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RichardE.Eitel
TeachingAssociateProfessor
Email:[email protected]
Office:Burchard307B
DepartmentofChemical
EngineeringandMaterials
Science
StevensInstitute
of
Technology
E344:MaterialsProcessing
IntroductiontoMaterialsScience
andEngineering
2
Introductions
Coursestructure&learning
approachandobjectives.
Thisclassperiodwillservesasanintroductiontothecourse
andMaterials
Science
&
Engineering
discipline.
Exploringstructure
propertyrelationships.
vs
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BorninClevelandOhio:
HOMEoftheBROWNSandtheRockandRollHallofFame!
Undergrad:AlfredUniversity(19941998)
B.S.in
Ceramic
Engineering
SouthernTierofNewYorkState
HomeoftheSaxons
X
Nowhere
Alfred
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PennState:19992006
MaterialsResearchInstitute
MaterialsResearchLaboratoryFoundedin1956:
1stInterdisciplinaryResearchLabinMaterialsScience
Ph.D.inMaterialsScienceand
Engineering:
Thesis:
NovelPiezoelectricCeramics:DevelopmentofHigh,Temperature,HighPerformance
Materials
on
the
BasisofToleranceFactor
UniversityofKentucky(20062013)
Teaching: DepartmentofChemicaland
MaterialsEngineering IntroductiontoMaterials CeramicEngineering MaterialsCharacterization ThreedifferentlabcoursesResearch:
PiezoelectricMaterialsMicrofluidics
MaterialsSynthesis Sensing
Biofluidics
CellBasedSensors
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Pastimes:AsinthingsusedtodobeforeIstartedteaching!
2015NYC
Marathon?
Yearsofeducationalresearchshowsthattheaverageanindividuals
averageattentionspaninapassivelectureisabout15minutes.
Learning howeverrequiresnotjustattentionbutactivethought!
After15minuteofLecture LearninginanActiveClassroom
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TeambasedGuidedInquiry
9
1. Breakinto
groups
of
3or
4.
2. Rearrangeseatsotheyoucantalk
comfortably.
3. Onestudentineachgrouplogonto:
m.socrative.com
4. Room#129851
GuidedInquiryI:Heat(10minutes)
UseFigure1.1.1toanswerthefollowingquestions(workasagroup
makesureeveryoneagreesbeforemovingtothenextquestion):
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ConceptCheckI:
Ahotpieceofcopperisplacedincontactwithacoldbrick?
Ifthecopperloses5caloriesofenergy,howmuchenergy
doesthe
brick
gain?
Guided Inquiry II:
Heat and Work (10 Minutes)
Heat
Transfer of energywhen there is adifference intemperature.
Work Transfer of energywhen there is nodifference intemperature.
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ConceptCheck:
AccordingtotheFirstLawofthermodynamics,couldheatbetransferredfromacoldobjecttoahotobject,resultinginthehotobjectgettinghotterandthecoldobjectgettingcolder'?
14
GuidedInquiryIII:ActiveLearning
(10minutes)
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RichardE.Eitel
AssociateProfessor
Email:[email protected]
Office:Burchard307B
DepartmentofChemical
EngineeringandMaterials
Science
StevensInstitute
of
Technology
E344:MaterialsProcessing
01 IntroductiontoMaterialsScience
andEngineering
Bytheendofthislectureyoushouldbeableto:
Theoverallobjectistointroducethefieldofmaterials
science
and
engineering.
Appreciatetheinterdependence
ofstructure,processing,
properties,andperformancefor
materialsdesignandselection.
Classifymaterialonthebasisof
structureandbonding.
Beabletopredictbondingand
materialpropertiesbasedonthe
atomicstructure.
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Thegoalofmaterialsscienceandengineeringistodescribethe
structure,processing,andpropertiesrelationshipwhichdictatethe
performanceofamaterialforaspecificengineeringapplication.
Acompletestructuraldescriptionofanengineeringmaterial
may
span
length
scales
from
the
nano to
the
macro.AtomicStructure:
10 m
BondingandCrystalStructure:
10 10 m
Macrostructure:
10
Microstructure:
10 10 m
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Materialspropertiesarecharacteristicswhichareintrinsic
tothematerialandformthebasisformaterialsselection.
