TOPIC 6. MATERIAL TYPES

Text 1

 

1.Прочитайте слова по транскрипции:

iron |ˈaɪən|, hydrogen |ˈhʌɪdrədʒ(ə)n|, alloy |ˈælɔɪ|, chromium |ˈkrəʊmɪəm|, manganese |ˈmaŋɡəniːz|, tungsten |ˈtʌŋst(ə)n|.

 

2.Обратите внимание на перевод следующих слов и словосочетаний:

iron - чёрный металл;

copper - медь;

carbon - углерод;

silicon - кремний;

ferrous metals - чёрные металлы;

non-ferrous metals - цветные металлы;

aluminium - алюминий;

chemically bound - химически связанный;

hydrogen - водород;

oxygen - кислород;

alloy - сплав;

steel - сталь;

iron-carbon alloy - железо-углеродистый сплав;

chromium - хром;

manganese - марганец;

tungsten - вольфрам.

 

3.Прочитайте текст и переведите при помощи словаря незнакомые слова и словосочетания.

 

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MATERIAL TYPES

Engineering materials can be divided into:

• metals- examples of metallic materials are iron (Fe) and copper (Cu)

• non-metals- examples of non-metallic materials are carbon (C) and silicon (Si).

As iron is such a widely used material, metals can be divided into:

• ferrous metals- those that contain iron;

• non-ferrous metals- those that do not contain iron.

  With regard to the chemical composition of materials -the chemicals they contain, and how those chemicals are combined- three main categories can be used:

• Elements are pure materials in their most basic form. They cannot be broken down into different constituents ('ingredients'). Examples of elements widely used in engineering materials are iron, carbon and aluminium (AI).

• Compounds consist of two or more elements that are chemically bound - that is, combined by a chemical reaction. An everyday example is water, which is a compound of hydrogen (H) and oxygen (0).

• Mixtures consist of two or more elements or compounds which are mixed together, but which are not chemically bound. In engineering, common examples are alloys -that is, metals which have other metals and/or non-metals mixed with them.

A common example is steel, which is an iron-carbon alloy, and can include other alloying metals- metals which are added to alloys, in small quantities relative to the main metal. Examples of widely used alloying metals are chromium (Cr), manganese (Mn) and tungsten (W).

 

5.Скажите, являются ли данные утверждения верными или неверными (true or false):

1 The elements that make up a compound are chemically bound.

2 Alloys are chemical compounds that are frequently used in engineering.

3 Alloys can contain both metallic and non-metallic constituents.

4 In an alloy, an alloying metal is the biggest constituent, by percentage.

5 Steel is a metallic element.

 

Text 2

 

1.Прочитайте слова по транскрипции:

significant |sɪɡˈnɪfɪk(ə)nt|, quantity |ˈkwɒntɪti|, approximately |əˈprɒksɪmətli|, molybdenum |məˈlɪbdənəm|, cobalt |ˈkəʊbɔːlt|, deteriorate |dɪˈtɪərɪəreɪt|, oxidizing |ˈɒksɪdaɪzɪŋ|.

 

2.Обратите внимание на перевод следующих слов и словосочетаний:

steel - сталь;

alloy - сплав;

carbon steel - углеродистая сталь;

mild steel - мягкая сталь; малоуглеродистая сталь;

medium carbon steel - среднеуглеродистая сталь;

alloy steel -     легированная сталь;

chromium -     хром;

nickel - никель;

manganese - марганец;

molybdenum – молибден;

vanadium - ванадий;

stainless steel - нержавеющая сталь;

tool steel - инструментальная сталь;

corrode - ржаветь; подвергаться действию коррозии;

iron oxide -     окись железа;

 

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STEEL

 Steel is the most widely used engineering material. Technically, though, this well-known alloy of iron and carbon is not as simple as one might think. Steel comes in a huge range of different grades, each with different characteristics. For the inexperienced, it can be difficult to know where to begin.

 A good place to start is with the two main types of steel. The first, carbon steels, consist of iron and carbon, and contain no significant quantities of other metals. Carbon steels can be divided into three main grades:

• Mild steel - the most widely used grade - is a low carbon steel which contains up

to approximately 0.3% carbon.

