Inorganic or fundamental glass is an important material that is used for various applications worldwide. This article describes the fundamental facts of the various types of inorganic glasses.
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Inorganic glass is an amorphous, hard, brittle, transparent, and super-cooled liquid of infinite viscosity. It is manufactured by fusing a mixture of number of metallic silicates.
The term Inorganic is added with glass because a glass is a mixture of inorganic compounds such as silicates of sodium, potassium, calcium, and lead. Only a few metallic carbonates are used for manufacturing. Although carbonates have only a little amount of carbon, carbonates of metals are studied in inorganic science. Organic compounds are not used for manufacturing any type of glass; therefore, it is called inorganic glass.
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Structure of Fundamental Inorganic Glasses
The structure fundamental inorganic glass is xR2O.yMO.6SiO2, where R is an atom of monovalent alkali metals such as Na, K, etc. and M is an atom of a bivalent metal such as Ca, Pb, Zn etc., and x and y are whole numbers.
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General Properties of Inorganic Glass
It is amorphous in nature.
It has no definite melting point.
It can absorb, reflect, and transmit light.
It can take a high polish.
It is a good electrical insulator.
It is affected by alkalis.
It is not affected by air, water, or acids or chemical reagents except HF. When it reacts with HF, the silicate component of inorganic glass converts to SiF4.
It can be formed into different articles; even it can be formed in complex shapes.
It is brittle in nature.
It is softened by heating.
It is light in weight with respect to the volume or size. This is because it has a homogeneous internal structure.
It does not have a crystal structure; due to this, it has a high compressive strength.
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Different Steps of Manufacturing Inorganic Glass
Different types of inorganic glasses are manufactured by four steps described below:
This is the processof melting raw material in proper proportions. First of all, raw materials are mixed with cullets for powdering. The powdered mixture is then sent for fusing. For fusing the mixture, different chambers are used regarding different purposes such as fireclay pots used for making high-grade glass, and tanks (a part of open- hearth furnaces) are used for low-grade glasses. The mixture melts and fuses at high temperature, about 1800 0C.
Forming and Shaping
Molten glass is then converted into desired shape either by molding or by pressing between rollers.
Glassarticles are then allowed to pass through different chambers having different temperatures, but the chambers are placed in descending order of temperature. This is designed to cool glass articles nearly to room temperature.
The glass article cannot cool rapidly because inorganic glass is a bad conductor of heat. When the article is rapidly cooled, then the superficial layer cools down first and the interior part gets high strain and the article breaks into pieces.
After the annealing process all glass articles are subjected to perform different finishing processes such as cleaning, grinding, polishing, cutting, and sand-blasting.