PERFOMANCEREQUIREMENT:
Supporta6000poundtruck TensileStrengthofHardenedSteel:250,000PSI
Materialspropertiesareinputsinordertodesignacomponentto
achievesuitableperformanceinagivenapplication.
HighTensionWire:
PerformanceSpec:90%lighttransmission
MaterialProperty:
TotalHipReplacement:
PerformanceSpec:20yearlife
MaterialProperty:
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Processingincludestheentirehistoryofamaterialrequired
toforminintoacomponentwiththerequiredperformance.
ProcessingimpactBOTHtheSTUCUTREandthePROPERTIES
Theperformanceofamaterialinagivenapplicationisa
consequenceofcarefulmaterialsselectionandengineeringofthe
materialinto
acomponent.
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Materialsclassificationmaydependonwhetherwearetryingto
developunderstandingofselectamaterialsforagivenapplication.
StructuralClassification ApplicationsBasedClassification
Structural
Classification
Ceramics
Polymers
Composites
Metals
Thetraditionalclassificationofmaterialintoceramics,polymers,
metals,andcompositionisprimarilyonthebasisofatomicbonding
andstructure. Ceramics:
Inorganic,nonmetallicsolids
composedofasleastone
metallicandonenon
metallicatom.
Polymers:Macromoleculesformedby
covalentbondingofsimpler
molecularrepeatunits.
Metals:
Pureandalloyedatomic
speciesheldtogetherby
metallicbonding.
Composites:
Twoormoreoftheabovecombined
toproduceanewmaterialwith
uniquepropertiesorcombinations.
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Metals
Consistofpureandalloyedatomsheldtogetherbydelocalizedelectronsthatovercomethemutualrepulsionbetweentheioncores(MetallicBonding)Excellentstructuralmaterials:
high strength, toughness
(resistance to impact)
Electrical,thermalconductors
Atomsarrangedinregularlydefined,
repeatingpositionsthroughoutstructure
Steel:An alloy of iron, containing various amounts of carbon,manganese, and one or more other elements, such as sulfur,
nickel, silicon, phosphorus, chromium, molybdenum, andvanadium. These elements, when combined with iron, formdifferent types of steels with varying properties.
Metals?
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CeramicsandInorganicGlassesInorganic,nonmetallicsolids,composedofacombinationofoneormoremetallic
andoneormorenonmetallicatoms:
Al2O3 (alumina);
SiO2 (quartz, glass)
Mixedatomicbonding(ionicandcovalent)
Highstrength(compression),butbrittle
Excellent(electrical)insulators
Highthermalresistance;resistancetochemicalattack
High-end application: ceramic
tiles for use as heat shield inaerospace vehicles (> 1600C)
Ceramics?
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PolymersMacromoleculesformedbycovalentbondingofsimplermolecularrepeatunits(mers)Easilyprocessedtoawiderangeofshapes,dimensions
Moderatestrength;goodductility. Lightweight.
Usuallynotsuitableforhightemperatureapplications
(>100to200C)
polyethylene
polypropylene polystyrene PVC
Polymers?
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CompositesTwoormorematerialscombinedtoproduceanewmaterialwith
desiredproperties(newpropertiesareaveragedvaluesof
components)
Lowtechexamples:
plywood(panelcomprised
ofmultiplelayersofwood
veneer,plusadhesive;grain
laidat90angles)
concrete(cement[binder]
plussandandgravel)
steelbeltedtires(steel
belts,polyestercord,
rubber)
Hightechexamples:
carbonfiber
epoxy
composites
ceramicfibermetalmatrix
composites(SiC fibersinAl)
Innovation:
Boeings new 787 DREAMLINER is bepredominantly carbon fiber epoxylaminate, yielding a savings of ~20% infuel costs owing to weight reduction.
Alternativelymaterialsmaybeclassifiedandselectedbasedon
theirfunctionorsuitabilitytoaparticularengineeringneed.
