The nature of ceramics

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One of the first solid materials if riot the very first, that man learned to use was a ceramic natural stone. It was used in a variety of applications because of its characteristic properties such as hardness, strength to chemical attack which make it comparatively easy to shape. Thus natural ceramics provided man with tools, durable containers and even a roof. It is not surprising that man got greatly interested in ceramics and tried to create ceramics such as: pottery, bricks, concrete, glass. These products are spoken of as main industrial prod­ucts to this day.

Ceramic materials have been extended greatly. They range from dull clay to lustrous ruby, from the refractory linings to electronic control devices.

What is ceramics? Essentially it is defined as a combination of one or more definite metals with a non-metallic element, usually oxygen. The compara­tively large oxygen atoms serve as a matrix with the small metal atoms. The main characteristic of the construction of ceramic crystals is that the atoms are linked by bonds that are primarily ionic but also to a significant extent covalent. These bonds are responsible for the stability and strength of ceramic materials. In the combination of oxygen atoms with metal atoms the ionic bonds are particularly strong. It should be noted that each oxygen atom with two electronic vacancies in its outer shell borrows two electrons from its metal neighbours, thus both kinds of atoms become highly ionized – one negatively, the other positively.

As highly oxidized compounds the ceramics are strongly resistant to attack by nearly all chemicals. This accounts for many of their uses, even the making of steel depends on the use of ceramics.

A lot of analyses have been made by chemists. They found that the principal elements, for instance, in natural clays were oxygen, silicon and aluminium. They form the compounds known as aluminosilicates.

But a giant step forward in ceramic science came when crystal structures were analysed by means of X-ray diffraction. It has been found out that in the construction of ceramic materials depends much on how the atoms are stacked.

Though it is known much about ceramics many scientists work at the investigation of the properties of ceramic materials. They can be drawn into rods, cast or pressed. These ceramics are light in weight, but very strong. Some of them are so hard that they can cut steel. You can hardly find any branch of industry where ceramic products are not used. Many ceramic materials are being mass-produced now.

Дата добавления: 2014-10-31