Glass is one of the most ancient materials, which is widely used in all spheres of human practical activity due to a set of useful qualities and properties. During its existence (and this is more than 5 thousand years), its chemical formula has remained almost the same, only its qualities have changed.
Quartz glass
Over the years, man has sought to create glass more and more transparent and resistant to various destructive factors. As a result of such targeted improvement, quartz glasses appeared - a completely new type of material with astonishing characteristics. Perhaps this glass will determine the direction of further development of mankind.
Quartz glass is a product of the melting of pure silicon oxide (SiO
2 ). Unlike ordinary glass, this material is in an amorphous state, that is, it does not have an exact melting point and gradually changes from solid to liquid upon heating. Largely due to this property, quartz or silicate glass has found such wide application in industry.
Quartz glass structure
The amorphous nature of the material is explained by its structure, which is based on silicon-oxygen tetrahedra. SiO 2 molecules “bind” to each other due to the mutual attraction of oxygen atoms.
Together they form three-dimensional grids, despite the fact that there is no strict order in the arrangement of molecules relative to each other. That is why quartz glasses have the properties of amorphous materials.
Silicate glass, as usual, is obtained by melting the feedstock. As such, pure silica can be used - rock crystal, vein quartz, quartz sand, as well as silicon oxide obtained by artificial means.
Differences between quartz glass and ordinary
Depending on the type of raw material chosen, certain properties of the final product are also determined. So, to obtain a crystal clear and transparent material, rock crystal is used.
The main difference between silicate glass and ordinary glass is a high melting point - more than 1500 ° C. In this case, silicon oxide begins to emit intense light radiation in the visible spectrum, that is, it begins to glow.
Due to the amorphous structure of the feed, the melting process can take a considerable time. The molten composition is highly viscous, which does not allow it to stack or move. This makes it difficult to produce quartz glass with the same wall thickness.
Production Features
In view of all these features, the production of silicate glass is possible only on specialized equipment. In smelters, a high temperature must be maintained, and in order to create glass products, it is necessary to maintain an open flame jet with a temperature of 1800 ° C or higher.
There are special requirements for the production room - it must be sterile. A small amount of foreign particles will inevitably lead to the fact that the finished quartz glass will soon crack and lose their properties.
Special qualities should be possessed by production workers - glassblowers. They have to deal with extremely high temperatures - one mistake during operation can lead to serious injuries, burns.
All the main glass blowing tools are made of heat-resistant materials - granite, tungsten, which, among other things, are very heavy. Therefore, employees must be physically strong and resilient.
Properties of quartz glass
Silicate glass has low electrical conductivity, which is why it is often used as a dielectric in complex electrical appliances. The main useful properties that quartz glasses have can be divided into three groups:
- Thermal. Resistance to high temperatures (1200 C about ), high coefficient of thermal expansion (15 times higher than that of ordinary glass), which determines the resistance to sharp and significant temperature fluctuations (in production the products are cooled with a stream of ice water).
- Chemical. Glass is chemically neutral, does not react with all alkalis and acids, except phosphoric and hydrofluoric acid (the reaction begins at a temperature above 300 ° C).
- Optical The refractive index of quartz glass is 150 times lower than that of ordinary (n e = 1.46). Due to this, it impeccably transmits not only sunlight and ordinary light, but also does not trap either infrared or ultraviolet radiation.
All these properties make it possible to use quartz glass as a building material, as well as for the production of laboratory glassware, optical instruments, electrical equipment, and heat-resistant refractory materials. One of the main areas of its application is the manufacture of optical fibers.
Optical quartz glass
Depending on the technology used in the production, quartz glass may be opaque and transparent. In the first case, a large number of gas bubbles will be present in its structure, which intensively scatter light.
Transparent glass, or optical quartz glass, as it is also called, is absolutely homogeneous, does not contain bubbles. Due to this feature, the material is used in the manufacture of
optical cables for high-speed data transmission, optical lenses and prisms.
Brands and Series of Optical Glass
There are several brands of optical glass: KU-1, KI, and KV. Products differ in their ability to transmit visible, ultraviolet and infrared radiation. The most transparent is KI glass - it is capable of transmitting light at a wavelength of 2600-2800 nm, the least transparent is KV.
Depending on the raw materials used, optical quartz optical glass may have different light transmittance. GOST 15130-86 contains information on three series:
- 0 - material used under normal operating conditions;
- 100 - glass, resistant to ionizing radiation of insignificant strength;
- 200 - raw materials that can be used in conditions of intense ionizing radiation.
The brand and series of glass form the product code. It is applied at the factory and determines the specific type of glass. In our country there is no unified encryption system, therefore, each enterprise designates its products according to its own understanding.
Application area
Silicate glass is used to make a wide variety of products. In scientific and industrial laboratories, quartz glass tubes are in demand, which are used for measuring the liquid level, manufacturing electric heaters, conducting chemical reactions and storing aggressive substances.
Opaque glass has also been widely used in production. It is used where it is necessary to control liquid products at high temperatures and, due to its low cost, is used everywhere.
Optical glass is used in shipbuilding and rocket science, mainly for the production of lighting devices. In petrochemical plants, this material is valued for its high resistance to chemicals and is used to control aggressive liquids. In airplanes, cabins glaze over them and are also used as thermal insulation.
Manufacturers make products in accordance with the requirements of GOST 22291-83. Quartz glass, tubes, windows, prisms, lenses and other products are made both in bulk and individually.