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RichardE.Eitel
AssociateProfessor
Email:[email protected]
Office:Burchard307B
DepartmentofChemical
EngineeringandMaterials
Science
StevensInstitute
of
Technology
E344:MaterialsProcessing
02 GuidedInquiryAtomicBonding
Bytheendofthislectureyoushouldbeableto:
Theoverallobjectiveofthesesessionistodescribehow
atomic
structure
leads
to
bonding
in
materials.
DefineElectronegativity
Predictthedistributionof
electronsinabond.
Predictthetypesofbonds
formedindifferentatomsand
theirproperties
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Thestructureofmaterialsandtheircorrespondingpropertiesarise
duetotheelectronicstructureoftheconstituentatoms.
Electronicstructure
inmetals
allows
planesofatomsto
slidepasteachother
Electronconfigurationina
hightemperature
superconductor.
In1913Bohrclarifiedthestructureoftheatombytheorizing
electronswereconfinedtospecificallowedstates(orbits).
Explainssimpleemissionspectraofgases.
Allowedenergylevelsina
hydrogenlikeatomarelimitedto
integralvaluesofn:
Where:
h PlanksConstant
massof
an
electron
q fundamentalcharge
permittivityoffreespace
n energylevel(shell)
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Electrontransitionsbetweenallowedstatesareaccompaniedby
theadsorptionoremissionofaquantaorpacketofenergy,for
exampleinthefromofaphoton.
Ionizationenergy(IE)requiredto
removeaboundelectroninthestateyieldingafreeelectron
Allowedenergylevelsinasingle
electronatomwith
effectiveatomic
numberZ:
8
Atomswithmorethanhalffilledoutershellswill
tendtoATTRACTmoreelectronstocreateafull
outershell:Electronegative
Atomswithlessthanhalffilledoutershellswill
tendtogetridofouterelectrons:Electropositive
These
outer
VALANCE
electrons
lead
BONDING.
Emptyandcompletelyfilledshellshavelowerenergythanpartially
filledshells.ThusVALANCEelectronintheoutermostorpartially
filledshell
tend
to
be
particularly
active.
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Therelativetendencyofanelementtogainorlooseelectronsis
quantifiedaccordingtoitselectronegativity .
Atomswith
relatively
high
values
of
:
__________________
Atomswithrelativelylowvaluesof:__________________
Electronegativity=affinityofatomsforelectrons
Atomwithhigherelectronegativityhasastrongerpullonelectrons.
Electrons are closer to atom with higher electronegativity
GuidedInquiryI:Electronegativity
(10
minutes)
m.socrative.comRoom#129851
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A. FeBr
B.BrBr
C. KBr
D.CBr
E. Idontknow
ConceptCheck#1:In which of the following bonds are the electronsmost strongly pulled to one of the atoms?
m.socrative.comRoom#129851
A. FeBr
B.BrBr
C. KBr
D.CBr
E. Noneof
the
above.
F. Idontknow.
ConceptCheck#2:
In which of the following bonds are the electronsdistributed evenly between the two atoms?
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GuidedInquiryII:TypesofBond
(12minutes)
A.Covalent
B.Ionic
C.Metallic
D.Idontknow
ConceptCheck#3:
What are the primary bonds in the compoundCaF2?
m.socrative.comRoom#129851
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A.Covalent
B.Ionic
C.Metallic
D.Idontknow
ConceptCheck#4:What are the primary bonds in the compoundGaN?
m.socrative.comRoom#129851
GuidedInquiryIII:BondCharacter(12minutes)
%IonicCharacter % :
OnlyConsidersIonicand
CovalentBonding
Type of Bond How do you know?
% 100% 1 exp
4
ElectronegativityDifference
:
BondTypeTriangle:
ElectronegativityDifferenceover
AverageElectronegativity
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A. 0%ionic
B. 22%ionic
C. 68%ionic
D. 100%Ionic
E. Idontknow
ConceptCheck#5:What is the ionic character of the bond formed inthe compound FeBr2?
m.socrative.comRoom#129851
A. Ionic
B. Covalent
C. Metallic
D. Idontknow
ConceptCheck#6:
What is dominant primary bond type in thecompound FeBr2?
m.socrative.comRoom#129851
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RichardE.Eitel
TeachingAssociateProfessor
Email:[email protected]
Office:Burchard307B
DepartmentofChemical
EngineeringandMaterials
Science
StevensInstitute
of
Technology
E344:MaterialsProcessing
03 Crystallography:
lattices,directions&planes
Identifythesevencrystal
systems.
