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TEXT. THE NATURE OF CERAMICS



One of .the first solid materials, if not 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 easyto 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 triedto 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? Can this question be answered? 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 much depends on how the atoms are stacked.

Ex. 1Answer the questions

1, What was the very first solid material that man began to use? 2. What did natural ceramics provide man with? 3. Why was ceramics used in a variety of applications? 4. Why did man get interested in ceramics so much? 5. What is ceram­ics? 6. What is a main characteristic of the construction of ceramic crystals? 7. Why are the ceramic materials so strongly resistant? 8. What are the principal elements in natural clays? 9. What does the construction of ceramic materials depend on? 10. Why are ceramic materials mass-produced? 11. Why is the ceramic industry so important?



 

Ex. 2Open the brackets and translate the sentences.

1. Last year our plant (produced, produces) many ceramic goods which (are used, were used) widely. 2. At first man (baked, has baked) vessels of clay in the sun. 3. Recently ceramic compounds (are used, have been used) even in making steel. 4. Numerous analyses (have been carried out, had been carried out) before they stated the exact composition of this compound. 5. Now many scientists (are working, work) at the investigation of the new properties of ceramics. 6. Many new discoveries (took place, have taken place) since the last century. 7. Last week they (analysed, analyse) crystal structure of those new materials by means of X-ray diffraction. 8. For many years considerable work (has been carried out, was carried out) to convert ethylene into motor fuel. 9. Many beautiful articles made of ceramics (provided, provides) man with tools even in ancient time.

 

Ex. 3.Find the pairs of antonyms and remember them.

hard, solid, fast, light, dull, difficult, heavy, bright, weak, easy, liquid, slow, soft, strong.

Ex. 4.Open the brackets choosing the suitable word.

1. (The very, very) first subjects we studied in the first year were mathematics, inorganic chemistry and English. 2. This was (very, the very) book I needed for my work. 3. Have you (found out, found) what subject he was interested in? 4. I shall use this new material (provide, provided) it is resistant to corrosion. 5. She could (hardly, hard) use this material as it was too brittle. 6. These ceramic materials are (light, heavy) in weight. 7. This solid material was (very, the very) good for construction.

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Ex. 5 Translate the text paying attention to the use of the word “very”.

Pottery, porcelain, brick and tile are all very similar in composition and method of manufacture, and with glass they provide the class of materials known as ceramics. These products are made from varying mixtures of clay, silica, and feldspar.

The very first of them are usually prepared from natural clays which already contain silica and feldspar. These natural clays are made into a workable mud with water and then fired in special ovens. As the temperature rises, water is first driven from the mixture, then various decomposition products are formed and above 1250° C the feldspar fuses and binds the other materials present.

Porcelain is made from a very fine white clay known as kaolin. Then very pure sands and feldspars are added. Very soft porcelain is obtained if one adds calcium phosphate to the mud.

Ex. 6 Translate the text

Glass

Silicate materials include glass, porcelain, enamels and cement.

Ordinary glass is a mixture of silicates in the form of supercooled liquid. It is made by melting a mixture of sodium carbonate (or sodium sulphate), limestone and sand.

Ordinary glass contains about 10% sodium, 5% calcium, and 1% aluminum, the remainder is silicon and oxygen. It consists of an aluminosilicate tetrahedral framework, within which are embedded sodium ions and calcium ions.

Cement

Portland cement is an aluminosilicate powder which sets to a solid mass on treatment with water. Portland cement before treatment with water consists of a mixture of calcium silicates and calcium aluminate. When treated with water the calcium aluminate hydrolyzes and forms calcium hydroxide and aluminum hydroxide. These substances react further with the calcium silicates and produce calcium aluminosilicates in the form of crystals.

 

WORD-BUILDING

Конверсія.

master (хазяїн) - to master (керувати), house (дім) - to house (розміщувати), water (вода) - to water (поливати), empty (пустий) - to empty (спустошувати) white (білий) - to white (білити).

Словоскладання.

airfield - аеродром (air - повітря, field - поле), airbase - авіабаза (air - повітря, base - база), airman - авіатор (air - повітря, man - чоловік), schoolday - шкільний день (school - школа, day - день), birthplace - місце народження (birth народження -, place - місце). service dress - формений одяг, одяг для служби (service - служба, dress - сукня), shop window - вітрина (shop - магазин, window – вікно)

Зміна наголосу.

export (експорт) - to export (експортувати) present (подарунок) - to present (дарувати).





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