rticle on ceramics, glass, adhesives, sealants and its chemicals history, evolution, production, industrial applications. Different types of ceramics, glass, adhesives, sealants chemicals and its properties

1. Article written and published by www.worldofchemicals.com
CHEMISTRY OF CERAMICS, GLASS, ADHESIVES
AND SEALANTS

2. CERAMICS
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Every day in our homes we are using smooth, beautiful designed
coffee cups, tea cups, plates and bowls. These should be
handled carefully and proper maintenance required. Even in
laboratories mortar and pestles lab ware manufactured by using
special kind of material. All these kind of utensils and lab ware are
made up of ceramic.
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Ceramic materials are non-metallic, inorganic compoundsprimarily compounds of oxygen, carbon, nitrogen, boron, and
silicon. Ceramics includes the manufacture of earthenware,
porcelain, bricks, sewer pipe and electrical insulators.
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Ceramics was started using in time of Neolithic time. In this 20th
centaury their uses reached to bowls to semiconductors. Some
kind of advanced ceramics include alumina ceramics are using in
missiles and rocket nose cones. Other advanced usage includes
uranium dioxide (UO2) ceramics used in nuclear power plant
elements, laser materials, ceramic capacitors, piezoelectric
materials.

3. CERAMICS MAKING PROCESS
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Ceramics is made up of clay, talc, silica, feldspar, organometallic
compounds, silicon carbide, alumina, and barium titanate.
Process
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First natural material like clay is required to be heated to high
temperatures. Clay consists of a large number of very tiny flat plates,
stacked together by thin layers of water. The water allows the plates to
attach together and allowing the plates to slide past one another. As a
result, clay is easily molded into various shapes.
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High temperatures make drying water inside the clay and allow bonds to
form between plates, holding and promoting the formation of a hard
solid. Binders such as bone ash are sometimes added to the clay to
promote sturdy bond formation, which makes the ceramic resistant to
breakage.
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Ceramic is also made by mixing clay and cements and hardening it by
heating it to high temperatures. Advanced technique of making of
ceramics used sol-gel process.

4. CERAMICS CONTAIN FOLLOWING PROPERTIES
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Chemical properties
Mechanical properties
Physical properties
Thermal properties
Electrical properties
Magnetic properties
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Chemical properties
Industrial ceramics are made up of compounds of oxygen, heavy metals,
carbon, boron, nitrogen, silicon. Ceramics do not react with most liquids, gases,
alkalies, and acids.
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Physical properties
Ceramics are smooth, lighter in weight, hard and resistance to abrasions.
Electrical properties
Ceramics are also used as insulators. Certain ceramics, such as porcelain, act
as insulators at lower temperatures but in contrast they will conduct electricity at
higher temperatures.

5. CERAMICS APPLICATIONS
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Ceramics used for making strong, hard, and
abrasion-resistant materials.
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In textile industry ceramics resist the cutting
action of fibers traveling through these guides at
high speed.
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Scientists discovered a family of
superconductive copper-oxide-based ceramics.

6. GLASS
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Besides to usage of ceramics in laboratories glass
[glassware] also used in the different laboratories. Other
places where glass is used include windscreens of cars,
windows in houses, furniture, television sets, soft drink
bottles, water drinking glass, and spectacles
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Glass is an amorphous solid material that exhibits a glass
transition. It is a state of matter in which the atoms and
molecules are locked into place, but instead of forming neat,
orderly crystals, they arrange themselves randomly.
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Glass is having similarity with ceramics in terms of their
properties like durability, strength and brittleness, high
electrical and thermal resistance, and lack of chemical
reactivity.