Distinguishbetweenacrystal
system,apointlattice,anda
crystalstructure.
Thegoalofthislectureistodeveloptheskillsrequiredto
describeand
define
the
structure
of
crystalline
solids.
AssignMillerIndicesto
directions[UVW]and
planes(hkl).
Bytheendofthislectureyoushouldbeableto:
vs vs
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Accuratelydescribingtheorderedstructureofcrystalline
materialsrequiresidentifyingseverallayersofstructure.
CrystalStructure
space
filling
polyhedra
PointLattice referencepointsdescribing
symmetricallyequivalentpositions
Basis Atomoratomiccomplex
CrystalStructure
lattice+basis
Therearesevenunique3Dcrystalstructureswhich
encompassall
possible
space
filling
polyhedral.
6Lattice
parameters:
Edges:a,b,c
Angles:, ,ab
NOPOINTSinacrystalstructure!
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The14Bravais pointlatticesincludethelocationsofthe
symmetryequivalentpoints(referencepositions)within
thesevencrystalsystems.
Auguste Bravais
18111863
Latticepoints atoms
Primitivelattices(P)haveexactlyonelatticepointperunit
cell.
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Nonprimitivelatticeshavemultiplepointsperunitcelland
mayincludebodycentered(I),facecentered(F),andend
centered(ABC)types.
PPrimitive F FaceCentered I Body
Sincealllatticepointshaveidenticalsurroundingsthe
choiceof
the
origin
is
arbitrary.
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Toconstructacrystalstructureamotifofbasisunitis
assignedtoeachlatticepoint.
Basis
Lattice Motif (Basis) CrystalStructure+ =
TheSAMEmotifmustbeassignedtoEVERYpointinthe
lattice.
BodyCenteredLatticewith
1AtomPerPoint
SimpleCubicLattice
With2AtomsPerPoint
VS.
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Differentmotifscanproduceverydifferentcrystal
structuresfromthesamelattice.
Positions,directions,andplanesincrystalstructuresare
distinguishedby
maintaining
aspecific
convention
unique
toeach.
Positional
Coordinates:,1,
Direction
Vectors:
Planar
Indices:
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Conventionistodefinearighthandedcoordinatesystemin
whicheachoftheunitcelledgesa,b,andchaveunit
length.
90
90
Specificpositionsaredesignatedusingthecoordinatesh,k,andlwhere
each
value
represents
afraction
of
the
lattice
parametera,b,andc,respectively.
Findthecoordinatesforthe
following:
PointD:
PointC:
PointH:
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DirectionsarespecifiedbylowestintegersvaluesU,V,and
Walongunitvectors,,and andenclosedinsquare
brackets
.
111
Specifiesonlydirection
NOTmagnitude...
Assigningdirectionalindicescanbeperformedbyfollowing
theprocedure:
1. Usingarighthandedcoordinatesystem,determinethe
coordinatesoftwopointsthatlieonthedirection
2. Subtractthepositionofthetailpointfromthecoordinatesof
theheadpoint,toobtainthenumberoflatticeparameters
traveledineachdirection
3. Clearfractionsand/orreducethedifferences,togive(lowest)
integervalues.
4. Writeindicesinsquarebrackets[UVW] (nocommas)
5. Indicatenegativevalueswithoverbar.
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Practice: FindthedirectionindicesforvectorEOatleft:
Findthedirectionalindicesfor
thefollowingvectors(atright):
VectorOA:
VectorOF:
VectorCB:
ImportantNotesaboutDIRECTIONS:
ADIRECTIONanditsnegative
areNOTthesame!
Multiplesofdirections
AREidentical!
(Reducebyconvention) =
Certaingroups
or
familiesofdirections
andtheiroppositesare
equivalent.
Cubic : , , , , , ,
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1
Millerindicesofplanesaredenotedbyintegersh,k,andl
enclosedinparenthesis .
