raw materials as general as tetrahedral structure, silicon atom is located in the center, four oxygen atoms are arranged in a ring all around. These tetrahedral angles are connected with each other to form a three-dimensional structure. But they are arranged inside the quartz crystal, arranged in a ring, and in the glass, the network structure is made up of irregular twisted rings.The increase in the temperature of each material will lead to an increase in the atomic motion, which requires a larger space. In this kind of vibration, the inverse of the two mesh is different. At a certain temperature, the regular grid is arranged again, and the irregular grid can attract the atoms that vibrate. Because the grid can not be completely filled, so the quartz glass has a very low thermal expansion.The irregular structure is the typical structure of any glass, which makes the quartz glass not only resistant to high temperature, but also can adapt to the sudden change of temperature. In addition, there is a good plasticityTaking into account that not too cold liquid, at least from the thermal balance of this point, the quartz should be crystalline solid, rather than liquid. This fact is the key to understanding why the quartz is lost. Although the thermal dynamics on the preferred quartz glass is crystal, high viscosity prevents the necessary structural reconstruction. In other words, rapid cooling, the molecules can not be quickly re arranged, so that is conducive to the production and processing of quartz, but in a certain environment, the removal of coercive force, resulting in the recovery of glass to the crystal. Usually occurs when the temperature is elevated and there is impurity, the silicon oxygen bond is broken. Alkali metals (e.g., sodium and potassium) are the most common pollutants, which make the.In 275 degree and contraction, when the crystal structure suffered phase change, the loss of the phenomenon can occur.
chemical properties
Fused silica can withstand most liquids (metals, solutions, and acids). Hydrofluoric acid and phosphoric acid corrosion of fused quartz. Quartz glass and alkali metal and alkaline earth metal reaction, because in the heating stage, alkali metal and soil metal can promote devitrificationQuartz glass is made up of very pure silica. The other elements of the chain become impurities. Although the percentage of these impurities is very low, these impurities have an important influence on the quartz glass. Purity is determined by the materials used. The production of pollutants mainly comes from the mode of production. Every stage of the production process should be in the prevention of pollution, so as to ensure the purity.The most common impurities are metal, such as aluminum, iron and other, water, chlorine, these impurities are mainly in the glass grid, and the impact of the viscous absorption of electrical properties. They also affect the characteristics of raw materials.The purity of fused silica and fused quartz is very high, and the metal content of synthetic quartz is less than 1ppm. Fused silica impurities close to 20ppm, the main pollutant composition of AL2O3, a small portion of alkali metals, TiO2 mGo ZrO2 Fe2O3Metal impurities mainly come from natural quartz, very careful control of the processing process, you can greatly reduce the impurity content, from 200ppm to 20ppmAluminum is the most impurity, replacing silicon atoms, in the presence of quartz glass. At high temperatures, he has a very low activity, resulting in any production stage is not possible to remove.
hydroxyl
In addition to the metal impurities, fused silica and fused quartz also contains some water hydroxyl groups, the hydroxyl group into the quartz crystal lattice will reduce the viscosity of quartz, so the price of low temperature resistance of quartz. Other physical properties will be affected, such as light transmittance, infrared absorption band formed in each process has its typical hydroxyl content of fused hydroxyl value 1-30ppm for the lowest Ronghu under vacuum or melt in negative pressure conditions. During annealing, the humidity can also affect the hydroxyl content of air silica contains many hydroxyl groups, because of air silica using oxyhydrogen melting synthetic quartz by flame hydrolysis chemical hydroxyl content greater than 1000ppm reduced synthesis of silica hydroxyl by high temperature chlorination.
physical characteristics
Due to the high purity and microstructure, the use of glass has more properties. Thermal conductivity of quartz glass is low, low thermal expansion coefficient, high impact resistance, insulation In addition, low heat conductivity. Quartz glass has a high tensile strength in practice, depending on the surface condition of the glass. In the tensile force, small defects such as scratches will cause the rupture of glass grid structure, will lead to broken fused quartz and fused quartz glass is not a good insulator conduction electron conducting ion. All the external ions of the glass grid contribute to the electrical conductivity, the electrical sensation of ions, and the temperature of charge and electron. With the increase of temperature, the resistance of quartz glass decreases, and the activity of the electron increases. The lower the impurity content, the smaller the conductivity of quartz. Quartz glass can be through a lot of band light, from 0.18 micron to 3.5 microns, the number of absorption at 2.73 microns depends on the size of the OH. The appearance of infrared peaks due to the lattice vibration and the thickness of the glass. The position of the ultraviolet absorption peak depends on the chemical element in the glass grid.