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Usage

Uses

Used in Chemical Applications:
Silica glass is used as tubing, rods, crucibles, dishes, boats, and other containers and special apparatus in both transparent and nontransparent varieties for chemical analysis and preparations. It is also used as a chromatographic substrate in the form of microparticles, capillary tubing, and open columns for high-resolution gas chromatography.
Used in Thermal Applications:
Silica glass is used to protect precious-metal thermocouples in high-temperature pyrometry, with satin tubing and transparent tubes employed for protection in reducing atmospheres.
Used in Optical Applications:
Silica glass is used for prisms, lenses, cells, windows, and other optical components where UV transmission is critical. Cuvettes used in scatter and spectrophotometer cells are manufactured from fused silica and fused quartz due to their transmissive properties and high purity.
Used in Mechanical Applications:
Silica glass is used for fibers, particularly in laboratory measurements.
Used in Electronic Applications:
Silica glass is used in electronic systems, such as radar and computers, where signal delay is necessary. A transducer converts electrical signals to ultrasonic elastic waves, which pass through a connecting medium made of silica glass to another transducer, where the waves are reconverted to electrical signals.
Used in Space and Astronomy:
Silica glass is used in space-based applications due to its static fatigue, thermal stability, and radiation resistance. It is used for windows in U.S. space vehicles, including Mercury, Gemini, Apollo, and space shuttle vehicles, to provide clarity for visual, photographic, and television-based observations.
Used in Semiconductor, New Light Source, Optical, Instrumentation, Thermal, Metallurgical, Chemical, and Building Materials Industries:
Silica glass is used in various applications across these industries, including as a material for fibers, new varieties with special properties such as ultra-low temperature expansion, and fluorescent quartz glass.
Used in Laser Technology, Space Technology, Astronomy, Nuclear Engineering, and Optical Communication:
Silica glass is utilized in these high-tech fields due to its unique optical, mechanical, and thermal properties.
Used in Concrete, Grouts, Mortars, Elastomers, Refractory, and Coating Applications:
Silica glass is suitable for these applications due to its properties.
Used in Vacuum Deposition:
Silica glass is suitable for use in vacuum deposition processes.

Physical and Chemical Properties

It has high mechanical strength, high temperature resistance, and low coefficient of thermal expansion, excellent thermal shock resistance, good chemical stability, high dielectric strength and small refractive index. It has excellent property for being penetrated by light at the range of ultraviolet, visible and infrared light regions. It has excellent low or high temperature insulation performance; An overview of the quartz glass, physical and chemical properties, preparation methods, applications, etc. are edited by Ding Hong from lookchem. (2015-11-16)

Preparation

(1) Chemical Vapor Deposition method (CVD) The silicon tetrachloride liquid is brought into the burner by the gas bubbling method, then the high temperature flame is produced by the combustion of the hydrogen-oxygen gas to hydrolyze and melt the gaseous silicon tetrachloride. After the reaction, the silicon dioxide is deposited on the substrate on. CVD deposition device can be divided into two kinds, horizontal and vertical according to the structure. In contrast, the base rod applied vertical layout inside the vertical deposition device, generating a higher deposition rate, being able to prepare large-size quartz glass. The reaction is as follows: SiCl4 (gas) + 2H2 + O2 (gas) → SiO2 ↓ + 4HCl ↑ Quartz glass synthesized by CVD method has low metal impurity content, and its performance is better than that of fused silica glass, such as high deep ultraviolet transmittance, high optical uniformity and excellent radiation resistance, which can meet the needs of some high-tech fields. However, the quartz glass prepared by the CVD method has a serious drawback: since the preparation process is always in a hydrogen excess atmosphere, the content of hydroxyl groups in the prepared quartz glass is high. The researchers generally believe that the hydroxyl group led to that infrared absorption spectrum of quartz glass has a strong absorption peak at 2.73 μm, and the presence of hydroxyl groups can also lead to lower density of quartz glass, thereby reducing its mechanical properties and thermal properties. (2) High-frequency plasma flame method The most relevant part to the synthesis process is the plasma torch part in the whole deposition device. The torch is four-tube (shown in Fig. 3): the innermost quartz glass tube is used for conveying raw material gas, the second quartz glass tube is used for conveying oxygen, The third layer of quartz glass tube is used for conveying the working gas, the outermost layer adopts the oxygen-containing gas as the cooling gas, and the high-frequency coil surrounds the outermost quartz glass tube to excite the plasma; the raw material gas transported by the inner tube, after being mixed with the oxygen transported by the second layer, enters into the plasma area for reaction, and then generate quartz glass particles to be deposited on the base for completing the process of vitrification and obtaining high-quality hydrogen-free quartz glass ingot or quartz glass mound. ? Figure 1 is the torch of four-tube quartz

References

https://www.heraeus.com/en/hqs/fused_silica_quartz_knowledge_base/properties/properties.aspx http://www.thequartzcorp.com/en/applications/quartz-glass.html

Production Methods

Modern manufacturing processes of vitreous typically involve the fusion or viscous sintering of silica particles; the particles can be derived from sand crystals or are produced through a chemical process, e.g., flame hydrolysis or sol–gel. In one practice of the flame hydrolysis process, the powder is produced and fused into glass a single step, without the isolation of a porous body. Dopant and additive profiles are concentration are then controlled by the deposition conditions. When a process involving a discrete porous silica body as an intermediate is used, subsequent processing steps can be used to control dopant levels and in particular, the hydroxyl level of the final glass. The choice of fabrication method is often dictated by the end-use specifications. Flame hydrolysis or similar chemical techniques that allow for the production of very high purity glass are the methods of choice for optical applications but may be economically wasteful for less demanding applications. Translucent Vitreous Silica. Translucent vitreous silica is produced by fusion of high purity quartz sand crystals. Sand is packed around a graphite rod through which a current is passed. The resistance heating produces a plastic mass that can be blown into molds, drawn into tubing, or shaped by rolling or pressing. Separation from the graphite rod is facilitated by gaseous products formed by interfacial reaction. Because the outside is sandy, the product is known as sand-surface ware. A matte finish is obtained by mechanical buffing. A glazed surface is produced by fusing the outside surface with an electric carbon arc or flame. Transparent Vitreous Silica. Clear, transparent, bubble-free vitreous silica may be obtained by melting natural quartz minerals by flame or plasma vapor deposition (synthetic fused silicas), and by sol–gel processing.

Hazard

Questionable carcinogen.

Safety Profile

An inhalation hazard. Questionable carcinogen with experimental tumorigenic data. Poison by intraperitoneal, intravenous, and intratracheal routes. See also other shca entries.

Potential Exposure

Amorphous fumed silica is used as a mineral, natural or synthetic fiber. A potential danger to those involved in the production and handling of fumed silica for paint pigments or catalysts. Diatomaceous earth is used in clarifying liquids, in manufacture of fire brick and heat insulators; used as a filtering agent; as a filler in construction materials; pesticides, paints, and varnishes. A potential danger to those involved in mining of diatomaceous earth or fabrication of products there from.

Incompatibilities

Silica, amorphous is a noncombustible solid. Generally unreactive chemically. Incompatible with fluorine, oxygen difluoride, chlorine trifluoride. Soluble in molten alkalis and reacts with most metallic oxides at high temperature.

Waste Disposal

Sanitary landfill.

InChI:InChI=1/O2Si/c1-3-2