MillerPlanesaredeterminedusing
1. Chooseaplanethatdoesnotpassthroughtheoriginat:0,0,0moveoriginifneeded.
2. Determinefractionalintercepts oftheplanewiththe
crystallographicaxesx,y,andz.
forplanesparalleltoanaxestheinterceptis
3. Takereciprocaloftheintercepts.
4. ClearfractionsbutDONOTREDUCEtolowestintegers.
5. Citeplaneswithparenthesis indicatenegativevalueswithoverbar.
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1
ExamplesandPracticewithPlanes:
ImportantNotesaboutMillerindicesforplanes.
Planesandtheir
NEGATIVES areidentical!
PlanesandtheirMULTIPLES
areparallelbutNOT
identical!
Equivalentfamiliesofplanes
areindicated
by
Braces
{hkl}:
Family : , , , , ,
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RichardE.Eitel
AssociateProfessor
Email:[email protected]
Office:Burchard307B
DepartmentofChemical
EngineeringandMaterials
Science
StevensInstitute
of
Technology
E344:MaterialsProcessing
04 CrystallineSolids
2
Thegoalofthislectureistodeveloptheskillstodescribe
andpredict
both
structure
and
properties
of
crystalline
materials.Bytheendofthislectureyoushouldbeableto:
Describethecrystalstructuresof
severalcommonengineeringmetals
andceramics
Estimatedensitiesofbothmetal
andceramicmaterialsusingonly
theirknowncrystalstructure.
Useatomicradiitopredictthe
structureofsimpleionic
compounds.
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1.Yes
2.No
3.Imnotsure
ConceptCheck:CanyouIdentifyCommonUnitCellsand
Calculatetheirassociatedproperties(latticeparameter,
mass,volume, density,etc)?
GuidedInquiryI:CrystalsandGlasses
(5
minutes)
Hypotheticalarrangementofatomsinacrystalandaglass.
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1.Itwouldbedifferent.
2.Itwouldbethesame.
3.Idontknow.
ConceptCheck:Aglassrodhasastiffnessof70GPa when
pulledalongitslength.Howwouldyouexpectthestiffness
tochangeifyoupulleditperpendiculartoitslength?
Crystalstructuresareusedtodescribethelongrange
periodicitypresent
in
crystalline
materials.
LongRangeOrder: ShortRangeOrder:
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Crystallinematerialsrepresentthestablelowestenergy
stateofanysolid.
Dense,regular
packing
Typicalbondlength
Typicalbondenergy
Nondense,
random packing
Typicalbondlength
Typicalbondenergy
GuidedInquiryII:CrystalUnitCells
(10
minutes)
SimpleCubic
(SC)
BodyCentered
Cubic
(BCC)
FaceCentered
Cubic
(FCC)
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1. 1
2. 2
3. 3
4. 6
5. Idontknow.
ConceptCheck:Forthecrystalstructureshown,
howmanyblueatomsarethereperunitcell(i.e.,
withinthe
unit
cell)?
1. 1
2. 2
3. 4
4. 8
5. Idontknow.
ConceptCheck:Forthecrystalstructureshown,
howmany
green
atoms
are
there
per
unit
cell
(i.e.,
withintheunitcell)?
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TheUNITCELListhesmallestessentialunitofacrystalline
material.
UnitCell
of
Cesium
Chloride
Keycharacteristics ofaunitcell:
Dimensionsspecifiedbysixlattice
parameters, ,, ,,
Basedononeofthe14Bravais
lattices
Includesexactlyonebasisateach
latticepoint
Repeatsindefinitelyinall
direction Canbeusedtocalculatethe
densityofthecrystallinephase
Mostmetaltypicallyassumeoneofthreebasiccrystal
structures.MetalswiththeBodyCentered
Cubic(BCC)structureinclude:
Tungsten,chromium,iron,
molybdenum,vanadium
MetalswiththeFaceCentered
Cubic(FCC)structureinclude:
aluminum,calcium,copper,gold,
lead,nickel,platinum,silver
MetalswiththeHexagonalClose
Packed(HCP)structureinclude:
Cadmium,Titanium,Zinc,
Magnesium,Cobalt
BCC
FCC
HCP
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GuidedInquiryIII:AtomicPackingFactor
(10minutes)
= lattice
parameter
R = atomicradius
SC BCC FCC
AtomicPacking
Factor(APF):
A. 0.52
B. 0.68
C. 0.74
D. 1.00
E. Idontknow
ConceptCheck:Whatistheatomicpackingfactor
(APF)for
aSC
unit
cell?
