Surface modification of sodium aluminosilicate glasses using microwave energy

316 Pages·1994·10.5 MB·English

by  Fathi, Zakaryae, 1966-

SURFACEMODIFICATIONOFSODIUMALUMINOSILICATE
GLASSESUSINGMICROWAVEENERGY
By
ZAKARYAEFATHI
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1994
Copyright1994
by
ZakaryaeFathi
Iwouldliketodedicatethisdissertationtomy
grandmotherwhoseloveandnurturingmademewhoIam.
ACKNOWLEDGEMENTS
Theauthorwishestoexpresshissinceregratitudetoanumberofpeoplefor
theirsupport,suggestionsandcontributionstowardsthisstudyaswelltomypersonal
well-being. First,IwouldliketoexpressmyindebtednesstoDr.DavidClark,my
teacherandmymentor.Heintroducedmetothefieldofmicrowaveprocessingand
guidedme throughmyacademiccareeratthe UniversityofFlorida. Hissincere
concernwasappreciatedinmanyareaswhichincludethequalityofthiswork,my
academicgoalsaswellasmypersonallife.
IwouldliketoalsothankDrs.J.H.Simmons,E.DowWhitney,M.Kaufman
and R.J. Hanrahan for their useful comments, suggestions, encouragement and
patience. SpecialthanksgotoDr.RonHutcheonoftheAtomicEnergyofCanada,
Ltd.,ChalkRiverLaboratoriesforhisinvaluableassistanceinobtainingdielectric
measurements and Dr. A.R. Lodding of Chalmers University of Technology,
Gothenburg,Sweden,forprovidingandinterpretingtheSIMSdata.
The author is grateful to Wayne Acree of the Major Analytical
InstrumentationCenterattheUniversityofFloridaforhischeerfulassistanceand
expertelectronmicroprobemeasurements. IwouldalsoliketothankGuyLaTorre
forhisinvaluabletechnicalassistance.
IV
SpecialthankstoRebeccaSchulzforherfriendshipandinvaluableassistance.
SpecialrecognitionisextendedtoIftikharAhmadforhisguidance andthemany
hoursofstimulatingdiscussions.
IwouldliketothankallofmypresentandformerassociatesinDr.Clark's
researchgroup,theDepartmentofMaterialsScienceandEngineering,SalwanAl-
Assafi, Attapon Boonypiwat, Alex Cozzi, Robert Dalton, Arindam Db, Robert
DiFiore, DianeFolz, CarlJones, PaulKomarenko, Edmund Moore,Khalid Raji,
Soo-Man Sim, Lorie Stapler, Michael Vincent, Jipin Zhong and Bruce Zoitos.
Specialthanksgotoallmyfriends,especially,KhalidMentak,HassanOukachaand
MoncefBelkhyat.
Ialsowouldliketothankmyparents,brothers,sisters,andallthemembers
ofmyextendedfamilyfortheirconstantlove,devotionandmoralsupport. Special
thanksareextendedtoHamidSaidiforalwaysbeingthereformeandforhelping
meachievemygoals. IwouldliketothanktheGilbertfamilyformakingmefeel
likeamemberoftheirfamily. Finally,Iwouldliketoexpressmysinceregratitude
tomyfianc£,SueS.Gilbert,forherunderstanding,loveandsupport.
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TABLEOFCONTENTS
ACKNOWLEDGMENTS
iv
ABSTRACT
x
CHAPTERS
INTRODUCTION
1. 1
1.1ConventionalVersusMicrowaveHeating 2
1.2OxideGlasses 4
1.3SurfaceModificationUsingMicrowaveEnergy 7
1.4DissertationOverview 8
BACKGROUND
2. 9
Introduction 9
2.1 Microwaves 9
2.1.1 MicrowaveGeneration 17
2.1.1a Magnetrons 17
2.1.1b Klystrons 20
2.1.1c Travelingwavetubes(TWT) 25
2.1.Id Backwardwaveoscillatorsandcross
fieldamplifliers 27
2.1.1e MASERs 27
2.1.2 Waveguides 28
2.1.3 Applicators(Cavities) 41
2.1.3a Thequalityfactorofacavity,Q 47
2.1.4 HistoryofMicrowaveProcessing 49
2.1.5 AllocatedFrequencies 52
2.1.6 ProtectionandSafety 55
2.1.6a Healthhazardstohumans 57
2.2 TheoreticalAspectsofMicrowaveHeatingand
Microwave/MaterialsInteractions 59
2.2.1 DielectricMaterials 61
2.2.2 FrequencyDependenceofthePolarization 63
vi
2.2.3 TheComplexNatureoftheDielectricConstant . 69
