Post on 01-Oct-2020
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Eskisehir Technical University ‐ Dr. Umut Savacı
MLZ 229 MATERIALS CHARACTERISATION TECHNIQUES:
THERMAL ANALYSIS (TA)
Eskisehir Technical University ‐ Dr. Umut Savacı
Eskisehir Technical University ‐ Dr. Umut Savacı
CHARACTERISATION TECHNIQUES
Non-Microscobic Tech.Microscobic Tech.
Light Microscopy
Scanning Electron Micr.
Transmission Electron Micr.
Other Tech.
Thermal Analysis
X-ray Diffraction
Spectroscopic Techniques
Other Tech.
Eskisehir Technical University ‐ Dr. Umut Savacı
TRUSTING BLACK BOX
Working PrinciplesOperationComments
Why You need to study?
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Eskisehir Technical University ‐ Dr. Umut Savacı
What do you understand from«THERMAL ANALYSIS» ?
Temperature ?
Sample ?
Heat ?
Melting ?
Furnace ?
Cooling ? Thermometer ?
Thermal Conductivity ?
Bread ???
Chocolate ???
Thermocouple ?
Pyrometer ? Heat capacity?
Eskisehir Technical University ‐ Dr. Umut Savacı
HEAT AND SPECIMEN INTERACTION
Volume ChangeWeight Change
Specimen
New Products
Eskisehir Technical University ‐ Dr. Umut Savacı
Any of these events or reactions
DTA/DSC
Phase Transformation
Volume ChangeWeight Change
Specimen
New ProductsH2O, CO, CO2, MxOy & etc
Loss
Oxidation
Gain
EvaporationLoss of HumidityLoss of Chemical WaterDecomposition (Carbonates)
Shrinkage Expansion
CrsytallisationGlass Transition
MeltingEndothermic Exothermic
TG Dilatometer
MSTG‐DTA TG‐DSC TG‐MS TG‐DTA‐MS
Eskisehir Technical University ‐ Dr. Umut Savacı
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Eskisehir Technical University ‐ Dr. Umut Savacı
CLASSIFICATION &APPLICATION GUIDE
Eskisehir Technical University ‐ Dr. Umut Savacı
Crystal Structure
Processing
Properties
Performance
Characterisaton
TA-PERFORMANCE-PROPERTIES RELATIONSHIP
Phase Transformation T.Crsytallisation T.
Glass Transition T.Thermal Exp. Coeff.
Decomposition T.Melting T.
Moisture ContentPurity Content
Thermal Stability
Chemical Stability
Reaction T.
Phase ContentGlasses do not melt at a sharply defined temperature, but soften over a temperatureinterval. This softening temperature is called as glass transition temperature
Eskisehir Technical University ‐ Dr. Umut Savacı
WHAT IS THERMAL ANALYSIS?
A group of techniques measuring the physical andchemical changes of a matter (material properties) asa function of temperature, time & atmosphere undera controlled temperature program
LEARNING OBJECTIVES?Know which TA techniques are appropriate to measure avariety of materials properties.Have some practical knowledge of how TA experiments arecarried out.Be able to interpret TA data in order to calculate sampleproperties.
Eskisehir Technical University ‐ Dr. Umut Savacı
History
8000 BC 8000 BC
3400 BC
19th CenturyControlled and quantitative analyses
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Eskisehir Technical University ‐ Dr. Umut Savacı
MATERIALS TO BE STUDIED
TA techniques are used in virtually every area ofmodern science & technologyCeramics & glassesCatalysisPolymeric materialsMetalic materialsBuilding materialsBiological materialsFood IndustryLiquids (limited)
Eskisehir Technical University ‐ Dr. Umut Savacı
WHERE IS THERMAL ANALYSIS USED?
(i) Research and development of new products:Development and selection of new materials,Performance and evaluation of existing materials
Crystallinity, specific heat, expansion, shrinkage(ii)Quality control & assurance: FingerprintingTroubleshooting, Monitoring, Purity and Certification
(iii) Reverse Engineering; TA results allow toconclude chemical and phase composition andmanufacturing history of Bronze Age pottery
Eskisehir Technical University ‐ Dr. Umut Savacı
Any of these events or reactions
DTA/DSC
Phase Transformation
Volume ChangeWeight Change
Specimen
New ProductsH2O, CO, CO2, MxOy & etc
Loss
Oxidation
Gain
EvaporationLoss of HumidityLoss of Chemical WaterDecomposition (Carbonates)
Shrinkage Expansion
CrystallisationGlass Transition
MeltingEndothermic Exothermic
TG Dilatometer
MSTG‐DTA TG‐DSC TG‐MS TG‐DTA‐MS
Eskisehir Technical University ‐ Dr. Umut Savacı
Phase Transformation
Solid SolidSolid LiquidSolid GasLiquidGas
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Eskisehir Technical University ‐ Dr. Umut Savacı
PROPERTIES TO BE STUDIED:1.PHASE TRANSFORMATIONS
DISPLACIVE PHASE TRANSFORMATIONSNo chemical bond broken
Eskisehir Technical University ‐ Dr. Umut Savacı
PROPERTIES TO BE STUDIED:1.PHASE TRANSFORMATIONS
DISPLACIVE PHASE TRANSFORMATIONS
Eskisehir Technical University ‐ Dr. Umut Savacı
PHASE TRANSFORMATIONSRECONSTRUCTIVE PHASE TRANSFORMATIONS
Chemical bonds are broken and reconstructed
Eskisehir Technical University ‐ Dr. Umut Savacı
PHASE TRANSFORMATIONS
Diamond (C)
Quartz (SiO )2
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Eskisehir Technical University ‐ Dr. Umut Savacı
QUARTZ PHASE TRANSFORMATIONS
Eskisehir Technical University ‐ Dr. Umut Savacı
PHASE TRANSFORMATIONS
Silica have three different forms:Quartz, trydymite, crystoballite-quartz, -crystobalite and -tridymitetransformations are displacive (atomic positions do notchange much)However, quartz crystobalite tridymitetransformations are reconstructive (new crystal latticewill form and is very slow)Volume changes occur and cracks will form
PROPERTIES TO BE STUDIED
Eskisehir Technical University ‐ Dr. Umut Savacı
PHASE TRANSFORMATIONS
Eskisehir Technical University ‐ Dr. Umut Savacı
2. POSSIBLE REACTIONS
Physical Water Loss
Clay minerals can contain different ratios of physicalwater. Amount of water and the temperature of losscan give information about the mineral.