7. COMPOSITION OF GLASS
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Glass is made up of silica (SiO2). Following are the other components of
silica
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Sodium oxide
Magnesia
Lime
Alumina
Boric oxide
Soda (Na2O)
Lead oxide
Potassium oxide
Zinc oxide
Barium oxide
Germanium oxide

8. HISTORY OF GLASS
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First true glass was made in coastal north Syria
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The story of glass dates back to ancient Egypt where glass-making
became popular during the late Bronze Age.
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Anglo-Saxon period glass was a luxury material across England
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In 10th centaury stained glass came to usage
In 1330 crown glass was produced in Rouen
In 14th and 19th centauries stained glass employed in building purposes
In 1843 Henry Bessemer invented float glass
In 120th centaury reinforced glass and glass bricks came to usage
Colored glasses are due to inclusion of ions of chemical elements like
iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), chromium (Cr), and
manganese (Mn)

9. GLASS PREPARATION
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The main constituent of flat Glass is SiO2. This has a high melting temperature
in the region of 1700 degrees C. The basic building block of silica has a
tetrahedral pyramid shape with silicon at its centre linked symmetrically to four
oxygen atoms at its corners.
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On cooling molten silica quickly, a random organised network of these
tetrahedra is formed, linked at their corners, to give an amorphous material
known as vitreous silica.
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High melting point and viscosity of silica can be reduced by the addition of
sodium oxide. Here sodium oxide works as flux. Sodium oxide used in the form
of a carbonate and the sodium-oxygen atoms enter the silicon-oxygen network.
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These network modifiers make the structures more complex so that when the
components are melted together. In the glass making process, the cooling rate is
arranged such that viscosity increases and the mobility of the atoms are
hindered thus preventing arrangements and crystallization from occurring.

10. GLASSN APPLICATIONS
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Flat glass is used in glazing in buildings, to car
windscreens, doors and mirrors.
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Container glass extensively used in beer, wine,
spirits, juices, food, cosmetics.
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Borosilicate glass possesses good chemical and
thermal shock resistance which make it ideal for
laboratory equipment and various forms of
ovenware.

11. ADHESIVES & SEALANTS
An adhesive is a material used for holding two
surfaces together. An adhesive must wet the
surfaces, adhere to the surfaces, and by surface
attachment that resists separation.
 Inorganic substances such as portland cement
also can be considered adhesives. Natural
adhesives have been known since antiquity.
 In the performance of adhesive joints, the
physical and chemical properties of the
adhesive are the most important factors.
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12. TYPES OF ADHESIVE RAW MATERIALS
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Starch
Dextrin
Gelatin
Asphalt
Bitumen
Cellulose nitrate
Cellulose acetate
Methyl cellulose
Ethyl cellulose
Polyvinyl acetate
Polyvinyl alcohol
And more

13. MECHANISM OF ADHESION PROCESS
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The main mechanism of adhesion is explained by the
adsorption theory.
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Adsorption theory
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Adsorption theory can be defined as substances stick
because of intimate intermolecular contact. In adhesive
joints this contact is attained by intermolecular or valence
forces exerted by molecules in the surface layers of the
adhesive and adherend.
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In addition to adsorption, four other mechanisms of
adhesion have been proposed.

14. ADHESION PROCESS CONT..
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Mechanical interlocking
It occurs when adhesive flows into pores in the adherend surface
or around projections on the surface.
Interdiffusion
Interdiffusion results when liquid adhesive dissolves and diffuses
into adherend materials.
Adsorption & Surface Reaction
In this process bonding occurs when adhesive molecules adsorb
onto a solid surface and chemically react with it.
Electronic/electrostatic attraction
This theory suggests that electrostatic forces develop at an
interface between materials with differing electronic band
structures

15. SEALANTS
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A sealant is the viscous material that has little or no flow characteristics
and stay where they are applied or thin and runny so as to allow it to
penetrate the substrate by means of capillary action.
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The main difference between adhesives and sealants is that sealants
typically have lower strength and higher elongation than do adhesives.
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Sealants fall between higher-strength adhesives at one end and
extremely low-strength putties and caulks at the other. Sealants fill a gap
between two or more substrates. It forms a barrier through the physical
properties of the sealant itself and by adhesion to the substrate.
Sealants maintain sealing properties for the expected lifetime, service
conditions and environments.
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Dental sealants are a dental treatment consisting of applying a plastic
material to one or more teeth, for the purpose of preventing dental caries
(cavities) or other forms of tooth decay.