UNIT 3 PROPERTIES OF MATERIALS - PowerPoint Presentation

UNIT 3PROPERTIES OF MATERIALSCOMPARISON & 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 33-34THERMOSETS : Shaped only once Rigid , can be broken , not soft en ed again TYPES: UF, MF Tough ness Electrical and thermal resista nce Scratch resistant Dark colours and cheaper -> PF

Thermoplastics p 33-34 - can be reshaped and can be soft en ed again TYPES : Polyethylene : cheap / tough / light Low dens ity : transparent / flexible High dens ity : rigid Polypropylene : resilient / less inclined to stress-cracking / not weak en ed by flexing / more costly ( expensive ) / brittle Polystyrene : cheap / light / rigid / brittle => tough en ed PVC : rigid & flexible / heavy Nylon : synthetic / tensile streng th / thermal resista nce PTFE : costly / resistant to chemicals & erosion / thermal resista nce / low friction

PROPERTIESElastic : 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 p34It 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 34It 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 strengthDuctile & malleableZINCA non-ferrous metallow hardness & Very corrosion resistantA relatively heavy metal, but lower density than cast iron, copper or leadrelatively high fusibility but lower than that of leadLEADHigh densityMelts very easilyLow tensile strengthALUMINIUMLow densityDuctile & malleableRelatively low tensile strength

WORD FORMATION p 36 FROM 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 efficiency

Word Formation (N/ADJ/VB) p 37COPPER-NICKEL ALLOYS   The attract IVE corrosion resist ANCE of copper-nickel alloys in sea water has led to their substanti AL use in marine services. They have good mechanic AL stren GTH 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

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 (-LY) are used: -ADV+ADJ = Aluminium is extremely light. -VERB+ADV= Cool the bar slowly. -ADV+ Past Participle= This alloy is highly recommended for propellersNOTE: ADJ & ADV = NO PLURAL

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 propellersNOTE: ADJE & ADV = NO PLURAL

Adj VS Adv p 38 1.- 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.

TABLE p 37 Glass 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- less Recyclable B D A D C B

COMPARISON: spelling p 39 Bigger Deeper Nearer Slower Taller F arther Shorter Fatter Heavier Wider Hotter Greater

STRUCTURES OF COMPARISON 39 QUANTITY : - UNCOUNTABLE => A large/small AMOUNT of + N // MUCH- LITTLE - COUNTABLE => A large/small NUMBER of + N // MANY- FEWThere is AS MUCH water AS we thought – uncountable TANTO COMOThere are AS MANY people AS we thought–countable TANTOS COMOSO + Adj/SO MUCH(MANY) that + SENTENCE TAN(TO/S) QUETOO +ADJ => TOO BIG/TOO MUCH+N money /TOO MANY+N products. DEMASIADO(S)MUCH MORE/LESS MUCHO MAS/MENOS(much stronger/much less hard)This box is THE SAME size AS that one.This box is TWICE larger THAN /HALF AS large AS/ EL DOBLE DEThis box is TWICE THE SIZE of the other box.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 As copper has become RARER and MORE EXPENSIVE , aluminium has come into use even though it has a HIGHER resistance THAN copper. In early days, people thought that the electric current flowed in THE SAME way AS waterIn 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.If we let the bar cool FASTER than before, we obtain a metal which is HARDER and MORE EASILY machineable.Hydrogen is one of THE LIGHTEST elements while uranium is one of THE HEAVIEST.Electrons orbiting FARTHER from the nucleus are those which are MORE EASILY drawn away.In generators, THE FASTER the wires move, THE GREATER the generation of emf.Thermoplastics can be reheated AS MANY times AS required. MOST (OF THE) metals are alloyed to get better properties.Oil is THE MOST WIDELY USED energy sourceIf the layer is TOO thin it will not protect the metal below 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 : This is A FERROUS metal, containing 3%CarbonIt is very HARD but BRITTLE, It will NOT BENDUSES: bodies of machine tools, vices, etcSpring STEEL: A very TOUGH metal USES: As its name suggests, it is mostly used for making springs, e.g. for CLOCKS. It will also be found in a car ENGINE as the material for piston ringsMild STEEL: It has MUCH LESS CARBON than cast IRON, As a result, it is SOFTER but not BRITTLE, It is very TOUGH and can be worked into different SHAPES USES: Girders in bridges , car bodywork , nuts and bolts are all made from mild steel

LISTENING (6 metals) p 40 ALUMINIUM : This PURE or base METAL is the world’s most common metalIs is very LIGHT & RESISTANT TO CORROSION; THOUGH SOFT & easily SHAPED, it is NEVERTHELESS very STRONG. USES: used for making pots & pans, foil and the PISTONS in CAR ENGINE.COPPER: It is easily BENT & STRETCHED; It is a very GOOD CONDUCTOR of HEAT & ELECTRICITY.USES : ELECTRICAL WIRING, water PIPES and car radiatiors are common usesZINC: a PURE METAL, highly RESISTANT TO CORROSION, It is easily CAST, and so can be used for making fairly COMPLEX SHAPES, such as carburettors

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 42As ADJ as X The same Noun as identical TO X A is similar TO X in (that) like XA resembles XA, like X, is a (gas)A and X have their elasticity in commonSimilarly (to X), In the same way (as), In this way

DIFFERENCES p 42COMPARATIVES A differs FROM X in (that) A is different FROM X in (that) The differences between A and X are... differentiateWe can distinguish between A and X make a distinction tell the differenceA can be distinguished FROM X by....(its shape) unlike X,A, as opposed TO X, in contrast TO X, A DIFERENCIA DE as distinct FROM X,

DIFFERENCES p 42 CONJUNCTION + SENTENCE (Subject + VB) ON (the) one hand .........., ON the other ( hand )....... But / although = though (even though)/ whereas / whileHowever/ /nevertheless/ yet sin embargo, no obstanteOtherwise (=if not) o si no .... De lo contrarioON the contrary/Contrarily(TO this/the examples given…) / BY/IN contrast(TO this/the examples given) Por el contrarioPREPOSITION ( + NOUN/ -ING VB)Instead (of)/ rather (than) en vez de…, / en su lugarIn spite of /Despite +NOUN/ VB-ING = a pesar deIn spite of /Despite the fact that + SENTENCE (= although) 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.