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GuidedInquiryIV:Density
(10minutes)
SC BCC FCC
A.
B.
C.
D. /
E. Idontknow
Concept Check: What is the
relationship between a and R for anFCC unit cell?
FCC
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Ceramiccrystalstructuresarebasedoneitherionicor
covalentbondingoftheconstituentspecies.
ConsiderCovalent
bonding:Consider
an
ionically bonded
ceramic
GuidedInquiryV:InterstitialSites
(10minutes)
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1
A. Originalatoms
B. Interstitialatom
C. Idont
know
Concept Check: Basedontherelativesizesofanionsandcations,ifthiswereanioniccompound,
whichatoms
would
be
the
anions;
the
original
atomsatthecornersoftheunitcell,orthe
interstitialatomyouadded?
Consideringtheclosestpackingofatomsonly74%ofthe
spaceis
occupied,
these
holes
or
interstices
offer
sites
for
additionalatoms...impurities,dopants,compounds...
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1
Inionically bondedceramicsstablecrystalstructuresmust
balancetheelectrostaticinteractionsofoppositelycharged
ions.
+
+
+
Cations willsurroundthemselveswiththe
maximumnumberofoppositelycharged
anionspossible!
Radiusratioscanbeusedtopredictthenumberofnearest
neighbors(Coordination
number)
of
various
sized
cations.
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1
GuidedInquiryVI:DensityofCeramics
(10minutes)
A.
B.
C.
D. +
E. Idontknow
Concept Check: What is the general
formula for the lattice parameter of athe rock salt structure?
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RichardE.Eitel
AssociateProfessor
Email:[email protected]
Office:Burchard307B
DepartmentofChemical
EngineeringandMaterials
Science
StevensInstitute
of
Technology
E344:MaterialsProcessing
05 StructureandProperties
ofPolymers
2
Thegoalofthisdiscussionistobeabletodescribethe
macromolecularstructure
of
polymers
and
relate
this
to
theirengineeringproperties..Bytheendofthisdiscussionyoushouldbeableto:
Describetheroleofpolymerchain
lengthonkeyengineering
properties.
Classifythebasicstructuresof
polymerchains.
Predicttrendsinthecrystallinity
andpropertiesofpolymerbasedon
theirmolecularweightandchain
structure.
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Polymersaregiantmacromoleculesconsistingof10sto
many1,000sofcovalentlybondedrepeat(mer)units.
mer
GuidedInquiryI:AverageMolecularWeight
(10
minutes)
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A. 0.0012
B. 831.75
C. 832
D. 1,472,800
E. I don't know.
ConceptCheck:What is the DP for polypropylene with amolecular weight of 35,000 g/mol?
m.socrative.comRoom#129851
A. B. g/C. D. It is unit less
E. I don't know.
ConceptCheck:
What are the units for DP?
m.socrative.comRoom#129851
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Thechainlengthofpolymersischaracterizedbythedegree
ofpolymerization(DP)andthemolecularweight.
PolymersareALWAYSmixtureofmacromoleculesof
varyingmolecularweights
NumberAverageMolecularWeight
:
Where:
isthemedianmolecularweightofachainintheithsizerange.
isnumberfractionofchainsintheithsizerange isweightfractionofchainsintheithsizerangeismolecularmassoftherepeat(mer)unit
=
WeightAverageMolecularWeight:
Degreeofpolymerization(DP):
Polydispersity Index(PDI):
0
0.05
0.1
0.15
0.2
0.25
FractionalContent
MolecularWeightRange(g/mol)
FractionalDistrubtionofMolecularWeights
WeightFraction(wi)
NumberFraction(ni)
GuidedInquiryII:MolecularWeightCalculations
(8
minutes)Considerasampleofplasticwhichyouknowis15mol%polymer
moleculeswithmolecularweight500,000g/mol,and85mol%
polymermoleculeswithmolecularweight150,000g/mol.