• Medium carbon steel contains between approximately 0.3% and 0.6% carbon.

• High carbon steel contains between approximately 0.6% and 1.4% carbon.

 The second main category of steel is alloy steels, which consist of iron, carbon and one or more alloying metals. Specific grades of alloy steel include:

• low alloy steels, which contain 90% or more iron, and up to approximately 10% of alloying metals such as chromium, nickel, manganese, molybdenum and vanadium • high strength low alloy steels (HSLA), which contain smaller quantities of the

above metals (typically less than 2%)

• stainless steels, which contain chromium as well as other metals - such as nickel -

and which do not rust.

• tool steels, which are extremely hard, and are used in cutting tools. They contain

tungsten and/or cobalt. A widely used grade of tool steel is high-speed steel,

which is used in cutting tools that operate at high temperatures, such as drill bits.

  One weakness of mild steel is that it corrodes - its surface progressively deteriorates due to a chemical reaction. This reaction takes place between the iron in the steel and the oxygen (02) in the air, to form iron oxide. When iron corrodes, we say that it rusts. In some metals, such as aluminum (Al), the presence of corrosion is not a problem, as the layer of oxide around the metal remains hard, which prevents it from oxidizing any further. However, when mild steel goes rusty, the rust on the surface comes off continuously, and a new rusty layer forms, progressively 'eating into' the metal.

 

5. Скажите, являются ли данные утверждения верными или неверными (true or false):

1 Steel is an alloy of iron and carbon.

2 Mild steel is a high carbon steel.

3 Alloy steels contain carbon.

4 Chromium and nickel are used as alloying metals in steel.

5 Low alloy steels contain more chromium than iron.

6 Stainless steel is an alloy steel.

7 Tungsten is added to steel to make it softer.

8 High-speed steel is suitable for making cutting tools that get very hot.

Text 3

 

1.Прочитайте слова по транскрипции:

duralumin |djʊˈraljʊmɪn|, titanium |tʌɪˈteɪnɪəm|, brass |brɑːs| , precious |ˈprɛʃəs|, galvanized |ˈɡælvənaɪzd|, zinc |zɪŋk|.

 

2.Обратите внимание на перевод следующих слов и словосочетаний:

aircraft manufacturing -    самолётостроение;

lightweight metal - лёгкий металл;

pipe - труба;

brass - жёлтая медь; латунь;

duralumin – дюралюминий;

tin - олово, жесть;

lead - свинец;

silver - серебро;

gold – золото;

corrosion-resistant - коррозиеустойчивый, устойчивый к воздействию коррозии;

plating - покрытие металлом (электролитическим путём);

galvanizing - гальваническое покрытие металлом; оцинковка;

molten - расплавленный; жидкий;

acid - кислота;

electrolyte - электролит;

negative terminal - отрицательная клемма, полюс аккумуляторной батареи;

positive terminal - полюс аккумуляторной батареи; положительная клемма.

 

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NON-FERROUS METALS

 Aluminium is widely used, often in alloy forms. An example is duralumin, an alloy used in aircraft manufacturing, which also contains copper ( 4.4%) and magnesium (1.5%). Aluminium can also be alloyed with titanium to produce very strong, lightweight metals.

  Copper is an excellent electrical conductor, which makes it ideal for use in electric wires. Good ductility also makes it suitable for pipes. Copper is widely used in alloys, notably brass (copper and zinc) and bronze (copper and tin, and sometimes lead).

  Silver is a precious metal - a reference to its high cost. It is a better electrical

conductor than any other material, so it is often used for electronic connections. Another precious metal - gold - is also an excellent conductor, and is highly corrosion-resistant.

 Non-ferrous metals can be used to protect steel from corrosion by plating it- that is, covering it with a thin layer of metal. An example is galvanizing (zinc plating).

   Steel can be hot-dip galvanized, by placing it in molten (liquid) zinc. It can also be electrogalvanized, which is a type of electroplating. With this technique, the steel component is placed in a liquid (often an acid)- called the electrolyte- and connected to the negative terminal (-) of an electrical supply, to become the cathode (the negative side). A piece of zinc is also placed in the electrolyte, and is connected to the positive terminal ( +) of the supply. This then becomes the anode (the positive side). An electric current then flows between the pieces of metal, through the electrolyte. This causes a chemical reaction, which deposits zinc

on the cathode, plating the component.

 A related process, called anodizing, is used to protect aluminium. The component to be anodized is connected to the positive terminal (to become the anode) and placed in an electrolyte, with a cathode. As electricity flows, aluminium oxide is deposited on the anode. As this is harder than aluminium metal, it provides protection.

 

5.Составьте предложения:

 

Duralium	can be mixed with copper to make	silver.
Titanium	resists corrosion better than the other precious metal,	brass.
Zinc	has a high strength-to-weight ratio and is often alloyed with	aluminium.
Copper	is an aluminium alloy that also contains copper and	bronze.
Gold	can be mixed with tin and lead to produce	magnesium.

 

Text 4

 

1.Прочитайте слова по транскрипции:

latex |ˈleɪtɛks|, polymer |ˈpɒlɪmə|, synthetic |sɪnˈθɛtɪk|, thermoplastic |θəːməʊˈplastɪk|.

 

2.Обратите внимание на перевод следующих слов и словосочетаний:

polymer - полимер;

rubber - резина; каучук;

natural polymer - натуральный полимер, природный полимер;

manmade - искусственный, созданный руками человека;

thermoplastic – термопластик;

mould - литейная форма;

solid material - монолитный материал, сплошной материал;

ABS - АБС-пластик;

polycarbonate - поликарбонат;

thermoset - отверждаемый материал;

epoxy resins - эпоксидные смолы;

polyimide - полимид;

engineering plastics - конструкционные пластики; конструкционные пластмассы;

elastomer - эластомер (вещество).

 

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POLYMERS

 With names such as polytetrafluoroethyline and polyethyleneteraphthalate, it's not surprising that polymers are usually called by their more common name, plastic. But what, exactly, is a polymer or a plastic?

 Polymers are compounds made up of several elements that are chemically bound. Most compounds consist of large numbers of tiny molecules, which each contain just a few atoms. For example, a water molecule - H20- contains two hydrogen atoms and one oxygen atom. But the molecules of polymers contain huge numbers of atoms, joined together in long chains.

 Rubber, thanks to its many uses from rubber bands to car tyres, is one of the best-known polymers. It comes from latex, a natural liquid which comes from rubber trees. Rubber is therefore a natural polymer. However, most of the polymers used in industry are not natural, but synthetic. The term 'plastic' is generally used to refer to synthetic polymers- in other words, those that are manmade.

 Synthetic polymers can be divided into two main categories:

 Thermoplastics can be melted by heat, and formed in shaped containers called moulds. After the liquid plastic has cooled, it sets to form a solid material. A thermoplastic is a type of plastic that can be heated and moulded numerous times. Examples of thermoplastics that are common in engineering include:

• ABS (acrylonitrile butadiene styrene)- stiff and light, used in vehicle bodywork

• polycarbonate - used to make strong, transparent panels and vehicle lights

• PVC (polyvinylchloride) -a cheaper plastic used for window frames and pipes.

 Thermosetting plastics, also called thermosets, can be heated and moulded like

thermoplastics. They may also be mixed from cold ingredients. However, during cooling or mixing, a chemical reaction occurs, causing thermosets to cure. This means they set permanently, and cannot be moulded again. If a thermoset is heated after curing, it will burn. Examples of thermosets used in engineering are:

• epoxy resins- used in very strong adhesives

• polyimides- strong and flexible, used as insulators in some electric cables.

 Two more categories of polymer are engineering plastics and elastomers. Engineering plastics are mostly thermoplastics that are especially strong, such as ABS and polycarbonate. Elastomers are very elastic polymers which can be stretched by force to at least twice their original length, and can then return to their original length when the force is removed.

 

5. Выберите нужное слово, чтобы закончить текст:

 

A lot of rubber is made from latex, a (1) natural/synthetic polymer which comes from rubber trees. However, not all rubber comes from trees. Synthetic rubber is a (2) manmade/natural polymer with similar properties to latex. Plastics are also polymers. Like rubber, they consist of long chains of (3) atoms/molecules which form extremely large (4) atoms/molecules.