2.2.4 PolarizationMechanismsVersusLoss 78
2.2.4a Orientationpolarizationversusloss 78
2.2.4b Spacechargepolarizationversusloss 92
2.2.5 ConductivityLosses 98
2.2.6 MagneticLossFactor .' 100
2.2.7 MicrowavePowerDissipation 100
2.2.7a Penetrationdepth 102
2.2.7b Rateoftemperaturerise 104
2.2.7c Thermalrunaway 104
3. GLASSESANDGLASSPROPERTIES 110
Introduction 110
3.1 GlassFormationandStructure Ill
3.2 IonicTransportinOxideGlasses 116
3.3 TheSodiumAluminosilicateGlassSystem 119
3.4 SurfaceModificationandGlassStrengthening 125
3.5 DielectricLossesinGlasses 130
4. EXPERIMENTALPROCEDURES 135
4.1 MaterialsandMethods 135
4.1.1 TheGlassMatrix 135
4.1.2 GlassPreparation 135
4.1.2a Samplepreparation 136
4.1.2b Substratecleaning 136
4.1.3 IonExchangeProcess 136
4.1.3a Substratecleaningafterionexchange 138
4.1.4 ExperimentalSetupforHeatTreatments 138
4.2 MaterialsCharacterizationandAnalyticalTechniques . 144
4.2.1. ContactAngle 144
4.2.2. FourierTransformInfraredSpectroscopy(FTIR) 144
4.2.3 X-RayDiffraction 146
4.2.4 Pycnometry 146
4.2.5 Dilatometry 146
4.2.6 Microhardness 146
4.2.7 ElectronMicroscopy 148
4.2.8 SecondaryIonMassSpectroscopy(SIMS) 148
4.2.9 DielectricAnalyses 149
vii
5. RESULTS 152
5.1 TheNASGlassSystem 152
5.1.1.PhysicalProperties 152
5.1.2 DielectricAnalyses 155
5.1.3 IonExchange 190
5.1.3a K+forNa+ionexchange 190
5.1.3b Ag+ andK+forNa+ ionexchange 207
5.25T.h1.e4CTohrneinDigelGelcatsrsicSyBeshtaevmiorofKN03andAgN03... 221166
5.2.1 PhysicalProperties 221
5.2.2 DielectricBehavior 221
5.2.3 IonExchange 228
5.2.4 KnoopHardness 235
5.2.5 ContactAngleMeasurements 238
5.2.6 FTIRSpectroscopy 238
6. DISCUSSION 243
Introduction 243
6.1 TheStructureofNASGlasses 244
6.2 TheDielectricBehaviorofNASGlass 247
6.3 TheInterdiffusionReactions 251
6.3.1 SlurryIonExchange 252
6.3.1a TheCorningglasssystem 252
6.3.1b TheNASglasssystem 253
6.3.2 IonExchangeinMoltenSalts 255
6.3.3 EffectsofIonExchangeonHardness 256
6.4 ProposedMechanismsofEnhancedDiffusion 257
6.4.1 TheNonthermalMicrowaveEffect 267
6.4.2 TheLocalizedIonicTemperatureIncrease
Mechanism 270
6.4.3 TheHybrid(Thermal/Nonthermal)Microwave
Effect 274
7. SUMMARYANDCONCLUSIONS 276
Introduction 276
7.1 TheNASGlassSeries 277
7.2 TheCorningGlass 280
FUTUREWORK
8. 282
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APPENDIXI 284
APPENDIXII 290
APPENDIX
III 291
APPENDIXIV 292
REFERENCES
293
BIOGRAPHICALSKETCH 301
IX
AbstractofDissertationPresentedtotheGraduateSchool
oftheUniversityofFloridainPartialFulfillmentofthe
RequirementsfortheDegreeofDoctorofPhilosophy
SURFACEMODIFICATIONOFSODIUMALUMINOSILICATE
GLASSESUSINGMICROWAVEENERGY
By
ZakaryaeFathi
April 1994
Chairperson: Dr.DavidE.Clark
MajorDepartment: MaterialsScienceandEngineering
Microwave energy is becoming more important in the processing and
fabricationofmaterials. Microwaveheatingisuniqueandmayberegardedasan
alternativeprocessingmeansbywhichshorterprocessingtimesareoftenachieved.
Heat generation upon material irradiation with microwaves is internal and
volumetric. Thesethermaldistributionsmakeitpossibletorapidlyanduniformly
heat treat large ceramic bodies. Several ceramicsystems have been successfully
sinteredusingmicrowaveenergy. Thecommonlyobservedhighsinteringratesand
graingrowth are thought to be due to enhanced diffusion brought about by the
microwave field. However, experimental evidence to date has not provided the
empiricaldatanecessarytosubstantiatethisclaim.
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