UNIT 3
PROPERTIES 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 p 33-34
• THERMOSETS:
– Shaped only once
– Rigid, can be broken, not softened again
– TYPES: UF, MF
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•
•
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Toughness
Electrical and thermal resistance
Scratch resistant
Dark colours and cheaper -> PF
Thermoplastics p 33-34
• - 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 / more costly (expensive) / brittle
- Polystyrene: cheap / light / rigid / brittle => toughened
- PVC: rigid & flexible / heavy
- Nylon: synthetic / tensile strength / thermal resistance
- PTFE: costly/ resistant to chemicals & erosion /thermal
resistance / low friction
PROPERTIES
• Elastic: The tendency of a material to regain its original
dimensions (size and shape) upon the removal of load or
force.
• Plastic: The tendency of a material to permanently deform
when subjected to external load beyond the elastic limit.
• Tough: The ability of a material to absorb energy in plastic
deformation up to the point of fracture.
• Resilient: The ability of a material to absorb energy under
elastic deformation and to recover this energy upon removal
of load.
• Ductile: The ability of a material to be drawn into wires
• Malleable: The ability of a material to be formed into sheets
by hammering or rolling.
• Brittle: It is the tendency of a material to crack when it is
subjected to deformation..
• Hard: The resistance offered by a material to indentation or
scratching.
PROPERTIES – Matching p34
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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 p 34
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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 p35
• 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 FORMATION p 36
FROM ADJ/ Noun to VERB
ADJ/ Noun + -EN
EN + Noun
to harden
to strengthen
to encircle
to enjoy
FROM ADJ to NOUN
LATIN ORIGIN
ENGLISH (LATIN) ORIGIN
-ITY
activity
-NESS
hardness
-NCE(Y) importance
-TH/HT
truth/height
Word Formation (N/ADJ/VB) p 37
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
TABLE p 37
Glass
Fe
Al
Cu
Good-Bad
conductor
Hard-soft
D
C
B
A
D
E
A
B
C
C
E
D
Heavy-light
C
B
D
A
E
E
More-less
Malleable
Tough-Brittle
E
A
D/E
E
C
B
A
B
D
More-less
Recyclable
B
D
A
D
C
B
C/B C/B
Rubber Plastic
ADVERBS & ADJECTIVES p38
• 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 Adv p 38
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 material
10.- Protons are positively charged particles.
1.-
STRUCTURES OF COMPARISON 39
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QUANTITY: small/large AMOUNTS (uncount)/ NUMBERS (count) OF
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 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: Comparison p 39
1. 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 water
3. 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 source
11. If the layer is TOO thin it will not protect the metal below
12. We spend SO MUCH energy in producing electricity that we should
concentrate our efforts on other possibilities to generate it
LISTENING (6 metals) p 40
• 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) p 40
• 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
LISTENING
METAL
cast IRON
spring STEEL
mild STEEL
ALUMINIUM
COPPER
ZINC
PROPERTIES
-FERROUS metal
contains 3% CARBON
very HARD but brittle
it will not BEND
- tough
it has LESS CARBON than
cast iron
SOFTER but not brittle
- tough
can be worked into SHAPES
-base or pure metal
LIGHT and RESISTANT to
CORROSION
though SOFT and easily
shaped it is very STRONG
easily BENT and stretched
GOOD CONDUCTOR of
HEAT
and ELECTRICITY
- a pure metal
RESISTANT to
CORROSION
- easily cast
making complex SHAPES
USES
- bodies of machine tools
- vices
SPRINGS (clocks)
car .ENGINE (piston rings)
- girders in bridges
- car bodywork
- nuts and bolts
- pots and pans
- foil
PISTONS in CAR
ENGINE
electrical WIRING
water PIPES
car RADIATORS
- carburettors
COMPARISON AND CONTRAST 42
• 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 p 42
• As ADJ as X
• A is
identical TO X
similar TO X
like X
The same Noun as
in (that)
• 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
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DIFFERENCES p 42
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
•
as opposed TO X,
A DIFERENCIA DE,
DIFFERENCES p 42
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: Comparison&constrast p 43
• 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.