10. Answer the following questions

1. What do mechanical engineers need to know for making products?

2. What can determine mechanical properties?

3. Why is aluminum used in foils, such as food wraps?

4. What materials are usually very dense or compact?

5. What mechanical property must the metal used to make airplanes have?

6. What physical property of material is one of the most fundamental?

7. What chemical properties of materials do you know?

8. What are electrical properties?

9. How do materials react to heat?

10. What materials are attracted to magnets?

11. What are physical properties of materials?

11. Make a plan of the text

12. Translate the part of the text in italics in a written form

13. Retell the text according to your plan Text c. The materials cycle and the role of materials science and engineering

Glossary

beneficiation [͵benifiʹkei∫(ə)n] n - збагачення

energy consumption [ʹenədʒi][kənʹsʌmp∫(ə)n] n - згоряння енергії

pulping [ʹpʌlpiŋ] n - подрібнення, перетворення в м'яку масу

purification [͵pjuərifiʹkei∫(ə)n] n - очищення

refining [riʹfainiŋ] n - рафінація, перегонка

to consume [kənʹsju:m] v - споживати

to take smth for granted - прийняти щось як належне

wide-spread [ʹwaidspred] adj - широко розповсюджений

14. Listen to the text “The Materials Cycle and the Role of Materials science and Engineering” and define if the statements are true or false

1. Materials are substances having properties which don’t make them useful in machines, structures, devices and products.

2. Every stage of the cycle consumes energy.

3. The engineering materials are fashioned into shapes and parts to make a useful end-product.

4. The materials cycle is an isolated structure.

15. Listen to the text once more and give the answers to the questions

1. What role do materials play in all manufacturing industries and in much research and development in the physical and engineering sciences?

2. What are minerals and oils taken from?

3. What are the main processes of convertation raw materials into useful industrial materials?

4. Can the materials cycle affect the environment?

5. Why is it necessary for the specialist in Materials Science and engineering to consider the effect of technological changes on the complete system of the total materials cycle?

Unit 11 Text a. Non-metallic materials. Engineering plastics and glasses

1. Read and translate the text using the glossary

The engineering mechanic should become familiar with a few plastics, a few ceramics, a few tool steel, and so on; it will be found that these will satisfy maybe 90% of engineering needs. Save the remaining 10% of material problems for the metallurgist.

There are non-metallic and metallic materials. The usage of materials depends on their properties, availability, economics factors.

Such non-metallic materials as plastics, polymers, glass are widely used in engineering. And though mechanical properties of non-metallic materials are usually significantly lower than those of metals, non-metallic materials are the most economical.

Technical development states that plain bearings are the major plastic engineering application. Plastic wear components are widely used in the design of rolling elements, slides, cams, gears, casters, detents, and hundreds of other specific machine components.

In the case of glass-or asbestos-filled or reinforced plastics, the hardest possible mating surface is a mandate for good service life.

The importance of the use of polymers for protective and decorative coatings is obvious. Polymers are the highest corrosion-resistant materials. Adhesives, a powerful application of polymeric materials, can be used to simplify many designs and fabrication procedures.

The high-silica glasses have excellent thermal shock resistance. These glasses can be heated red hat and water quenched without cracking. Glass fibers are used in insulation, sound deadening. Glasses can be used to shield or to transmit radiation. Photosensitive glasses are chemically machined into intricate shapes for fluidic devices used in machine controls.

Engineering plastics. Though polymers are widely used in coating, adhesives, and elastomers, every engineer must know that, unlike metals, polymers have properties that vary significantly with moderate temperatures and loads. The following are some of specific features of plastics to be considered in the design of load-bearing members:

• Plastics, or more correctly polymeric materials, expand with temperature at a rate many times greater than a metal.

• The stiffness of plastics is an order of magnitude lower than the stiffness of metals.

• Plastics permanently deform under load at room temperature and at stresses below their yield strength.

• Some plastics are flammable.

• Some plastics can absorb significant amounts of moisture and change size.

• Fatigue data are not readily available.

Engineering glasses. Traditionally glasses are defined as super-cooled liquids. This is because glasses do not behave like metals, ceramics, or even plastics on cooling from the molten condition. Most glasses are considered to be just a very viscose liquid when it is a solid. The properties of glasses very with composition, but some general statements can be made:

• Glasses are harder than many metals.

• Glasses have low ductility; they are brittle.

• Glasses have a low coefficient of thermal expansion compared with many metals and plastics.

• Glasses have low thermal conductivity.

• Glasses can be good electrical insulators.

• Glasses are resistant to many acids, solvents, and chemicals.

• Glasses can be used at elevated temperature (up to 820^oC/1508^oF)

• Glasses are slowly attacked by water.

So, engineering glasses have good mechanical properties, and a wide range of thermal, electrical and optical properties. They have many uses in machines.

Glossary

аbrasive [əʹbreisiv] n - шліфувальний матеріал

absorb [əbʹsƆ:b] v - поглинати

adhesive [ədʹhi:siv] n - матеріал, що зв’язує

application [͵æpliʹkei∫(ə)n] n - застосування

boron [ʹbƆ:rƆn]  n - бор

cam [kæm] n - кулачок, кулачковий диск

caster [ʹka:stə] n - ливарник, ролик

clay [klei] n - глина

cutting [ʹkʌtiŋ] tool n - ріжучий інструмент

deaden [ʹdedn] v - ослабляти, заглушати

detent [diʹtent] n - клямка, гачок

elastomer [iʹlæstəmə] n - еластомер

elevated [ʹeliveitid] (temperature) adj - висока (температура)

expansion [iksʹpæn∫(ə)n] n - розширення

flammable [ʹflæməbl] adj - легкозаймистий

gear [giə] n - шестерня, зубчаста передача

germanium [dʒə: ʹmeiniəm]   n германій

grind [graind] v - шліфувати, полірувати

insulation [insjuʹlei∫(ə)n] -  n ізоляція, ізоляційний матеріал

intricate [ʹintrikit] (shape) adj - скляна (форма)

metalloid [ʹmetəlƆid] n - неметал

moderate [ʹmƆd(ə)rit] (temperature) adj - помірна (температура)

molten [ʹməult(ə)n] (condition) adj - розплавлений (стан)

plain bearing [ʹbeəriŋ] n - підшипник ковзання

rolling element n – роликовий елемент

quench [kwent∫]  v - загартувати

reinforced [ri:inʹfƆ:st] adj - підвищеної міцності (жорсткості)

roll [rəul] v - вертіти, обертати

shield [∫i:ld] v - заслоняти, пропускати

shock resistance [∫Ɔk] [riʹzist(ə)ns] n - опір, протидія удару, поштовху, стійкість

silicon [ʹsilikən] n - кремній

slide [slaid] n - ковзна частина механізму, повзун, каретка

stiffness [ʹstifnis] n - жорсткість

transmit [trænzʹmit] v - проводити, пропускати

wear [weə] component n – запчастина зносу

yield [ji:ld] strength n - межа міцності на текучість