46 Модульна контрольна робота №6

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Refrigerant and the way it works
A refrigerator systems basic ingredient is a singular substance called a refrigerant which boils and condenses (changes from liquid to vapor and vice versa) at freezing temperatures. Early machines used Sulphur dioxide as a refrigerant. Now most home refrigerators use fluocarbon refrigerant which is designed especially for the job.
Many years ago a refrigerating machine was a far cry from today’s sleek machines, but the basic ingredient was the same.
And now, do you want to know how the refrigerator works. It is to let the cold liquid-fluocarbon absorb heat from the inside. The heat boils the fluocarbon and turns it into a vapor – which gives up the heat while being liquefied. As a liquid fluocarbon is sent back to the freezer, ready to pick up more heat.
Text 7
METALS

Metals are materials most widely used in industry be¬cause of their properties. The study of the production and properties of metals is known as metallurgy.
The separation between the atoms in metals is small, so most metals are dense. The atoms are arranged regu¬larly and can slide over each other. That is why metals are malleable (can be deformed and bent without frac¬ture) and ductile (can be drawn into wire). Metals vary greatly in their properties. For example, lead is soft and can be bent by hand, while iron can only be worked by hammering at red heat.
The regular arrangement of atoms in metals gives them a crystalline structure. Irregular crystals are called grains. The properties of the metals depend on the size, shape, orientation, and composition of these grains. In general, a metal with small grains will be harder and stronger than one with coarse grains.
Heat treatment such as quenching, tempering, or annealing controls the nature of the grains and their size in the metal. Small amounts of other metals (less than 1 per cent) are often added to a pure metal. This is called alloying (легирование) and it changes the grain struc¬ture and properties of metals.
All metals can be formed by drawing, rolling, ham¬mering and extrusion, but some require hot-working. Metals are subject to metal fatigue and to creep (the slow increase in length under stress) causing deformation and failure. Both effects are taken into account by engineers when designing, for example, airplanes, gas-turbines, and pressure vessels for high-temperature chemical proc¬esses. Metals can be worked using machine-tools such as lathe, milling machine, shaper and grinder.
The ways of working a metal depend on its properties. Many metals can be melted and cast in moulds, but spe¬cial conditions are required for metals that react with air.
Vocabulary:

property — свойство
metallurgy — металлургия
separation — разделение, отстояние
dense — плотный
arrangement — расположение
regularly — регулярно, правильно
to slide — скользить
malleable — ковкий, податливый, способ¬ный деформироваться
bent pp of bend — гнуть
to fracture — ломать
ductile — эластичный, ковкий
to draw — волочить, тянуть
wire — проволока
lead — свинец
iron — железо, чугун
grain — зерно
to depend — зависеть
size — размер, величина
shape — форма, формировать
composition — состав
coarse — грубый, крупный
treatment — обработка
quenching — закалка
tempering — отпуск после закалки, нор¬мализация
annealing — отжиг, отпуск
rolling — прокатка
to hammer — ковать (напр. молотом)
extrusion — экструзия
metal fatigue — усталость металла
creep — ползучесть
stress — давление,
failure — повреждение, разрушение
vessel — сосуд, котел, судно
lathe — токарный станок
milling machine — фрезерный станок
shaper — строгальный станок
grinder — шлифовальный станок
to melt — плавить, плавиться расплавить
to cast — отливать, отлить
mould — форма (для отливки)


General understanding:

1. What are metals and what do we call metallurgy?
2. Why are most metals dense?
3. Why are metals malleable?
4. What is malleability?
5. What are grains?
6. What is alloying?
7. What is crystalline structure?
8. What do the properties of metals depend on?
9. What changes the size of grains in metals?
10. What are the main processes of metal forming?
11. How are metals worked?
12. What is creeping?


Exercise 1.1. Find the following words and word combinations in the text:

1. Свойства металлов
2. расстояние между атомами
3. правильное расположение
4. сильно отличаются по своим свойствам
5. кристаллическая структура
6. размер зерен
7. форма зерен
8. закалка
9. отжиг
10.волочение
11.прокатка
12.ковка
13.экструзия
14. структура и свойства зерна
15. горячая обработка
16. усталость металла
17. ползучесть металла
18. плавка и отливка в формы
19. способы обработки металлов

Exercise 1.2. Complete the following sentences:

1. Metals are...
2. Metallurgy is...
3. Most metals are...
4. The regular arrangement of atoms in metals...
5. Irregular crystals...
6. The properties of the metals depend...
7. Metals with small grains will be...
8. ...controls the nature of the grains in the metal.
9. Alloying is...
10. All metals can be formed by...
11. Creep is...
12. Metals can be worked using...


Exercise 1.3. Explain in English the meaning of the following words:

Навчимось

Heating and cooling system mechanics install and repair heating air conditioning and refrigerating systems in homes, schools and commercial buildings. Heating and cooling system mechanics work on equipment ranging from private homes units to large and complex systems in factories. They diagnose problems, make adjustments, and set up components, such as: motors, pumps and solar collectors. They install such parts as air duets and fuel pumps, and connect equipment to a power source. Installers and mechanics may crawl into attics and under houses.
Heating and cooling system mechanics work indoors and outdoors. They generally work a five-day, 40-hour week, with evening and weekend work during emergencies. Overtime work is common during busy seasons (summer and winter). Mechanics may spend all of the working day away from the shop working alone. The demand for heating and cooling system mechanics generally follows trends in the construction of: 1) Commercial; 2) Industrial; 3) Residential buildings. This profession has some safety hazards. Mechanics may be exposed to noise, fumes and hazards, such as: electrical shock and muscle strain.

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