8/10/2019 Material Science Cheatsheet for Midterm New

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Used to produce containers, light bulbs through pressing,drawing, or blow moulding; A gob of molten glass i sperformed into a crude shape (a parison) then pressed orblown into a final shape; Annealing Range: Glass ma beannealed then slowl coo!ed to reduce residual stressTempered Glass "roduced b #uenching the surface with air;$urface contracts #uic!l while centre contracts more slowl;%ifferential cooling causes compressi&e stresses to de&elopon the surface with tensile stresses in the centre; 'mpro&estensile strength and impact propertiesLaminated Glass onsists of two annealed glass pieceslaminated with a polmer (pol&inl butral) in bw; Used toma!e windshields; *ulletproof glass is made withpolcarbonate laers insteadGlass Cer amics +igh crstalline materials made fromamorphous glasses;; +eat treatment after forming and addedoides allow for crstalli-ation; .ffers good mechanicalstrength, toughness, high temperature corrosion resistance,with a low coefficient of thermal epansion;Chapter 16; PolymerPolymeris a long chain of molecules made from manmonomers bonded together; /picall polmers consist of acarbon bac!bone which is co&alentl bonded to other atomssuch as hdrogen ogen or nitr ogen

3 Types of PolymersThermoplastics; Atoms within the chains are co&alentlbonded with the chains themsel&es bonded b &an der 0 aalsbonds; Are generall ductile; 1a be amorphous or crstallinedepending on the temperature; $often when heated whichallows for shaping and eas recclingThermosettingAlso long chain molecules; $trongl cross2lin!ed forming rigid 3% structures; $tronger but more brittlethan thermoplastics; %o not melt 4 simpl decompose;Reccling difficultElastomers apable of elastic deformation greater than5667; 1a be both a thermoplastic or thermosetting; ontaincoil2li!e molecules that stretchTypes of Polymerization ( types!"ddition Polymerization (Chain Gro#th!Under heatpressurecatalsts double bonds within amonomer molecule are bro!en to form a single bond; 8nds ofsingle bond can now bond with other monomers to form longerchains; $maller chains ma bond together (combination),hdrogen atoms bond with one end (creating a double bond2 called disproportionation) or terminators can be addedCondensation Polymerization ($tep%Gro#th!/wo or more molecules combine to form a polmer and asmall molecule b product (water, methanol, ethanol); 9engthof chain depends on the abilit of the reacting molecules toreach the ends of polmer chain; "rocess continues until no

more monomers a&ailable&egree of PolymerizationA&erage length of a linear polmer chain is gi&en b degree ofpolmeri-ation&egree of Polymerization '

Average molecular weight o

Molecular weight of repe'f polmer contains more than one monomer; the molecularweight of the repeat unit is the sum of the molecular weights ofthe monomers minus the molecular weight of the b2producteight ")erage *olec+lar eight: *'fi1i;10is theweight a&erage molecular weightfiis the weight fraction of the polmer ha&ing chains within thatrange; 1iis the mean molecular weight of the chains within arange,+m-er ")erage *olec+lar eight: *n'i1i; 1nis thenumber a&erage molecular weight; iis the number fraction ofchains within that range ; 1iis the mean molecular weight ofthe chains within a range

/he number a&erage molecular weight is alwas smaller than

the weight fraction molecular weight*echanical Properties of Thermoplastics.iscoelastic: 1acause polmer to be translucent

Copper "lloys 8cellent electrical and thermal conductors;

Good corrosion C wear resistance; Good strength, high ductilit,

cold wor!abilit

Common Copper "lloys *rass (u D En) 4 Good strength,

ductilit, corrosion resistance; *ron-e (u D $n) 4 Good strength

and wear resistance; u D *e allos 4 +ighest strength of u

allos 4 age hardenable

*agnesi+m "lloys 9ow densit, melting temp, and modulus of

elasticit; Good specific strength, corrosion resistance (ecept

marine en&ironments); "oor fatigue, creep, and wear resistance

,icel "lloys +a&e good strength, particularl at high temp;

