Synthetic Silicate

Silicate, Synthetic

 

any of the simple or complex salts of silicic or aluminosilicic acids. Synthetic silicates are constituents of, for example, cements, refractory materials, slags, common and silica brick, porcelain and faience, glass, glazes, enamels, adsorbents, and catalysts. The synthetic silicates formed in the process of heating a starting mixture, whose composition includes, for example, SiO2, A12O3, CaO, MgO, and K20, in many ways determine the properties of the final commercial product. Synthetic silicates can also be formed as a result of undesirable processes, for example, the corrosion of refractory materials by smelted metallurgical slag. Unlike natural silicates, synthetic silicates can be prepared as single-phase products free of impurities. Nearly all analogues of natural silicates have been synthesized, as well as a large number of silicates that do not occur in nature.

Synthetic silicates of alkali metals are relatively fusible and are freely soluble in water. Silicates of Na and K in the form of water, or soluble, glass are used in the manufacture of glue, paints, and various types of putty, as well as in soapmaking. The synthetic silicates of bivalent and especially trivalent metals exhibit high refractoriness and chemical stability. The calcium silicates 3CaO • SiO2 and 2CaO•SiO2 are the basic components of portland cement. Calcium hydrosilicates, formed upon hydration of cement as well as during the hydrothermal treatment of silica brick and silicate concrete products in autoclaves, determine the strength of hardening materials. Calcium meta-silicate, CaO•SiO2, serves as a filler in paper manufacture. Magnesium orthosilicate, 2MgO•SiO2, is a basic component of for-sterite refractory materials and is also present in magnesite refractory materials and slags. Magnesium metasilicate, MgO•SiO2, forms the crystalline phase in electrically insulating steatite ceramics. The aluminum silicate mullite, 3Al2O3•2SiO2, ensures strength at high temperatures and resistance to corrosion in grog and mullite refractory materials, which are widely used in metallurgy and glassmaking. This same silicate crystallizes to form extremely slender needles upon firing of porcelain products and serves as a special reinforcement for porcelain.

Aluminosilicates of lithium and magnesium, with low thermal expansion coefficients, are basic crystalline phases of ceramic materials that are stable to thermal shock. The ability of silicate melts to solidify in glass form without crystallization makes it possible to obtain glass for various purposes. However, conditions for glass crystallization are sometimes specially created during the production process; crystalline glass materials referred to as devitrified materials are obtained as a result.

REFERENCES

Khimicheskaia tekhnologiia keramiki i ogneuporov. Edited by P. P. Budnikov and D. N. Poluboiarinov. Moscow, 1972.
Diagrammy sostoianiia silikatnykh sistem. Leningrad, 1972.

A. A. MAIER

References in periodicals archive ?
May 14, 2013 -- Researchers report that synthetic silicate nanoplatelets (also known as layered clay) can induce stem cells to become bone cells without the need of additional bone-inducing factors.
May 14, 2013--Researchers report that synthetic silicate nanoplatelets (also known as layered clay) can induce stem cells to become bone cells without the need of additional bone-inducing factors.
Use of Synthetic Silicates to Stabilize Color in Water-based Wood Stains"--Terry Brennan, Southern Clay Products
The Irvine researchers use a variation of techniques employed in making conventional synthetic silicates.
Other highlights of the symposium included: "Novel HDI-uretdiones--reactive diluents and building blocks," presented by Frank Richter, Bayer MaterialScience; "Non-yellowing catalysts for uredtione crosslinked powder coatings," presented by Bing Hsieh, King Industries; "Stabilizing colors in water-based wood stains with synthetic silicates," presented by Terrence Brennan, Southern Clay Products; "New synthetic silicas as matting agents and their effect on viscosity in waterborne coatings," presented by Hans-Dieter Christian of Degussa; and "High throughput construction of phase diagrams to guide formulation," presented by Robert Lochhead of the School of Polymers and High Performance materials, USM.