Famous people of science and engineering

George Stephenson

George Stephenson was a British inventor and engineer. He is famous for building the first practical railway locomotive.

Stephenson was born in 1781 in Wylam, near Newcastle upon Tyne, Northumberland. During his youth he worked as a fireman and later as an engineer in the coal mines of Newcastle. He invented one of the first miner's safety lamps independently of the British inventor Humphry Davy. Stephenson's early locomotives were used to carry loads in coal mines, and in 1823 he established a factory at Newcastle for their manufacture. In 1829 he designed a locomotive known as the Rocket, which could carry both loads and passengers at a greater speed than any locomotive constructed at that time. The success of the Rocket was the beginning of the construction of locomotives and the laying of railway lines.

Robert Stephenson, the son of George Stephenson was a British civil engineer. He is mostly well-known known for the construction of several notable bridges.

He was born in 1803 in Willington Quay, near Newcastle upon Tyne, and educated in Newcastle and at the University of Edinburgh. In 1829 he assisted his father in constructing a locomotive known as the Rocket, and four years later he was appointed construction engineer of the Birmingham and London Railway, completed in 1838. Stephenson built several famous bridges, including the Victoria Bridge in Northumberland, the Britannia Bridge in Wales, two bridges across the Nile in Damietta in Egypt and the Victoria Bridge in Montreal, Canada. Stephenson was a Member of Parliament from 1847 until his death in 1859.

UNIT 5

PLASTICS

I. Text A: «Plastics», Text B: «Types of plastics», Text C: «Composite Materials»

II. Famous People of Science: Alfred Bernhard Nobel.

Text A: «PLASTICS»

Plastics are non-metallic, synthetic, carbon-based materials. They can be moulded, shaped, or extruded into flexible sheets, films, or fibres. Plastics are synthetic polymers. Polymers consist of long-chain molecules made of large numbers of identical small molecules (monomers). The chemical nature of a plastic is defined by the monomer (repeating unit) that makes up the chain of the polymer. Polyethene is a polyolefin; its monomer unit is ethene (formerly called ethylene). Other categories are acrylics (such as polymethylmethacrylate), styrenes (such as polystyrene), vinys (such as polyvinyl chloride (PVC)), polyesters, polyurethanes, polyamides (such as nylons), polyethers, acetals, phenolics, cellulosics, and amino resins. The molecules can be either natural — like cellulose,wax, and natural rubber — or synthetic — in polyethene and nylon. In co-polymers, more than one monomer is used.

The giant molecules of which polymers consist may be linear,branched, or cross-linked, depending on the plastic. Linear and branched molecules are thermoplastic (soften when heated), whereas cross-linked molecules arethermosetting (harden when heated).

Most plastics aresynthesized from organicchemicalsor from natural gas or coal. Plastics are light-weight compared to metals and are good electrical insulators. The best insulators now are epoxy resins and teflon. Teflon or polytetrafluoroethene (PTFE) was first made in 1938 and was produced commercially in 1950.

Plastics can be classified into several broad types.

1. Thermoplastics soften on heating, thenharden again when cooled. Thermoplastic molecules are alsocoiled and because of this they are flexible and easilystretched.

Typical example of thermoplastics is polystyrene. Polystyrene resins are characterized by high resistance to chemical and mechanical stresses at low temperatures and by very low absorption of water. These properties make the polystyrenes especially suitable for radio-frequency insulation and for parts used at low temperatures in refrigerators and in airplanes. PET (polyethene terephthalate) is a transparent thermoplastic used for soft-drinks bottles. Thermoplastics are also viscoelastic, that is, they flow (creep) under stress. Examples are polythene, polystyrene andPVC.

2. Thermosetting plastics (thermosets) do not soften when heated, and with strong heating they decompose. In most thermosets final cross-linking, which fixes the molecules, takes place after the plastic has already been formed.

Thermosetting plastics have a higher density than thermoplastics. They are less flexible, more difficult to stretch, and are lesssubjected to creep. Examples of thermosetting plastics include urea-formaldehyde or polyurethane and epoxy resins, most polyesters, and phenolic polymers such as phenol-formaldehyde resin.

3. Elastomers are similar to thermoplastics but have sufficient cross-linking between molecules topreventstretching and creep.

