Knowledge of quartz glass products

Quartz is a very special material, mainly used in industry and research. Features that are not available in other materials are used in many high-tech fields. With long experience and continuous development, new century quartz can steadily produce this material, innovate production technology, and make quartz's characteristics play out in the application. Share this knowledge and experience to make our customers better understand quartz processing and quartz itself.

characteristic

Artificial glass has been available for 3500 years, quartz sand mixed with plant ash and chalky substance containing sodium, mixture formed glass heated to 800-800 degrees, glass with different metal oxide mixed to form different color, this kind of glass bead light wine glasses and a flask of higher education, with mixture of glass as a raw material of low melting point glass is about 600 degrees.

The quartz glass is a purified form of glass, consisting of only two elements - silicon and oxygen - resulting in a series of properties due to his high purity and microstructure.

Thermal stability

Thermal expansion

High homogeneity

Low thermal conductivity

Excellent thermal shock

The high light is studied through infrared and ultraviolet bands

High chemical resistance

Low dielectric loss

Because of so many features, quartz glass is an important valuable material in the laboratory and industrial fields

New century quartz not only provides various kinds of transparent quartz glass through various processes, but also provides milky silica glass. The reflection features of the milky quartz tube were determined by adding the bubble transparent quartz glass into the milky quartz glass bubble size and shape.

The method of production of quartz

Since the original material is different, quartz can be divided into two different groups. If natural quartz is used as the raw material, it is called fused quartz. If the

Silicon tetrachloride as the raw material is called fused quartz, and the production method depends on the raw materials, which can be divided into the following methods:

Fused method

Gas refining method

synthesis

Fused method

Electrofusion is the most common melting method of the melting quartz sand, and 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 high enough, air discharge between the electrodes. The electron discharge is also called plasma, which can provide thousands of degrees of temperature, the arc is moving on the surface of the surface, the surface of the quartz sand melts into the glass state.

Depends on the purity quartz particle size and distribution, the glass can be a milky white, transparent or translucent arc melting often applied in the rotational symmetry of glass objects, can be subdivided into continuous ohmic heating process and continuous process.

Continuous method, the quartz sand is poured from the top of the furnace, and the furnace is composed of electrically heated components wrapped around metal crucibles

The crucible is at normal atmospheric pressure or below atmospheric pressure to prevent refractory metal oxidation. In 1800 the microcrystalline structure of the rule becomes the irregular glassy reticular structure, and the molten material passes through the forming hole at the bottom of the crucible, producing the rod tube or other products of various specifications

Discontinuous melting method, a large amount of raw material is placed in a vacuum furnace, four weekly report of refractory material, this method is used to produce large monomer materials.

Gas refining method

JNC quartz melts a colorless crystal with hydrogen and oxygen. The basic concept of this process is composed of quartz sand entering the high temperature flame. The crystalline particles in the flame are fused together to form a quartz glass. There are different ways to remove the flame from the flame. A method to attach the fused quartz drops to a quartz rod, remove the quartz rod, and get a lead. Another method is to collect the fused quartz in a bowl and then, through the hole at the bottom of the bowl, draw the glass of the shape you want, such as the bucket of the drum. According to different parameters, it can also produce transparent and milky lead.

structure

At first glance, because quartz glass is composed of a single oxide, so the structure and chemical properties of quartz glass is simpler, the earth's crust on the surface of the silica containing silicon oxide ore, but only a tiny part content is more than 99.98% for quartz glass raw material is generally the atomic structure of tetrahedron structure, silicon atoms is located in the center, around the ring are arranged in four oxygen atoms. These tetrahedral angles are connected to each other to form a three-dimensional structure. But these tetrahedra, inside the quartz crystal, are arranged in an orderly circle, inside the glass, and these mesh structures are made up of irregular twisted rings.

The increase in temperature of each material will result in an increase in atomic activity, which will require more space. In this vibration, the reaction of the two grids is different. At a certain temperature, the grid of the rules is rearranged, and irregular grids can attract atoms that vibrate. Because the grid cannot be fully filled, the quartz glass has a very low thermal expansion.

