High Temperature Experiments in Chemistry and Materials Science

343 Pages·2013·5.309 MB·English

by  Ketil Motzfeldt(auth.)

High Temperature
Experiments in Chemistry
and Materials Science
High Temperature
Experiments in Chemistry
and Materials Science
Ketil Motzfeldt
DepartmentofMaterialsScience
NorwegianUniversityofScienceandTechnology,
Norway
Thiseditionfirstpublished2013
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Contents
Foreword xiii
Preface xv
Acknowledgements xvii
1 IntroductiontoHighTemperatureResearch 1
Preamble 2
1.1 TheBasisofItAll 2
1.1.1 Photosynthesis 2
1.1.2 TheRoleofCarbon 3
1.2 HighTemperatures 3
1.2.1 ChemistryatAmbientTemperatures 3
1.2.2 ChemistryatHighTemperatures 3
1.2.3 TheNitrogenIndustry 4
1.2.4 IronandSteel 4
1.3 CarbothermalSiliconandAluminium 4
1.3.1 FerrosiliconandSiliconMetal 4
1.3.2 TheFirstLaboratoryFurnace 5
1.3.3 CarbothermalAluminium 5
1.3.4 MoreLaboratoryFurnaces 6
1.3.5 ANoteonChemicalThermodynamics 6
1.4 SummaryofContents 6
SelectBibliography 7
2 BasicDesignofLaboratoryFurnaces 11
Preamble 12
2.1 MethodsofHeating 12
vi CONTENTS
2.2 Materials 13
2.2.1 ElectricConductorsorResistors 13
2.2.2 InsulatingMaterials 15
2.3 BasicFurnaceDesign 17
2.3.1 ObtainingaUniformTemperature 17
2.3.2 BaseMetalWire 20
2.3.3 TheStandandAuxiliaries 24
2.3.4 SiliconCarbide 24
2.3.5 MolybdenumDisilicide 28
2.3.6 OxideResistors 28
2.3.7 NobleMetals 29
2.3.8 MolybdenumWire 29
2.3.9 Graphite 30
2.4 InductionHeating 31
2.4.1 ElementaryPrinciples 31
2.4.2 HighFrequencyGenerators 33
2.4.3 SomeLaboratoryApplications 34
2.5 PowerInput,InsulationandCooling 36
2.5.1 PowerandTemperature 36
2.5.2 ThermalInsulation 37
2.5.3 WaterCooling 40
2.6 TemperatureControl 44
2.6.1 ElementaryPrinciplesandTwo-Position
Control 44
2.6.2 PIDControl 46
2.6.3 PowerRegulators 47
2.6.4 SensingElementsforControl 48
2.7 ElectricConnectionsandCircuits 49
2.7.1 GeneralRules 49
2.7.2 Current-CarryingCapacityofInsulated
CopperWire 50
2.7.3 Fail-SafeProtectionDevices 51
References 53
3 TemperatureMeasurements 55
Preamble 56
3.1 FundamentalsofTemperatureMeasurement 56
3.1.1 TheConceptofTemperature 56
3.1.2 TheThermodynamicTemperatureScale 58
CONTENTS vii
3.1.3 TheGasThermometerandthePractical
TemperatureScale 60
3.1.4 HistoryoftheInternationalTemperatureScales 61
3.1.5 TheInternationalTemperature
Scaleof1990(ITS-90) 62
3.2 ‘Low-Temperature’Thermometers 64
3.2.1 Liquid-in-GlassThermometers 64
3.2.2 BimetallicThermometersandThermostats 65
3.2.3 Semiconductor-BasedThermometers 65
3.2.4 ResistanceThermometers 66
3.3 Thermocouples 66
3.3.1 PrinciplesofThermoelectricity 66
3.3.2 ThermocoupleMaterials 69
3.3.3 Base-MetalThermocouples 71
3.3.4 Noble-MetalThermocouples 72
