Thermal Analysis: Methods, Principles, Applicaon

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Thermal Analysis: methods, principles, applica5onAndrey TarasovLecture on Thermal analysis26.16.2012Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.12

Main definitionsHeatHeat CapacityC Q/ΔT, [J/mol/K]Thermal conductivityλ a·Cp·ρ [J/s/m/K] [W/m/K]a – thermal diffusivity, m2/sAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.122

Defini5on of TAGroup of physical‐chemical methods which deal with studying materialsand processes under condi5ons of programmed changing's of thesurrounding temperature.Differential Heat equationMain Thermo-physical properties of onThermal conduc5vityλ(T) a·Cp(T)·ρ(T)Thermal linearexpansionε 1/r*(dr/dT)%/KDILEnthalpydQ/dt m·Cp·(dT/dt)J/gDSCWeight/Composi5on/Conversionα (mo-mi)/mo%TGUnitW/(m*K)MethodLFAr, φ - polar coordinatesz - applicateλ – Thermal conductivity , J/(cm*s*K)Cp – Thermal capacity, J/(g*K)ρ– density, g/(cm3)Q – heat of the process (reaction)α – degree of conversionAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.12a – thermal diffusivity, cm2/s3

Thermal conductivity, thermal diffusivityAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.124

Laser Flash Method (LFA)λ(T) a·Cp(T)·ρ(T)Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.125

Dilatometry (DIL)ε 1/r*(dr/dT)ε – thermal expansion coefficientr – sample lengthDIL Measurement Information Linear thermal expansion Determination of coefficient of thermal expansion Sintering temperatures Softening points Phase transitionsSiN thermal shrinkageAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.125

Basic Principles and TerminologyPrinciple of combined thermocoupleRegistra5on the temperature of the object and temperature differencebetween sample and referenceConsequenceDepending on the engineering design, measuring cell construc5on and the wayof data representa5on, variety of methods has been arisen: DTG, DTA, DSC, STAetc.Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.126

Basic Principles and TerminologyDSC-TGDSC ‐ (Differen5al Scanning Calorimetry):Voltage to keep ΔT TS‐TR 0 vs. TRDTA (Reverse Differen5al Thermal Analysis) TGdt/dT vs. TIn ACThermoLabTA – (Thermal analysis )TS vs. tTG – (Thermogravimetric analysis)Δm vs. TDTA ‐ (Differen5al Thermal Analysis)ΔT TS‐TR vs. TDTA-TGCalvet-DSCCalvet TADDTA ‐ (Deriva5ve DTA)dΔT/dt vs. TSTA – Simultaneous Thermal Analysis: TG – DSC ; EVA – Evolved gas analysis: MS, FTIR, GCHyphenated techniquesAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.127

Basic Principles and TerminologyThermocouplesTypeTemperature range, KComposi onTminTmaxOutput voltage(0 C), mVTCu /constantan367020JFe/constantan7087034Echromel /constantan‐97045Kchromel /alumel220127041SPt/PtRh (10)270157013RPt/PtRh 120039Constantan - 58% Cu, 42% NiChromel – 89% Ni, 10% Cr, 1%FeCu/Constantandisk sensor onSi(X) waffer.µ sensorAlumel – 94% Ni, 2% Al, 1,5% Si, 2,5 % MnNicrosil/Nisil – Ni, Cr, Silicon/Ni, SiliconCuNi disk sensoron Ag plate.Pt-PtRh(10)diskshapedthermocoupleτ sensorAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.128

Basic Principles and TerminologyTGDSC (Heat flux)SMP g ((mSC mS mA) - (VSC VS VA) ρgas) gFBSMP - Measurement signalFB - Buoyancy force , f(T)mA - Mass of adsorbed gas, f(T)mSC - Mass of sample containermS - Mass of sample , f(T)VA - Volume of adsorbed gas , f(T)VSC - Volume of sample containerVS - Volume of sample, f(T)STAρgas - Density of gas, f(T)Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.129

Basic Principles and TerminologysensorreferencesensorsampleAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1210

General Theory (Heat equation for inert material)Temperature lagr, φ - polar coordinatesb – heating rate, K/mina -Temperature conductivity coefficient, cm2/sλ – Thermal conductivity , J/(cm*s*K)Cp – Thermal capacity, J/(g*K)ρ– density, g/(cm3)Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1211

General Theory (Temperature field in active sample)ExothermicΔQ 0, ΔH 0Temperature and reac5on extent field for exothermic processesEndothermicΔQ 0, ΔH 0Temperature and reac5on extent field for endothermic processAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1212