Will be lost around 100˚C
The amount of water depends on the particle sizeand mineral type
PROPERTIES TO BE STUDIED
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Eskisehir Technical University ‐ Dr. Umut Savacı
POSSIBLE REACTIONS
Physical Water Loss
Type of mineral Percentage weight lost (%)
Cornish china clay 1.2Stourbridge fire clay 3.8Brick clay 2.0Ball clay (Dorset) 5.7Bonding clay (Scottish) 7.4Eureka halloysite 6.3Wyoming bentonite (Montmorillonite) 14.2
Eskisehir Technical University ‐ Dr. Umut Savacı
POSSIBLE REACTIONS
Chemical Water LossAs the temperature rise the crystal water will be lostslowlyFor exam.: kaolinite will loose its crystal water at420˚C but it will take months.However, at 550˚C it will only take half an hrBoth the chemical and physical water requires heatto be lost
Eskisehir Technical University ‐ Dr. Umut Savacı
POSSIBLE REACTIONSChemical Water Loss
Mineral Chemical Formula Temp. of rapid decomposition (oC)
Percentage water lost
Kaolinite Al2O3.2SiO2.2H2O 585 14.1Halloysite Al2O3.2SiO2.2H2O 558 14.1Montmorillonite Al2O3.4SiO2.H2O (ideal) 678 5.0Muscovite mica K2O.3Al2O3.6SiO2.2H2O 856 4.5Hydrous mica As above but less alkali
& more water550 upwards 6.0-10.0
Gibbsite Al(OH)3 325 34.6Goethite FeO(OH) 350 10.1
Eskisehir Technical University ‐ Dr. Umut Savacı
POSSIBLE REACTIONS
Decomposition of sulphates and carbonatesIf the clay mineral contains sulphates andcarbonates, they decompose under heatCalcium carbonate (CaCO3, calcite) common mineralfound in clay and @ 880˚C it decomposes with 44 %weight lossMagnesium carbonate (MgCO3) decomposes @ 790˚CDolomite is a mixture of both ((Ca, Mg)CO3) andbehave like two different carbonates
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Eskisehir Technical University ‐ Dr. Umut Savacı
POSSIBLE REACTIONS
ORGANICSOrganic materials oxidized and lost from the mainmaterials between 200˚C and 1000˚C
Eskisehir Technical University ‐ Dr. Umut Savacı
Possible ReactionsMaterials may react with the surrounding atmosphere
Eskisehir Technical University ‐ Dr. Umut Savacı
Why Use Thermal Analysis Techniques?
to measure a property of interest, such as specific heat, latent heat or heat of reactionto fingerprint a particular material or substanceto assess the high-temperature stability ofmaterialsto detect phase transformationsfundamental studies of reaction kinetics
Eskisehir Technical University ‐ Dr. Umut Savacı
Common Types of Experimental Scans
Temperature scanIsothermal heat treatment
• The isothermal heat treatment is usually best suited to kinetic studies. It is useful to study things that happen far away from the equilibrium temperature and hence occur when we hold the temperature constant
• The temperature scan is generally more useful to examine thermodynamic properties. It is useful to study things that happen near to the equilibrium temperature and hence need us to ramp up from below the equilibrium temperature to above it in order for the transformation to occur.
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Eskisehir Technical University ‐ Dr. Umut Savacı
Properties Studied by Thermal AnalysisThere are a wide range of properties that may be studied, and each has an associatedtechnique which can be used:
• a) specific heat• b) thermal expansion• c) weight• d) flow stress• e) viscosity• f) elastic modulus and damping• g) evolved gases• h) phase changes and lattice parameter• Of course, you can measure just about any property as a function of temperature, i.e.
Electrical resistivity, magnetic permeability, thermoluminescence. But some techniques (those which have acquired acronyms) are commonly used and have developed specialised commercial instrumentation.
Eskisehir Technical University ‐ Dr. Umut Savacı
USE INTERNET WISELY!
Eskisehir Technical University ‐ Dr. Umut Savacı
CLASSIFICATION &APPLICATION GUIDE