Good corrosion resistance; Used for heat echangers, gas

turbines

Titani+m "lloys +igh strength, low densit; 8cellent corrosion

resistance; Good high temperature properties; Used in chemical

processing e#uipment, biomedical implants, Fet engines

Chapter 150 Ceramicseramics: solid compounds that comprise at least one metaland one non2metallic element or a combination of at least twonon2metallic element solids>Propert ies of Ceramics +ard and wear resistant, brittle, prone

to thermal shoc!, refractor (high melting point), generallelectricall insulating, generall thermall insulating, generallnon2magnetic, chemicall stable and oidation2resistantProcessing of ceramics: > $nthesis of ceramic powders 5>*lending and spra dring using additi&es 3> $haping into usefulshapes called green ceramics H> onsolidation into a denseobFect using sintering or firing I> $econdar processing such ascutting or polishing J>Kinal sintered ceramic product>$haping methods0niaial p ressing : ma!es simple, small parts> "owder iscompacted in a die ca&it to gi&e moderate strength andincrease part densit$lip casting0 > Kill "aris mould with slip 5> 1ould etracts li#uidand forms compact along mould walls 3> 8cess slip is drainedH> asting is remo&ed after partial dringTape casting: "roduces thin ceramic tapes, alumina electronicpac!ages, barium titanate capacitors> $lurrmiture i s pouredinto a doctor blade, which controls i ts thic!ness as it is cast ontoa substrate (polmer sheet or stainless steel)>Etr+sion process0 > *lending 5> 8trusion2 pushed through adie ca&it through pressure to get the desired 3> utting anddring 2 after desired length is etruded, green part is cut anddried before sintering7n8ection *o+lding0 > *lending and compounding 5> 1oulding2 pressed into cold die ca&it with a plunger or screw mechanism3> 8Fection and binder remo&al 2 after the part is remo&ed fromthe mould, the binder is remo&ed b heat treatment

Cold 7sostatic Pressing (C7P!0 useful for comple shapes>"owder is placed inside a mould and pressed in all directions inpressure &essel to compress into a useful shape, high pressedgreen densities$intering of Ceramics: to reduce surface area in green bod> After pressing to form a green bod, particles are in contactwith each other forming nec!s 5> Grain boundar forms in eachnec! (bc crstallographic orientation is different in each particle)3> As sintering progresses, spaces bw particles become poresand !eep on shrin!ingPress+re "ssisted $intering(old) +ot pressing

Uniaial pressure applied before sintering (cold)

Uniaial pressure applied during sintering (hot)

(old) +ot 'sostatic "ressing (+'")

+igh gas pressure (266 1"A) applied in all directions to assist

compacting the green bod (before and after sintering)

Ar tpicall used to pre&ent reacting with material (argon)

$intered Ceramics /he goal of green forming and sintering isto reduce the porosit as much as possible; "ores can be interconnected or isolated depending on the amount of sintering;'nterconnected pores allow for filtering but are structurall wea!Porosity "ores are flows that reduce the tensile strength ofceramics; $ome porosit can be helpful for thermal shoc! butgenerall should be a&oided

Apparent Porosity@ WwWdWwWs

x100

Ww=Weight of ceramic afterWd=Dry weight of ceramic ;

Ws=Weight of ceramic when

True Porosity@p !

p x 100 ;

p=theoretical density of the cdensity of the ceramic

Glas ses =on2crstalline, i>e> short2range order of molecules butno long2range order; Usuall based on $io5; 1ost properties aresimilar to those of ceramics; Glasses are metastable and willcrstalli-e gi&en the right combination of circumstances>