General TheoryDSCTGPb(S) Pb(L), ΔH 298 5 kJ/molSetup baseline (zero line)CuO(S) H2(g) CuO(s) H2O(g) , ΔH 298 -86 kJ/molBlank measurement (zero line)Baseline interpolatedEndothermic peakShift of the baseline could appear due tochange in thermal resistance of the setup.Position is depending on measuring-history.Measurements may have a significantchange in weight due to changes in gasdensity and viscosity.Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1213

General TheoryHeat balanceΛ(T) – heat transfer coefficientc – measuring cell heat capacityM – mass of the measuring cellΔT – generated temperature differenceα ‐ normalized conversionHeat of the process is determined as follows:S – available surface for heat exchangem – sample massΔT – generated temperature differenceK(T) – instrument constantΛrad – radia5on energy between oven and sampleλs – sample thermal conduc5vityA – DSC peak areaAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1214

General TheoryCalibration StandardsStandardMel ng Point, CHeat of Fusion, J/gIn156,6‐ ,8‐104,6Au1064,2Unalloeyd ,3Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1215

General Theory (DTA equation)φ – hea/ng rate, K/min1.2.3.4.5.6.Experimental DTA curveDTA curve corrected to heat transfer condi5onsTrue baseline of DTA curveInterpolated baseline;Experimental baseline;Experimental baseline aler process, shiled because ofthermal capacity changes.Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1216

General TheoryDSC ArtifactsAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1217

General Theory3 major aspects of correct DSC measurement:BaselineGradient TCalibration, KDTA, τAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1218

General TheoryBaseline definition.1 Linear BaselineIt should be used for measurements in which no significant Cpchanges are observed during melting. The linear baseline isgenerally used.2Sigmoidal BaselineThis baseline is used when the melting process isaccompanied by a notable Cp change.3Tangential Area-Proportional BaselineThis baseline is used when the melting process isaccompanied by a notable Cp change and a slopingbaseline exists.Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1219

General TheoryAu(S) Au(L), ΔH 298 12,6 kJ/molsigmoidalIn(S) In(L), ΔH 298 3.3 kJ/mollinearCuO/ZnAl2O4 H2 Cu/ZnAl2O4 H2OtangentialAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1220

General TheoryDSC peak CorrectionIn(S) In(L), ΔH 298 3.3 kJ/molIssues by uncorrected data1.2.Temperature on the peak point does notcorrespond to the melting temperature (but fromphysical point of view the sample temperatureshould be equal to melting point)After peak maximum the signal diminishes slowly.(Although it is known that the sample is completelymolten)Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1221

General TheoryBad thermal contactLong melting timeBroad, low peakGood Thermal contactShort melting timeSharp peakThe slope of the peak left side is depended on thermal resistancePeak area is the same and equals melting enthalpy.Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1222

General Theoryf(t) – evolved heatF(t) – measured signalg(t) – response functiong(t) exp(-t/τ)small τbig τThe peak right side is depended on instrumenttime constant.τ1 τ2Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1223

General TheoryDSC peak CorrectionOriginal signalTime constant correctionFull correctionAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1224

General TheoryThe proper5es of the system «sample‐sensor» strongly influence the experimental TA curvesFeatures of TA Setupa)Reac5on Atmosphereb)Size and shape of the ovenc)Sample holder materiald)Sample holder geometrye)Hea5ng ratef)Thermocouple (wire diameter)g)Thermocouple loca5onh)Response 5meCharacteris5cs of the samplea)b)c)d)e)f)g)h)Par5cle sizeThermal conduc5vityThermal capacityPacking density of par5cles (powder, pill, tablet)Sample expansion and shrinkingSample massInert fillerDegree of crystallinityInforma5on obtained depends on procedureNot fundamental propertyAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1225

Influence of external gas flowSetup: Netzsch – STA JupiterСаС2О4 nН2О СаС2О4 nН2О СаСО3 1/2 СО2 СаО СО21 stage2 stage3 stageDehydration of CaC2O4·nH2O in an open crucible in a dry airflow (red curve) and in a static atmosphere (green curve).Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1226

Influence of external atmosphereSetup: Netzsch – STA JupiterTGDr. Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1227

Influence of external atmospherek1M CuxZn1-xDSC‐TG sample holder,Sample weight: 10mgVacuum 10-4 barAr, 100ml/minAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1228

Influence of sample massk1Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1229

Influence of heating rateIndependent processesEa1 Ea2Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1230

Influence of heating rateSubsequent processesLa(OH)3 LaOOH H2OLaOOH La2O3 H2OAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1231

Influence of heating rateCompetitive process processesEa1 Ea2Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1232