NumberAverageMolecularWeight:
WeightAverageMolecularWeight:
Degreeofpolymerization (DP):
Polydispersity Index(PDI):
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A. 119,600g/mol
B. 202,500g/mol
C. 280,000g/mol
D. Idontknow
ConceptCheck:What is the number average molecular weight forthe above mixture?
m.socrative.comRoom#129851
A. 119,600g/mol
B. 202,500g/mol
C. 280,000g/mol
D. Idontknow
ConceptCheck:
What is the weight average molecular weight forthe above mixture?
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A.Yes
B.No
C.isalwayslessthan.D.Idontknow
ConceptCheck#3:Can belessthan?Why?
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Formanysimplelinearpolymers,materialpropertiesare
dictatedby
chain
length
and
weak
secondary
bonding
betweenchains.
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GuidedInquiryIII:MWandProperties.
(5minutes)
Considertwodifferentplatesofspaghetti.Oneinwhichallthe
strandsarethefulllengthandoneinwhichthestrandhavebeencutintoshortsegments.
A. 100,000 g/mol
B. 200,000 g/mol
C. Theyhavethesamestrength.
D. Idontknow
ConceptCheck#4:
Which has a higher strength; polyethylene of100,000 g/mol or 200,000 g/mol?
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ConceptCheck#5:Which flows more easily; polyethylene of 100,000g/mol or 200,000 g/mol?
m.socrative.comRoom#129851
A. 100,000 g/mol
B. 200,000 g/mol
C. Theyflowequally.
D. Idontknow
Polymersmayalsobecharacterizedbychainlengthand
meanend
to
end
Distance.
Total(stretchedout)chainlength(L):
2Meanendtoenddistance(r):
Where:
d bondlength
N numberofbondsinchain
anglebetweenadjacentatoms
=109.5o forCC
L
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Thepropertiesoflinearpolymerscanbemodifiedby
introducingbranchingorcrosslinking.
Linear
secondary
bonding
Branched
Cross-Linked Network
Likemetalsandceramicspolymersmayexhibithighly
orderedcrystalline
regions.
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1
GuidedInquiryIV:PolymerCrystallinity.
(10minutes)
a) Polyethyleneorpolystyrene.
b) Polyethylenewithmanylongbranchesorpolyethylene
withafewshortbranches.
c) Atactic polypropyleneorisotacticpolypropylene.
d) Polypropyleneorpoly(ethyleneterephthalate)(PET).
e) Polyethyleneorarandomcopolymerof50%ethylene
repeatunitsand50%propylenerepeatunits.
f) PETmeltedandrapidlycooledtoroomtemperatureor
PETmelted,cooledto150 C,heldtherefor1hour,and
thencooledtoroomtemperature.
Reportout:
Which of the following pairs is more crystalline?
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Theproductionofmostpolymermacromoleculesfrom
theirmonomeroccursbyoneoftwopolymerization
routes.
Addition(Chaingrowth)
polymerization:
Condensation(stepreaction)
Polymerization
(byproductproducedoftenwater)
Initiatormonomer
Polyethylene:
Polyethyleneterephalate
Thermoplasticpolymersaretypicallylinearorslightly
branchedand
soften
on
heating
allowing
them
to
be
easily
(re)formedandreadilyrecycled.
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Thermosetpolymersreactonmixingorunderactionof
heatformingextensivecrosslinks.
Example: Bakelitefirstcompletely
syntheticplastic,
1907.
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RichardE.Eitel
AssociateProfessor
Email:[email protected]
Office:Burchard307B
DepartmentofChemical
EngineeringandMaterials
Science
StevensInstitute
of
Technology
E344:MaterialsProcessing
06 MaterialsCharacterization
Methods
Theoverallobjectivethislectureistogiveyoutheskillstoapply
severalofthemostwidelyusedmaterialscharacterization
methods:
Bytheendofthislectureyoushouldbeableto:
Calculateinterplanar spacings inmaterialspossessingacubiccrystalstructure.
UseBraggsLawtorelateexperimentaldiffractiondatatointerplanar spacing.