Exceptions: 1ost cannot be used to at &er high temperatures;Glass 9ormat ion pon Cooling Kor crstalline materials, whena li#uid is cooled below the metling temperature, a solid formsha&ing a higher densit; A li#uid ma be cooled below themelting temperature becoming an undercooled li#uid; if coolingis sufficientl fast, crstals of solid will not form and li#uidremains undercooled; *elow the glass2transition temperature,the li#uid solidifies with an amorphous structure forming a glass;/he glass2transition temperature is noted b the reduced rate ofdensit change with decreasing temperatureClassification of Glass :idesGlass 9ormers: /hese oides are capable of forming glass>7ntermediates: .ides that ma be incorporated into the glassstructure but do not form glasses on their own>*odifiers: .ides that brea! up the networ! structure and allowthe glass to crstalli-e; Reduce melting point and &iscosit of$i.5ma!ing it easier to form glasses at lower temperatures>Types of Glasses$oda Lime Glass2 reduces melting temperature, reduces watersolubilit; /orosilicate Glass2 "ossess ecellent chemical anddimensional stabilit, used for lab ware, containers for nuclearwaste> Calci+m "l+mino-orosilicate Glass2 used for glassfibres in fibreglass and composites> *agnesi+m"l+minosilicate Glass2 used for glass fibres in high strengthcomposites 9+sed $ilica2 *est resistance to high temperature,thermal shoc!, and chemical r esistanceGlass Pro cessing +eating the glass to high temperatures

changes the &iscosit of the glass and gi&es differentcharacteristics; Li+id 2ange: Glass is molten and used toproduce glass sheet; 1irrors and fibres are produced in thisstate;oring 2ange: Glass is heated so it is formable but not

Crystallization"olmer ma crstalli-e to i mpro&e: %enResistance to chemical attac!, 1echanical properties> 1apolmer to be translucentCopolymers opolmers are polmers made of differenmolecules within a chain; reated to blend properties of dpolmersTemperat+re Effects1echanical properties of thermoplastics change with tem< Thermoplastic $tatesLiquid: /hermoplastics abo&e melting temperature> *onbetween chains are wea!; chains mo&e easil; no strengelasticit: ubbery: /hermoplastics Fust below meltingtemperature Fust below melting temperature; chains mo&eresulting in plastic deformation (state used for forming); LAt lower temperature(Lust abo&e glass transition temp); between chains strengthen; "olmer is stronger and mor!lassy "igid State#: "olmer structure becomes rigid (li!e); $trength and stiffness impro&e but polmer becomeCrystallinity in Polymers0 /hermoplastics ma partiallcrstalli-e at temperatures blow melting point; hains beclosel aligned folding o&er themsel&es creating plates (l

7 rstalline @

" c(""a)

"(" c"a), p is the

of densit of the polmer, pais the densit of amorphous "cis the densit of completel crstalli-ed polmer*echanical Properties of Polymers1olecular weight, Amount of branching, %egree of branc%egree of cross2lin!ing, %egree of crstallinit (folding of /acticit, /emperature, $train rateGeometric 7somers0 1onomers with the same compositdifferent structures (ie rubber)Cross%lining: *onding between polmer chains to pre&&iscous plastic deformation (9ow cross2lin!ing 2 soft, flerubber bands, rubber glo&es)+igh cross2lin!ing 2 hard rigid (i >e> hoc!e puc!s)).+lcanization: /echni#ue for cross2lin!ing elastomer chaadding sulphur atom chains which displace hdrogen atoreferable, canMt reccle)Tensile Testing of Elastomers0All deformation is elastilinear); 'nitiall the polmer chains uncoil; hains then stfurther deformation; 8&entuall the bonds brea!Thermoplastic Elastomers %onMt rel on cross lin!ing fdeformation 2 instead one chain crstalli-es to pre&ent thof chainsThermosetting Polymers+ighl cross lin!ed; 9imited chain mo&ement due to 3% sGood strength stiffness and hardness, but brittle; *egin a