3.3.5 InsulatingMaterialsandInstallation 75
3.3.6 MIMSThermocouples 77
3.3.7 ThermocouplesforVeryHighTemperatures 78
3.3.8 TheColdJunction 78
3.3.9 ExtensionandCompensatingWires 80
3.3.10 ControlandCalibration 81
3.3.11 TheMeasurementofSmalle.m.f.’s 86
3.3.12 MoreaboutThermoelectricity 88
3.4 Literature 89
References 90
4 RadiationPyrometry 93
Preamble 94
4.1 BasicPrinciples 94
4.1.1 TheNatureofHeatandRadiation 94
4.1.2 FormationandPropagation 95
4.1.3 TheConceptoftheBlackBody 97
4.1.4 Emission,AbsorbtionandKirchhoff’sLaw 98
4.1.5 TotalRadiation,StefanandBoltzmann 100
4.1.6 SpectralDistribution,WienandPlanck 100
4.1.7 TheRadiationLawasUsedinPyrometry 104
4.2 TotalRadiationPyrometry? 106
4.3 Disappearing-FilamentOpticalPyrometer 106
4.3.1 TheClassicalOpticalPyrometer 106
viii CONTENTS
4.3.2 TheAutomatedVersion 111
4.3.3 TheModernManual 112
4.4 PhotoelectricPyrometers 112
4.4.1 BasicPrinsiple 112
4.4.2 TheChoiceofWavelength 113
4.4.3 TargetSizeandFreeSight 114
4.4.4 Two-ColourPyrometers 115
4.5 CorrectionsforWindowandMirror 116
4.5.1 ReflectionandAbsorbtioninaWindow 116
4.5.2 TheUseofaMirror 118
4.5.3 GraphicalRepresentationofA-Values 120
4.6 ControlandCalibration 121
4.6.1 TungstenRibbonLamps 121
4.6.2 MeltingPoints 123
4.6.3 Metal-CarbonSystems 124
4.7 PracticalHints 125
4.7.1 TheObjectInsideaFurnace 125
4.7.2 MoreabouttheBlackBody 126
4.7.3 IncreasingtheApparentEmissivityofan
ExposedSurface 126
References 127
5 RefractoryMaterialsintheLaboratory 129
Preamble 130
5.1 Oxides 131
5.1.1 Silica,SiO 133
2
5.1.2 Mullite,3Al O (cid:1)2SiO 134
2 3 2
5.1.3 Alumina,Al O 135
2 3
5.1.4 Magnesia,MgO 136
5.1.5 Beryllia,BeO 136
5.1.6 Zirconia,ZrO 136
2
5.1.7 Thoria,ThO 137
2
5.1.8 GeneralNotesonMaterials’Properties 138
5.2 Carbides 139
5.2.1 SiliconCarbide,SiC 139
5.2.2 AluminiumCarbide,Al C 145
4 3
5.2.3 BoronCarbide,B C 146
4
5.3 Nitrides 147
5.3.1 SiliconNitride,Si N 147
3 4
CONTENTS ix
5.3.2 AluminiumNitride,AlN 149
5.3.3 Sialons 153
5.3.4 BoronNitride,BN 153
5.4 CarbonandGraphite 155
5.4.1 Carbon:TheElement 155
5.4.2 OccurrenceofCarbonaceousMaterials 156
5.4.3 CarbonandGraphite 157
5.4.4 VitreousCarbon 159
5.4.5 CarbonFibresandGraphiteFelt 160
5.5 RefractoryMetals 161
5.5.1 BaseMetalsandAlloys 161
5.5.2 NobleMetals 161
5.5.3 MolybdenumandTungsten 162
5.5.4 Tantalum 164
5.5.5 Rhenium 165
5.6 NotesonCrucibleMaterialsandCompatibility 165
5.6.1 ALineofThought 166
5.6.2 GraphiteplusMetals 166
5.6.3 CeramicsplusMetal 167
5.6.4 MoltenSaltsandSlags 167
5.6.5 ChemicalTransportReactions 168
5.6.6 SpecialMaterials 168
5.6.7 ANoteonSafety 171
References 171
6 VacuuminTheoryandPractice 175
Preamble 177
6.1 BasicConcepts 177
6.1.1 WhyVacuum? 177
6.1.2 UnitsofGasPressure 178