Irregular structure is the typical structure of any glass, irregular structure makes quartz glass not only endure high temperature, but also can adapt to the abrupt change of temperature. There's also a good plasticity

Given that it's not a cold liquid, at least from thermodynamic equilibrium, quartz should be crystalline solid, not liquid. This fact is the key to understanding why quartz is lost. While the preferred quartz glass for thermal dynamics is crystal, the high viscosity prevents the necessary structural reconstruction. In other words, the rapid cooling of the molecules can not be rearranged quickly, which can help quartz production and processing, but in some circumstances, the removal of coercive force causes the glass to return to crystalline state. Normally, the silicon oxygen bond ruptures as a nucleation source under the conditions of heating and impurity. Alkaline metals (e.g., sodium and potassium) are the most common pollutants that cause quartz to fail.

In 275 degrees and contraction, when the crystalline structure suffers phase change, the phenomenon can occur.

The chemical characteristics of

Fused quartz can withstand most liquids (metals, solutions and acids). Hydrofluoric acid and phosphoric acid can corrode fused quartz. Quartz glass can react with alkali metals and alkaline earth metals, because in the heating phase, alkali metals and intermetallic metals can promote loss of penetration

The quartz glass is made of very pure silica. The other elements on this chain become impurities. Although the percentage of these impurities is very low, these impurities have an important effect on quartz glass. Purity is determined by the material used. The production of pollutants mainly comes from the process of production. Pollution should be prevented at every stage of the production process to ensure purity.

The most common impurities are metals, such as aluminium sodium iron and others, water and chlorine, which are mainly in the glass mesh and affect the viscous spectral absorption characteristics. They also influence the characteristics of raw materials.

Fused quartz and fused quartz are very high in purity, and the metal content of synthetic quartz is less than 1ppm. The fused silica impurities are close to 20 parts per million, and the main pollutants consist of AL2O3, a small amount of alkali metal, and Fe2O3 TiO2 mGo ZrO2

The metal impurities are mainly from natural quartz, and very careful control process can greatly reduce impurities, from 200 PPM to 20 PPM

Aluminum is the most impurities, replacing silicon atoms and being in quartz glass. Under high temperature conditions, he has very low activity, which can not be removed during any production stage.

The hydroxyl

The hydroxyl content

In addition to metal impurities, fused quartz and fused quartz also contain a number of hydroxyl groups, which can reduce the viscosity of quartz in the quartz grid and therefore have a low temperature of quartz. Other physical characteristics will be affected, as the light transmittance, infrared absorption band formed each process has its typical hydroxyl content fused hydroxyl value minimum 1-30 PPM because banyan under vacuum conditions or under the condition of negative pressure melting. Annealing, humidity can also affect the hydroxyl content in gas refining quartz contains a lot of hydroxyl groups, because gas refining quartz using oxyhydrogen flame melt synthetic quartz by flame hydrolysis chemicals hydroxyl content is greater than 1000 PPM can reduce synthetic quartz hydroxyl through high temperature chlorination.

Physical properties

Glass has more properties because of its high purity and microstructure. Quartz glass has low thermal conductivity, low expansion coefficient, high thermal impact, insulation. There is also a low thermal conductivity. Quartz glass has high tensile strength and depends on the surface condition of the glass in practice. Under the action of tensile force, small defects such as scratches can lead to broken glass grid structure, then lead to the glass broken fused quartz and fused silica are good insulators can't conduction electrons can conduct ions. All of the external ions in the glass grid are conductive to electrical conduction, and the ion's bombardment has been associated with charge and electronic temperature. As the temperature increases the resistance of quartz glass decreases and the activity of the electron increases. The lower the impurity content, the less the conductivity of quartz. Quartz glass has light from many wavelengths, from 0.18 micron to 3.5 microns, and how much depends on the size of the OH value at 2.73 microns. The emergence of infrared peak, due to lattice vibration and glass thickness. The location of the uv absorption peak depends on the chemical element in the glass grid.