chains2mied with resins and heat to from cross2lin!ingCommon Thermosets "henolics 2 adhesi&es, bra!e paAmines 4 coo!ware; Urethanes 4 mattresses; "olestershulls; 8poies 2 Adhesi&ePolymer Processing+eated to near its melting point so its temperature is rubbli#uid> /hen formed in a die or mild and cooled >Thermoplastic 9orming Processes (&ifferent Process8trusion, *low moulding, 'nFection moulding, /hermoforalendaring, $pinning, astingEtr+sion +igh &olume plastic pellets pushed through a into a turning screw; /he screw creates friction N heat (O6from friction) D heaters melts the polmers; "ushed throudie; ooled (often through water); 1ost common method7n8ection *o+lding $imilar to etrusion ecept the molteis inFected into a complicated mould; 1ould consists of twsections that press the plastic together while i t is inFected/lo# *o+lding Used for hollow parts of all si-es; /ube oplastic is etruded into an open mould; Air pressure it useout the centre of the mould pressing the plastic into the m.ften used for bottlesThermoset "lace solid materials in the mould then heaticauses cross lin!ing to form the f inal product; ompressmoulding 2 high pressure and temperature causes the plamelt and it fills the mould as it coolshapter 5Compression mo+lding2 high pressure C temperature the plastic to melt C it fills the mould as it coolsof properties, strength, toughness, electrical conducti&itbone, teeth natural *etal matri composites (**Cs! Pmatri composites (P*Cs! ceramic matri composite(C*Cs!"ppcemented carbides i>e> cutting tools" -ras i)es i>e> grinding cutting toolsElectrical Contacts switches, relas> Ag20 composites resistance Ag: conducti&itP olymers fillers added to polmers2+le of *it+respredicts composite properties densitycomp ' )ol+me fraction= density fraction9i-re%reinforced Compositesstronger, fatigue resistancelasticit, stiff, brittle, metal, glass, or polmers, carbon, bmatri is softer, more ductile, eamples Qe&lar, tennis rac2+le of mit+respredicts densit (abo&e) C modulus of for loads to fibres Ec' ffEf >fmEm9oad perpen to fibresame, strain different)1?Ec 'fm?Em>ff?Ef9i-re Lengthdetermines load carring abilit, large aspestronger, smaller d@less flaws, longer fi&ers stronger bc esupport load, fibre &olume @ strong t oohiserssimple crstal fibres 2 strong*atriessupport fibres and !eep them i n proper positionpre&ents damage of fibres and crac!s in material controlelectrical, chemical C thermal properties of compositesPolymer @ *etal *atrigood bonding, allow transfer of

fibres, coefficients of thermal epansion similar throughoCeramicwea! bond between fibres and matri, deflect cma!e less brittle/onding @ 9ail+re Good bonding between matri C fibretransfer of stress coating i mpro&es bonding9i-re Prod+ction1etallic, glass C most composites fibrfrom the drawing process> carbon, *oron, C ceramics prothrough chemical &apor deposition Kibres, twisted to formbundled to form towsComposite prod+ction$hort fibre, casting or inFection mcontinuous handlaup*etal *atri Composites$trengthened b metal or cerafibres, good high temp properties i>e> AluminumCeramic *atri Compositeseramic fibres in a ceramistrong, fracture resistance,poor bonding between fibres amatricesCar-on Car-on Composite$uper strongLaminar Compositescoatings which impro&e corrosionresistanceAA to lamellae properties&ensity@ Sc @ TSifi *od+l+elasticity@ 8c @ Tfi8iPerpen to lamellae*od+l+s of elasticity@ 8c@ Tfi8B Crystal $ystems4 ubic, /etragonal, .rthorhombic,

Rhombohedral, +eagonal, 1onoclinic, /riclinic> ,+m-e

"toms per nit Cell4 orners @ O atom, Kace2entre

atom, *od2etnres @ atom> $imple ubic $tructure ($

atom> *od entered ubic $tructure (*) @ 5 atoms> entered ubic $tructure @ H atoms> All ha&e O corner at

stac!ing of the atoms within the crstal structure determi

si-e of the unit cell> Coordination ,+m-er4 +igher num

hapter 60 *echanical Properties

train2 measure of the amount of elongation per unit length

lastic Limit2 $tress where plastic deformation begins

roportional Limit4 1agnitude of stress where stress2strain

elationship is no longer linear> %eformation of a material is a

ombination of both proportional and elastic limit

ield $trength4 $hift strain (6>665) or (6>57)

od+l+s of 2esilience, 8r: 's the elastic energ absorbed

uring loading and subse#uentl released when the load is

emo&ed

igher Elastic *od+l+sindicates higher stiffness, steeper

ope

ensile To+ghness0 Represents the energ absorbed b a

material prior to fracture (Area under the true stress2strain

ur&e) (+igher strength @ higher energ absorption)