Vocabulary:

carbon — углерод

flexible— гибкий

fibre— волокно, нить

chain— цепь

identical— одинаковый, идентичный

molecule— молекула

branch — разветвленный

to synthesize — синтезировать

chemicals — химические вещества

to soften — смягчать

cellulose — клетчатка, целлюлоза

wax — воск

thermosetting plastics — термореактивные пластмассы

to harden — делать твердым

coil — спираль

stretched — растянутый

transparent — прозрачный

rubber — резина, каучук

to decompose — разлагаться

soft-drink — безалкогольный напиток

to subject — подвергать

polyurethane — полиуретан

resin — смола

similar — сходный, подобный

sufficient — достаточный

to prevent — предотвращать

General understanding

1. What is the definition of plastics?

2. What is the basic chemical element in plastics formula?

3. What do polymers consist of?

4. What are long-chain molecules made of?

5. What are the main types of polymers?

6. Give examples of plastics belonging to these types.

7. What plastics are the best electrical insulators?

8. Describe the difference between thermoplastics and thermosets.

9. What are the main types of structures of polymers?

10. What are the most important properties of plastics?

11. Give the examples of various uses of plastics because of their characteristic properties.

Exercise 5.1. Find English equivalents in the text:

1. синтетические полимеры

2. молекулы с длинными цепями

3. характерные свойства полимера

4. синтезируются из органических химических веществ

5. хороший электрический изолятор

6. размягчаться при нагревании

7. затвердевать при охлаждении

8. гибкий и легко растяжимый

9. течь под нагрузкой

10. более высокая плотность

11. менее подвержены ползучести

12. достаточная взаимосвязь между молекулами

Exercise 5.2. Translate into English:

1. Длинные цепи молекул полимеров состоят из одинаковых небольших молекул мономеров.

2. Сополимеры состоят из двух и более мономеров.

3. Пластмассы можно получать в виде листов, тонких пленок, волокон или гранул.

4. Молекулы полимеров могут быть линейными, ветвящимися или с поперечными связями.

5. Малый вес пластмасс и хорошие электроизоляционные свойства позволяют использовать их в радиоэлектронике и электроприборах, а также вместо металлов.

6. Молекулы термопластов имеют извитую форму и, поэтому, они гибкие и легко растяжимы.

7. Эластомеры имеют большое число поперечных связей между молекулами.

Text В: «TYPES OF PLASTICS»

Epoxy resin.

Epoxy resin is a thermoset plastic containing epoxy groups. Epoxy resin hardens when it is mixed with solidifier and plasticizer. Plasticizers make a polymer more flexible.

Epoxy resins have outstandingadhesion, toughness, and resistance to attack from chemicals. They form strongbonds and have excellent electricalinsulationproperties. Large, complex,void-free castings can be made from them. They are also used as adhesives, and in composites for boat building and sports equipment.

2. PVC (polyvinyl chloride)

PVC (polyvinyl chloride) is a thermoplastic polymer made from vinyl chloride is a colourlesssolid with outstanding resistance to water, alcohols, and concentratedacids andalkalis. It is obtainable as granules, solutions, lattices, andpastes. When compounded with plasticizers, ityields a flexible material moredurable thanrubber. It is widely used for cable and wireinsulation, in chemical plants, and in the manufacture of protectivegarments. Blow moulding of unplasticized PVC produces clear, tough bottles which do not affect the flavour of their contents. PVC is also used for production of tubes or pipes.

Polystyrene.

Polystyrene is a thermoplastic produced by the polymerization of styrene. The electrical insulating properties of polystyrene are outstandingly good and it is relatively unaffected by water. Typical applications include lightfixtures, toys, bottles,lenses, capacitordielectrics, medicalsyringes, andlight-duty industrial components. Extruded sheets of polystyrene are widely used for packaging,envelope windows, and photographic film. Its resistance toimpact can beimproved by the addition of rubbermodifiers. Polystyrene can bereadily foamed; the resulting foamed polystyrene is usedextensively for packaging.

4. Polythene (polyethene, polyethylene)

Polythene (polyethene, polyethylene) is a plastic made from ethane. It is one of the most widely used important thermoplastic polymers. It was first developed by the polymerization of ethane at a pressure of 2,000 bar at 200°C. This produced low-density polythene (LDPE). A relatively high-density form (HDPE) was synthesized in the 1950s using a complexcatalyst. Polythene is a whitewaxy solid with very low density,reasonable strength and toughness, but low stiffness. It is easily moulded and has a wide range of uses in containers, packaging,pipes, coatings, and insulation.

