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 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 p 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 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 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 + -ENto harden to strengthen EN + Noun to encircle to enjoy FROM ADJ to NOUN LATIN ORIGINENGLISH (LATIN) ORIGIN -ITYactivity-NESShardness - NCE(Y)importance-TH/HTtruth/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 GlassFeAlCuRubberPlastic Good-Bad conductor DCBADE Hard-softABCCED Heavy-lightCBDAEE More-less Malleable EC/B AD/E Tough-BrittleECBABD More-less Recyclable BDADCB

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 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.

STRUCTURES OF COMPARISON 39 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 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

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 The same Noun as identical TO X A is similar TO Xin (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 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 distinguishbetween 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 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.