rittle *aterials0 8perience more stress than more ductile

materials8perience &er little plastic deformationGlasses and

eramics, the ield strength, tensile strength and fracture

trength are all the same> /ested through the bend test

ardness of *aterials 1easure of the resistance to plastic

eformation

hapter 0 "tomic $tr+ct+reonds: ('onic, co&alent, metallic and eramics and "olmers; *etallic:

ro&ides good electrical conducti&it, good ductilit, and high

melting temperatures; .an der aals: 'mportant in polmers as

e determine strength and ductilit

nteratomic $pacing: $pacing bw atoms is dependent on the

ttracti&e and repulsi&e forces> /he e#uilibrium interatomic

pacing occurs when the net forces acting on the atom is -ero>

picall e#ual to the atomic diameter>

hapter 130 $teels and Cast 7ronast 7ron arbon content N 5>7 arbon; melt at lower

emperatures (better for casting); contain graphite (form of purearbon); used for engine bloc!s, gears, pistonsteel arbon content V >H7; "lain carbon steels: =o alloingements added for strength; &er good general properties

strength, ductilit, weldabilit, machinabilit); &er poororrosion resistanceypes of Car-on $teels 9ow arbon steels (V6>37 ) 2 highest tonnage of steelroduced; 5> 1edium arbon steels (6>326>J7 ) 2 railwaac!s, gears, cran!shafts; 3> +igh arbon $teels (6>J2>H7) 2utting edges, dies, punchesote: /he more carbon the harder and stronger it is but the less

eldabilit and formabilit it has>lassification of $teels % "7$7?$"E (=ot used for stainlessteels or tool steels) consists of H digit number; first digit:dicates allo steel ( 4 plain carbon steel, H6 @ 1o steel, 4 r 4 1o steel, I 4 1o steel, I6 4 r steel); secondgit: indicates a modification;last two digits i ndicate 7 inundredths of a 7ool $teels high carbon with addition of alloing elements forgh hardenabilit and carbide formation; high hardness, wear

esistance, shoc! and impact resistance, and ele&atedemperature ser&ice (.btained through heat treating); used tout, machine, hotcold form or mould metals, polmers, anderamicslassification based on #uenching method, application method,r composition:

0 2 water hardening (inepensi&e); $ 2 shoc! resisting (impact); 2 oil hardening cold wor! steels (dies, punches); A 2 airardening cold wor! steels (dies, punches); % 2 high carbon,gh chromium, cold wor! steels (dies, punches); + 2 hot wor!teels; 1 2 1ohigh speed steels (cutting tools); / 4 0ungsten) high speed steels (cutting tools)tainless $teelsAllos of iron and chromium; ecellentorrosion and high temperature oidation resistancei&e tpes: 9erritic2 less epensi&e, used for construction, lac!uctilit and weldabilit, used for automoti&e ehaust,shwashers, decorati&e> *artensitic2 selected for cutting

dges with good wear and corrosion resistance, highemperatures will cause embrittlement> "+stenitic2 not heateatable, strain hardenable, strengthened b cold wor!ing,cellent corrosion resistance and formabilit, used forppliances, !itchen sin!s> &+ple2 combination of austeniticnd ferritic stainless steels with properties between each tpe>recipitation Dardened2 high strength and corrosionidation resistanceast 7ron Ke22$i allos; ecellent casting, good wearorrosion resistance, low cost (67 less dense than steel);d&antages: low cost, easil melted, free2flowing li#uid, lowolidification shrin!age; %isad&antages: high solidification temp,ensiti&e to solidification ratei)e types: hite 7ron2 relati&el hard and brittle, increasedear and corrosion resistance, used for rolling mills, grindingates, cement miers, etrusion dies> Gray 7ron2 mostommon, graphite fla!es form, low solidification rate, high

machinabilit and wear resistance, good oil retention andampening> &+ctile 7ron 2 similar properties to gra ironscept stronger and tougher> *allea-le 7ron2 formed bnnealing white iron (contain irregular graphite nodules called

mallebali-ation)> Compacted Graphite 7ron2 propertiesetween gra and ductile irons, good for high2temperaturepplicationshapter 1