Influence of the pan materialSetup: Netzsch – STA JupiterAlPtAl2O3NiCuQuartzPyrolisis of Fluoropolymer: TFE‐VDF, ‐{C2F4}n ‐ {C2H2F2}m , F42 – in Al an Au pansin Alin Au10Kpm, Ar, 100ml/minAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1233

Strong exothermic reactionsSetup: Netzsch – STA JupiterInterac5on of Ta and Nb with Fluoropolymer: TFE‐VDF, ‐{C2F4}n ‐ {C2H2F2}m ‐, F42with A. Alikhanjan, and I. Arkhangelsky (2009)ΔMTa-F42-strong heat evolution, narrow ΔT-2 stages by interaction-sharp weight loss due to reaction betweentwo solid interfaces.Mass loss: reflects the available metalsurface which is in contact with polymer.Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1234

Strong exothermic reactionsSetup: Netzsch – STA JupiterExothermicEndothermic (due to water traces)Two effects coinsides resulting in endothermic effect.Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1235

Measurement in inert. Is the system oxygen free?Setup: Netzsch – STA JupiterCuC2O4 0.5H2O Cu 2CO2Cu 1/2O2 CuOO2 traces of 0.25ppmDSC‐TG sample holder,Al2O3 pan, Ar 100ml/minSample: CuC2O4 0.5H2OWeight: 9.1mgAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1236

Measurement in inert. Is the system oxygen free?Setup: Netzsch – STA JupiterDSC‐TG sample holder,Al2O3 pan, Ar 100ml/minSample: Ni/MgAl2O4Weight: 14.1mgNi 1/2O2 NiO@RT O2 traces of 1.7ppmAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1237

Measurement in inert. Is the system oxygen free?Setup: Rubotherm – MSBCuC2O4 0.5H2O Cu 2CO2Cu 1/2O2 CuOTG sample holder,Al2O3 pan, Ar 250ml/minSample: CuC2O4 0.5H2OWeight: 301.8mgO2 traces of 7ppmAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1238

Determina5on of crystallinity degreeTFE‐VDF, ‐{C2F4}n ‐ {C2H2F2}m ‐, F42Χ ΔНf/ΔHfoX-degree of crystallinityΔHfo – enthalpy of polymer with 100% degree of crystallinityΔHfo 99.3J/gAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1239

TA-MS Coupling systemsSkimmer coupling systemAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1240

TA-MS Coupling systemsCapillary coupling systemAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1241

Main Problems of TA-MS coupling system Pressure reduction103mbar 10-5mbar Condensation and secondary reactionsUnfalsified gas transferDifferent viscosity – Demixing Attribution of a fragment to a chemical processPyrolysis or evaporationMS fragmentation or sample behavior Overlapping of thermal processeshydrolysis and oxidation due to rest water andoxygen background in the feed.Disadvantages: shock sensitive, no direct MS inlet.Kaiserberger (1999)Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1242

(PulseTA ) Adsorption of Methanol on β-AlF3Sample: β‐ AlF3Sample weight: 43.81 mgΔm 0.15mg,N2 ‐ 70ml/minM. Feist et. al. 2010Determining Lewis acidityTA-MS curves for a PulseTA experiment on pretreated (2 h, 250 C; vacuum)Andrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1243

(PulseTA ) Titration of Ni surface with O2** Assuming O/Ni 2, dNi 9nm in agreement with TEMSample: Ni/MgAl2O4Sample weight: 30.8 mgΔm 1.14mg,Ar ‐ 100ml/minµO(chemisorbed)/µNi(reduced) 0.22PTA curves of NiO/MgAl2O4 after reduction, isothermal at 45 C with O2 injections,Interupted by a H2 pulseAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1244

Resources J. Sestak, Thermophysical properties of solids (Academia, Prague, 1984) G. Höhne, W. Hemminger, H.-J.Flammersheim, Differential Scanning Calorimetry(Springer, Berlin, 1996) E. Moukhina, J. Therm Anal. Calorim. (2012) 109: 1203-1214 http://www.netzsch.comAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.1245

Acknowledgments Dr. Elena Moukhina, Netzsch Gerätebau GmbH, Selb Dr. Jan Hanss, Netzsch Gerätebau GmbH, Selb Dr. Michael Feist, HU Berlin Prof. Igor Arkhangelsky, MSU Moscow Dr. Alexander Dunaev, MSU MoscowthermalAndrey Tarasov, Thermal analysis, Lecture series heterogeneous catalysis, FHI MPG, 26.10.12analysis46

Thank you!47

(Although it is known that the sample is completely molten) 21 . Bad thermal contact Long melting time Broad, low peak Good Thermal contact Short melting time Sharp peak The slope of the peak left side is depended on thermal resistance Peak area is the same and equals melting enthalpy.

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