CalculatemeangraindiameterandATSMgrainsizefrommicrostructureimages.
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Diffractionistheapparentbendingofwavesaround smallobjects
andthespreadingoutofwavebeyondsmallopenings.
Beyondan
Opening Around
A
Corner
Theapparentspreadingduetodiffractiondependsonthe
wavelength
of
the
wave
or
particle.
SpreadingofWhiteLightSource DispersionofSoundWaves?
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Youngsdoubleslitexperimentrevealedunexpected
propertiesoflightandquicklymovingparticles.
https://www.youtube.com/watch?feature=player_detailpage&v=Iuv6hY6zsd0
Theperiodicityofinterferencepatternsproducedby
diffraction
experiments
are
related
to
the
geometry
of
the
slitorstructurecreatingthepattern.
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GuidedInquiryI:BraggsLaw
(10minutes)
Ifconstructiveinterferenceoccursfromtwoplanesofatomsforascatteringangle(theta)of20.0degreeswhatisthedistance(d)betweentheplanes,ifthethewavelengthofthewavesis0.154nm?
A. 0.450nm
B. 0.225nm
C. 0.119nm
D. 0.0843nm
E. Idontknow
ConceptCheck:
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Theconditionforconstructiveinterferencefromequally
spacedlayersisgivenbyBraggsNoblePrizeWinningLaw.
ConstructiveInterferencefor
ABC=n*lambda
1912@21YearsOld!
d
WhataretheconditionsforwhichdiffractionOccurs?
2
Considern=1
2
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Whataretypicalspacings (dspacings)betweenatomic
planes?SimpleRelationshipsexistdepending
onthe
crystal
system
of
the
crystal
structure:
General(othorhomic)
+
Cubic(a=b=c):
Tetragonal
:
GuidedInquiryII:Interplanar Spacings
(10
minutes)
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Diffractionexperimentscanbeusedtodescribethestructureand
atomicpositionsinbothsingleandpolycrystalmaterials.
PowderDiffraction
with
Area
DetectorSingleCrystalDiffraction
Powderdiffractionisusedtocollectdataonthefullsetof
interplanar spacing
by
equally
sampling
all
orientations.
PhotographicMethod DigitalMethod
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GuidedInquiryIII:DiffractionExperiments
(10minutes)
Dependingonthecrystalstructurenotallsetofplanes
produce
diffraction
events.
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Microscopyisusetorecordgeometricalstructureand
orientationofmaterialsatthemicroscopicscale(
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Opticalmicroscopesusevisuallighttocreateimagesand
characterizetheopticalpropertiesofmaterials.
PracticalResolution
Limit:
~1micron
IdentificationofMineralsbyOpticalProperties:
BoneCancer
Cell
Image:Nikon2012SmallWorld
Intransmissionelectronmicroscopyhighenergyelectrons
are
use
to
achieve
atomic
scale
images
of
thin
(~10nm)
sectionsofmaterial.
ResolutioninaTEM:
HighEnergyElectrons:
1
@300KeV~ 2.0 pm
Schematic
PracticalResolutionlimit:
0.08nm~1
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TEMscanbelargebutarealwaysEXPENSIVE!
HVEMJEOL1.25MeV
FEITitan300KeV
>$3MILLION
USD??
Scanningelectronmicroscopeelectronicallyacquireanimageby
scanning(rastering)afocusedbeamofelectronsacrossasample
surface.
Resolutionlimit:
ProbeSize
Interactionvolume
~1nm
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Scanningelectronmicroscopesarehavebecometheworkhorse
microscopeofchoiceforroutinematerialscharacterization
MinimalSample
Prep
CompatiblewithSizeofFeatures
ReasonableCost:
$100K500K
Thechoiceofmicroscopicmethodsdependsonthescale
and
type
of
information
the
is
needed!
ThefollowingareimagesofCarbonnanotubes:
OpticalMicroscope(Fluorescence):30Mnanotubefilamentusedforsolarenergyharvesting
ScanningElectronMicroscope:Bundlesofnanotubes.
TransmissionElectronMicroscope:atomicspacinginasinglemultiwallnanotube
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MicrostructureAnalysis