UNIT 3PROPERTIES OF MATERIALS

COMPARISON & CONTRAST

Vocabulary • Properties of Materials (Adj / Nouns / Vbs)• WORD FORMATION: N/VB from ADJ

Grammar and functions• Comparison: special structures• ADJ vs ADV• Comparing & Contrasting: connectors

READING

• THERMOSETS:– Shaped only once– Rigid, can be broken, not softened again– TYPES: UF, MF

• Toughness• Electrical and thermal resistance• Scratch resistant• Dark colours and cheaper -> PF

thermoplastics

• - can be reshaped and can be softened again• TYPES:

– Polyethylene: cheap / tough / light• Low density: transparent / flexible• High density: rigid

- Polypropylene: resilient / less inclined to stress-cracking / not weakened by flexing / expensive / brittle

- Polystyrene: cheap / light / rigid / brittle- PVC: rigid & flexible / heavy- Nylon: tensile strength / thermal resistance- PTFE:costly/ resistant to chemicals & erosion /thermal

resistance / low friction

PROPERTIES - Matching

• It is hard but fractures easily when hit or worked BRITTLE• It bends easily without breaking FLEXIBLE• It has a high mass HEAVY• It is easy to scratch SOFT• It cannot be dented or scratched HARD• It retains its new shape when force is applied, as opposed to elastic

materials. PLASTIC• It can be drawn or stretched into coils DUCTILE• It is able to withstand a stretching load without breaking TENSILE

STRENGTH• It produces friction when rubbed ROUGH• It returns to its original shape when the deforming force is removed

ELASTIC

PROPERTIES - Matching

• It has a low density LIGHT• It is able to resist an impact load without breaking TOUGH• It is difficult to bend RIGID/STIFF• It burns easily COMBUSTIBLE• You can see through it TRANSPARENT• It can be hammered into a shape MALLEABLE• It produces little friction SMOOTH• It does not rust CORROSION RESISTANT• It allows the flow of electricity GOOD CONDUCTOR• It dissolves in water SOLUBLE

PROPERTIES OF 4 MATERIALS• COPPER

– A non-ferrous metal– high electrical and thermal conductivity– high tensile strength– Ductile & malleable

• ZINC– A non-ferrous metal– low hardness & Very corrosion resistant– A relatively heavy metal, but lower density than cast iron, copper or

lead– relatively high fusibility but lower than that of lead

• LEAD– High density– Melts very easily– Low tensile strength

• ALUMINIUM– Low density– Ductile & malleable– Relatively low tensile strength

WORD FORMATIONFROM ADJ/ Noun to VERB

ADJ/ Noun + -EN to harden

to strengthen

EN + Noun to encircle

to enjoy

FROM ADJ to NOUNLATIN ORIGIN ENGLISH (LATIN) ORIGIN

-ITY activity -NESS hardness

-NCE(Y)importance -TH/HT truth/height

Word Formation (N/ADJ/VB)COPPER-NICKEL ALLOYS

•  The attractIVE corrosion resistANCE of copper-nickel alloys in sea water has led to their substantiAL use in marine services.

• They have good mechanicAL strenGTH and ductiLITY but cannot be hardENED by heat treatment.

• Of particulAR interest is their thermAL conductivITY this explains their popularITY for heat exchangers, where higher strenGTH is not the most importANT factor.

• They are also non-magneTIC and have a magneTIC permeabILITY close to uniTY

TABLEGlass Fe Al Cu Rubber Plastic

Good-Bad conductor

D C B A D E

Hard-soft A B C C E D

Heavy-light C B D A E E

More-less Malleable

E C/B C/B A D/E

Tough-Brittle E C B A B D

More-lessRecyclable

B D A D C B

ADVERBS & ADJECTIVES

• ADJECTIVES are used:-BE(BECOME)+ADJ=This metal is weak / it is important.-ADJ + NOUN =a weak metal.-MAKE + OBJECT + ADJ = this method makes the metal hard.

• ADVERBS are used:-ADV+ADJ = Aluminium is extremely light.-VERB+ADV= Cool the bar slowly.-ADV+ Past Participle= This alloy is highly recommended for propellers.

Adj VS Adv1.- Such a concentration of lead is highly dangerous for

men.2.- Hard steel is generally preferred when building huge

bridges.3.- Magnesium is known as a metal which burns easily. 4.- The cable is to be covered by a thin rubber coating.5.- Stainless steel consists of slightly high proportions of

chromium.6.- If you put a pipe here, it should not be easily bent./7.- This alloy performs well due to its exceptional

electrical conductivity.8.- Researchers found extremely rare compounds on

Mars.9.- Chalk is a good example of a soft material10.- Protons are positively charged particles.

STRUCTURES OF COMPARISON• There is AS MUCH water AS we thought – uncountable TANTO COMO• There are AS MANY people AS we thought.–countable TANTOS COMO• It is SO GOOD/SO MUCH(MANY) that + SENTENCE TAN(TO/S) QUE• TOO +ADJ => TOO BIG / TOO MUCH money /TOO MANY products.

DEMASIADO(S)• This box is THE SAME size AS that one.• This box is TWICE larger THAN /HALF AS large AS/ EL DOBLE DE• This box is TWICE THE SIZE of the other box.• Technology is becoming MORE AND MORE sophisticated.• MOST (OF THE) METALS are good conductors.• The most/very WIDELY/COMMONLY/FREQUENTLY USED metals are

steel and copper. (SE USA MUCHO/ ES EL MAS USADO)• THE GREATER the amount of carbon added, THE LESS SOFT the

steel becomes (cuanto mayor/menor… mayor/menor).• This car is QUICKER (Adj). This car runs MORE QUICKLY (Adv)• THE FORMER … THE LATTER (El primero ….. El último)

EXCERCISE: Comparison1. As copper has become RARER and MORE EXPENSIVE, aluminium has

come into use even though it has a HIGHER resistance THAN copper.2. In early days, people thought that the electric current flowed in THE SAME

way AS water3. In Volta's cell, one of the metals is chemically MORE ACTIVE THAN the

other and gives off electrons which are attracted by THE LESS ACTIVE metal.

4. If we let the bar cool FASTER than before, we obtain a metal which is HARDER and MORE EASILY machineable.

5. Hydrogen is one of THE LIGHTEST elements while uranium is one of THE HEAVIEST.

6. Electrons orbiting FARTHER from the nucleus are those which are MORE EASILY drawn away.

7. In generators, THE FASTER the wires move, THE GREATER the generation of emf.

8. Thermoplastics can be reheated AS MANY times AS required.9. MOST (OF THE) metals are alloyed to get better properties.10.Oil is THE MOST WIDELY USED energy source11. If the layer is TOO thin it will not protect the metal below12. We spend SO MUCH energy in producing electricity that we should

concentrate our efforts on other possibilities to generate it

LISTENING (6 metals)

• Cast IRON: FERROUS metal, 3%C, HARD but BRITTLE, will not BEND

• Spring STEEL: TOUGH. Uses: springs, e.g. in CLOCKS, car ENGINE :piston rings

• Mild STEEL: MUCH LESS CARBON than cast IRON, SOFTER but not BRITTLE, though very TOUGH can be worked into different SHAPES

LISTENING (6 metals)

• ALUMINIUM: base or PURE METAL, LIGHT & RESISTANT TO CORROSION; THOUGH SOFT & easily SHAPED, NEVERTHELESS very STRONG. Uses: PISTONS in CAR ENGINE.

• COPPER: easily BENT & STRETCHED; GOOD CONDUCTOR of HEAT & ELECTRICITY. Uses: ELECTRICAL WIRING, water PIPES

• ZINC: a PURE METAL, RESISTANT TO CORROSION, easily CAST, used for making COMPLEX SHAPES

COMPARISON AND CONTRAST• We compare X with/to Y

• X, in comparison with/to Y, has advantages over other elements– as regards (size)

– regarding (size)

– with regard to (size)

– with respect to (size)

–as far as (size) is concerned

SIMILARITIES• As ADJ as X The same Noun as

identical TO X• A is similar TO X in (that)

like X

• A resembles X

• A, like X, is a (gas)• A and X have their elasticity in common

• Similarly (to X), In the same way (as), In this way

DIFFERENCES• COMPARATIVES• A differs FROM X in (that)• A is different FROM X in (that)• The differences between A and X are...•

differentiate• We can distinguish between A and X• make a distinction• tell the difference• A can be distinguished FROM X by....(its shape)•

unlike X,• A, as distinct FROM X,• in contrast TO X A DIFERENCIA DE,• as opposed TO X,

DIFFERENCES

CONJUNCTION + SENTENCE (Subject + VB)•ON (the) one hand.........., ON the other (hand).......

•But / although = though(even though)/ whereas / while

•However/ /nevertheless/ yet sin embargo, no obstante

•Otherwise (=if not) o si no .... De lo contrario

•ON the contrary/Contrarily(TO this/the examples given…) / BY/IN contrast(TO this/the examples given) Por el contrario

PREPOSITION ( + NOUN/ -ING VB)

•Instead (of)/ rather (than) en vez de…, / en su lugar

•In spite of /Despite +NOUN/ VB-ING = a pesar de•In spite of /Despite the fact that +SENTENCE a pesar de que

IN SPITE OF/DESPITE its low density/ THE FACT THAT it is light …

EXERCISE: expressions• If we...COMPARE.. wrought iron and cast iron, we may find

some...SIMILARITIES.. • Both of them are ..SIMILAR IN THAT....they contain iron;

wrought iron, . LIKE/IN THE SAME WAY AS/SIMILARLY TO cast iron,

• HOWEVER..., .ALTHOUGH they are very....SIMILAR IN .... their composition, we may notice some ...DIFFERENCES... REGARDING/WITH RESPECT TO/ AS REGARDS their properties;

• thus ,wrought iron is very malleable, WHEREAS/WHILE cast iron is THE LEAST MALLEABLE of all ferrous metals

• .. ON THE OTHER HAND, cast iron ...DIFFERS FROM wrought iron in elasticity because WHEREAS/WHILE the former has a very poor elasticity, the latter is very elastic.

• The..DIFFERENCE between these two metals comes from the different amount of carbon content: THE HIGHER the content of carbon, THE LESS MALLEABLE AND ELASTIC these metals are.