6.1.3 ElementsofaVacuumSystem 179
6.2 ExpressionsfromtheKineticTheoryofGases 181
6.2.1 TheMeanFreePath 181
6.2.2 CollisionFrequencyonaPlaneSurface 182
6.3 VariousApplications 183
6.3.1 RateofOxidation 183
6.3.2 EvaporationProcesses 184
6.3.3 ProcessesinthePresenceofanInertGas 186
6.3.4 Outgassing 187
x CONTENTS
6.4 Throughput,ConductanceandPumpingSpeed 188
6.4.1 ViscousFlow 189
6.4.2 MolecularFlow 190
6.4.3 TheTransitionRegion 191
6.4.4 MolecularFlow,ShortTubes 191
6.5 ForevacuumPumps 194
6.5.1 TheOilSealedRotaryVanePump 194
6.5.2 TheRotaryPistonPump 197
6.5.3 OtherForevacuumandMedium-PressurePumps 197
6.6 High-VacuumPumps 197
6.6.1 TheOilDiffusionPump 197
6.6.2 VapourBoosterPumps 200
6.6.3 TurbomolecularPumps 200
6.6.4 TheIonPump 201
6.7 EvacuationTimeandChamberMaterials 201
6.7.1 EvacuationTime 201
6.7.2 TheSuitablePumpCombination 201
6.7.3 MaterialsandOutgassing 202
6.8 FlangeFittings 204
6.8.1 TheFlangeandtheO-Ring 204
6.8.2 SmallFlangeFittings 206
6.8.3 Rotatable,Collar,andClampingFlanges 207
6.8.4 ConFlat(CF)Flanges 208
6.9 Valves 209
6.9.1 High-VacuumValves 209
6.9.2 ForevacuumandGasAdmittanceValves 210
6.10 Feedthroughs 211
6.10.1 PackingGlands 211
6.10.2 ElectricLeads 212
6.10.3 Windows 213
6.11 PressureandVacuumGauges 214
6.11.1 TheMercuryManometer 214
6.11.2 TheMcLeodManometer(H.G.McLeod,1874) 215
6.11.3 DiaphragmManometers 217
6.11.4 ThePiraniandtheThermoelectricGauge
(M.Pirani,1880–1968) 217
6.11.5 Hot-CathodeIonizationGauge 218
6.11.6 Penning,orCold-CathodeIonisation
Gauge(F.M.Penning,1894–1953) 219
CONTENTS xi
6.12 LeakDetectionandMending 220
6.12.1 PreliminaryTestingofComponents 220
6.12.2 ANoteonCleanliness 221
6.12.3 LeakTesting,FirstStep 221
6.12.4 LeakRates 222
6.12.5 LeakHunting 222
6.12.6 Mending 225
References 226
7 HighTemperatureFurnacesandThermobalances 227
Preamble 228
7.1 AimandScope 228
7.1.1 HighTemperatureFurnaces 228
7.1.2 Thermobalances 229
7.2 GeneralDesignPrinciples 229
7.2.1 GraphiteHeatingElements 229
7.2.2 Current,VoltageandTerminals 230
7.2.3 ObtainingaZoneofUniformTemperature 230
7.2.4 MaterialsandWaterCooling 233
7.2.5 PositionsofFurnaceandBalance 234
7.3 SpecificFurnace/ThermobalanceDesigns 236
7.3.1 TheBellJarType:Beljara 236
7.3.2 MovableFurnace:Octopus 240
7.3.3 TheJarUpsideDown:Maxine 244
7.3.4 FrontDoor:Versatilie 249
7.4 NotesonWindowsandBalances 256
7.4.1 WindowsforOpticalPyrometry 256
7.4.2 BalancesforThermogravimetry 260
7.4.3 AdjustingtothePyrometerTarget 261
7.5 Non-GraphiteHeatingElements 262
7.6 ConcludingRemarks 265
References 266
8 TheSummingUp 267
Preamble 268
8.1 EquilibriumGasPressures(I):(cid:3)10(cid:4)4–10(cid:4)1mbar 268
8.1.1 AnIntroduction 268
8.1.2 KnudsenEffusion 268
8.1.3 TheClausingFactor 270