Vocabulary:

adhesion— прилипание

adhesive — клей

bond — связи, узы

insulation — изоляция

casting — литье

void — пустота

solid — твердое тело, твердый

acid — кислота

alkali — щелочь

to obtain — доставать, получать

granule— гранула

solution — раствор

lattices — латексы

paste— паста

yield— выход

durable — прочный

rubber— резина, каучук

garment — предметы одежды

lens —линза

capacitor — эл. конденсатор

syringe— шприц

light-duty — неответственный

envelope — зд. обрамление

impact — удар

improved — улучшенный

modifiers — модификаторы

addition — добавление

readily — легко, с готовностью

foam — пена

catalyst — катализатор

wax — воск

reasonable — приемлемый, неплохой

coating — слой, покрытие

General understanding:

1. What are the types of plastics?

2. What are the features of the epoxy resin?

3. What is epoxy resin used for?

4. What is PVC usually used for?

5. What are the typical applications of polystyrene?

6. When was polyethylen synthesized?

7. Under what conditions is polyethylen synthesized?

8. What sorts of polyethylen can be synthesized?

Exercise 5.3. Translate into Russian:

1. Polythene is a plastic made from ethane.

2. Epoxy resins have outstanding adhesion, toughness and resistance to attack from chemicals.

3. PVC is a colourless solid with outstanding resistance to water, alcohols, and concentrated acids and alkalis.

4. Polystyrene is a thermoplastic produced by the polymerization of styrene.

5. Polythene is a white waxy solid with very low density, reasonable strength and toughness but low stiffness.

Exercise 5.4. Translate into English:

1. Эпоксидная смола затвердевает когда смешивается с отвердителем и пластификатором.

2. Эпоксидные смолы используются в качестве клея, а с добавками — в строительстве лодок и спортивного снаряжения.

3. ПВХ — бесцветное твердое вещество с выдающейся устойчивостью к воздействию воды, спиртов, концентрированных кислот и щелочей.

4. ПВХ широко используется при производстве изоляции для проводов.

5. Выдувка непластифицированного ПВХ используется при производстве прозрачных бутылок для напитков.

6. Полистирол легко вспенивается и используется для упаковки.

7. Полиэтилен — воскообразное вещество белого цвета с очень низкой плотностью и малой жесткостью.

Text С: «COMPOSITE MATERIALS»

The combinations of two or more different materials are called composite materials. They usually have unique mechanical and physical properties because they combine the best properties of different materials. For example, afibre-glass reinforced plastic combines the high strength of thin glassfibres with the ductility and chemical resistance of plastic. Nowadays composites are being used for structures such as bridges, boat-building etc.

Composite materials usually consist of synthetic fibres within a matrix, a material that surrounds and is tightly bound to the fibres. The most widely used type of composite material ispolymer matrix composites(PMCs). PMCs consist of fibres made of a ceramic material such as carbon or glass embedded in a plastic matrix. Usually the fibres make up about 60 per cent by volume. Composites with metal matrices or ceramic matrices are calledmetal matrix composites (MMCs) andceramic matrix composites (CMCs), respectively.

Continuous-fibre composites are generally required for structural applications. Thespecific strength(strength-to-density ratio) andspecific stiffness (elastic modulus-to-density ratio) of continuous carbon fibre PMCs, for example, can be better than metal alloys have. Composites can also have other attractive properties, such as high thermal or electrical conductivity and a low coefficient of thermalexpansion.

Although composite materials have certain advantages over conventional materials, composites also have some disadvantages. For example, PMCs and other composite materials tend to be highlyanisotropic— that is, their strength, stiffness, and other engineering properties are different depending on the orientation of the composite material. For example, if a PMC is fabricated so that all the fibres are lined up parallel to one another, then the PMC will be very stiff in the direction parallel to the fibres, but not stiff in the perpendicular direction. The designer who uses composite materials in structures subjected to multidirectional forces, must take these anisotropic properties into account. Also, forming strong connections between separate composite material components is difficult.

The advanced composites have high manufacturing costs. Fabricating composite materials is a complex process. However, new manufacturing techniques are developed. It will become possible to produce composite materials at higher volumes and at a lower cost than is now possible, accelerating the wider exploitation of these materials.

Vocabulary:

fibreglass— стекловолокно

fibre — волокно, нить

reinforced — упрочненный

expansion — расширение

matrix — матрица

ceramic — керамический

specific strength — удельная прочность

specific stiffness — удельная жесткость

anisotropic — анизотропный

General understanding:

1. What is called «composite materials»?

2. What are the best properties of fibre-glass?

3. What do composite material usually consist of?

4. What is used as matrix in composites?

5. What is used as filler or fibers in composites?

6. How are the composite materials with ceramic and metal matrices called?

7. What are the advantages of composites?

8. What are the disadvantages of composites?

9. Why anisotropic properties of composites should be taken into account?

Exercise 5.5. Find equivalents in the text:

1. композитные материалы

2. уникальные механические качества

3. полимерные матричные композиты

4. составлять 60% объема

5. углепластик

6. привлекательные качества

7. структура, подвергающаяся воздействию разнонаправленных сил

Exercise 5.6. Translate into Russian:

1. PMC is fabricated so that all the fibres are lined up parallel to one another.

2. Forming strong connections between separate composite material components is difficult.

3. Fabricating composite materials is a complex process.

4. Composite materials have certain advantages over conventional materials

5. Nowadays, composites are being used for structures such as bridges, boat-building etc.

6. Continuous-fibre composites are generally required for structural applications.

FAMOUS INVENTORS

Alfred Bernhard Nobel was a famous Swedish chemist and inventor. He was born in Stockholm in 1833. After receiving an education in St. Petersburg, Russia, and then in the United States, where he studied mechanical engineering, he returned to St. Petersburg to work with his father in Russia. They were developing mines, torpedoes, and other explosives.

In a family-owned factory in Heleneborg, Sweden, he developed a safe way to handle nitroglycerine, after a factory explosion in 1864 killed his younger brother and four other people. In 1867 Nobel achieved his goal: he produced what he called dynamite динамит. Не later produced one of the first smokeless powders (порох). At the time of his death he controlled factories for the manufacture of explosives (взрывчатое вещество) in many parts of the world. In his will he wanted that the major portion of his money left became a fund for yearly prizes in his name. The prizes were to be given for merits (заслуги) in physics, chemistry, medicine and physiology, literature, and world peace. A prize in economics has been awarded since 1969.

UNIT 6

WELDING

I. Text A: «Welding», Text В: «Other types of welding»

II. Famous People of Science and Technology: James Prescott Joule.

Text A: «WELDING»

Welding is a process when metal parts arejoined together by the application of heat, pressure, or a combination of both. The processes of welding can be divided into two main groups:

• pressure welding, when the weld isachieved by pressure and

• heat welding, when the weld is achieved by heat. Heat welding is the most common welding process used today.

Nowadays welding is usedinstead of bolting andriveting in the construction of many types of structures, including bridges, buildings, and ships. It is also abasicprocess in themanufacture of machinery and in the motor and aircraft industries. It is necessary almost in all productions where metals are used.

The welding processdepends greatly on the properties of the metals, thepurpose of their application and theavailable equipment. Welding processes are classified according to thesources of heat and pressure used.

The welding processes widely employed today include gas welding, arc welding, and resistancewelding. Other joining processes arelaser welding, andelectron-beam welding.

Gas Welding

Gas welding is a non-pressure process using heat from a gasflame. The flame is applied directly to the metal edges to be joined andsimultaneously to a filler metalin the form ofwire or rod, called the welding rod, which ismelted to thejoint.Gas welding has theadvantage of using equipment that is portable and does notrequire an electric power source. Thesurfaces to be welded and the welding rod arecoated withflux, afusible material that shields the material from air, which would result in a defective weld.

Arc Welding

Arc-welding is the most important welding process for joining steels. It requires a continuous supply of either direct or alternating electrical current. This current is used tocreate an electric arc, which generates enough heat to melt metal and create a weld.

Arc welding has several advantages over other welding methods. Arc welding is faster because the concentration of heat is high. Also, fluxes are not necessary in certain methods of arc welding. The most widely used arc-welding processes areshielded metal arc, gas-tungsten arc, gas-metal arc, andsubmerged arc.

Shielded Metal Arc

In shielded metal-arc welding, a metallic electrode, which conducts electricity, is coated with flux and connected to a source of electric current. The metal to be welded is connected to the other end of the same source of current. An electric arc is formed bytouching thetipof the electrode to the metal and then drawing it away. The intense heat of the arc melts both parts to be welded and the point of the metal electrode, which suppliesfillermetal for the weld. This process is used mainly for welding steels.

Vocabulary:

to join — соединять

pressure welding — сварка давлением

heat welding — сварка нагреванием

instead — вместо, взамен

bolting — скрепление болтами

riveting — клепка

basic — основной

to manufacture — изготовлять

to depend — зависеть от

purpose — цель

available — имеющийся в наличии