Thermally Sprayed Coatings and their Characterization ... · and their Characterization Techniques...
Transcript of Thermally Sprayed Coatings and their Characterization ... · and their Characterization Techniques...
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Thermally Sprayed CoatingsThermally Sprayed Coatingsand their Characterizationand their Characterization
TechniquesTechniques
EMPA-ThunEMPA-Thun
St. Siegmann,St. Siegmann,O. Brandt, M. O. Brandt, M. AeberhardAeberhard
CEAC Summer Workshop 1999:CEAC Summer Workshop 1999:FunctionalizedFunctionalized Surfaces: Application and Analytical Tools Surfaces: Application and Analytical Tools
July 5-6, 1999July 5-6, 1999----------------------------------------------------------------------------------------
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Thermally Sprayed Coatings andThermally Sprayed Coatings andtheir Characterization Techniquestheir Characterization Techniques
1. Thermal Spraying �Coating Morphology 2. Characterization Techniques:
2.1 Destructive Test Methods:- Coating Adhesion- Metallographical Preparation- Hardness Testing- Chemical Composition (e.g. GDOS)- Wear Testing- Corrosion Testing
2.2 Non-destructive Test Methods:- Coating Thickness Measurements- Ultrasonic Testing- Thermal Imaging
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History of Thermal Spraying:
Dr. Max U. SchoopBorn: April 10, 1870 in Frauenfeld (TG)Deceased: February 20, 1956 in Zürich(Drawing from 1920)
from: Tagungsunterlagen zum 3. Kolloquium über Hochgeschw.-Flammspritzen, Dr. K. Kirner
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Classification of Thermal Spraying(according EN 657)
Thermal spraying
Thermalsprayingby liquid
Thermal spraying by gas
Thermal spraying byelectric gas discharge
Molten bathspraying
Flamespraying
Detonationspraying
High velocityflame spraying
Powder flamespraying
Wire flamespraying
Arc spraying Plasma spraying
Plasmaspraying in air
Liquid stabilisedplasma spraying
Plasma sprayingin chambers
Laser spraying
Thermalsprayingby beam
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Different Thermal Spray Torches:
from: Stan Grainger, "Funktionelle Beschichtungen in Konstruktion und Anwendung"
Flame Spraying
Detonation GunSpraying
High VelocityOxygen Fuel
Spraying Plasma Spraying
Electric Arc Spraying
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Thermal Spraying by Principle:molten droplets
"clamping"
substrate
"local alloying"
voids
heat powder+ =
v
time
Temperature
RT
T melting
T substrate
T boiling
dT/dt = 10 K/s6
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Thermal Spraying in „Reality“:Powder Splats Coating / Substrate
Ref 1: Edward J. Kubel Jr. in Adv. Mat. & Proc. 12/90Ref 2: R.C. Dykhuizen in Journ. of Therm. Spr. Techn. Vol 3, No. 4 (94)Ref 3: M. Vardelle et al. in Journ. of Therm. Spr. Techn. Vol 4, No. 1 (95)
1) 2)
3)
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Thermally Sprayed Cr2O3-Coatings (created by different processes)
flame sprayed plasma sprayed HVOF sprayed
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2. Characterization Techniques
2.1 Destructive Test Methods
2.1.1. Coating Adhesion (EN 582, ISO/DIS 14916)
2.1.2. Metallographical Preparation for LM, SEM, etc.
2.1.3. Hardness Testing
2.1.4. Chemical Analysis (e.g. GDOS, and others)
2.1.5. Wear Testing
2.1.6. Corrosion Testing
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Tensile testingmachine :Epprecht: 250 kN
Tensile AdhesiveStrength Test(EN 582, ISO/DIS 14916)
Frame for glueing 5 samples(left: empty, right: with samples)
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MetallographicalPreparationInvestigation of:Coating thickness, coatingmorphology (structure, phases,porosity), bonding to substrate,micro hardness
Steps:1. Sectioning2. Embedding (organic binder, event. vacuum infiltration)3. Grinding (e.g. SiC 180 to 1200)4. Polishing (6, 3, 1, 1/4 µm)5. Cleaning6. Event. sputtering for interference layer contrast (e.g. ZnSe, ZnTe)7. Electrolytic -, chemical etching8. Investigation (LM, SEM) � Interpretation
from: DVS 2310-1 Merkblatt
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Hydroxyapatite Coatings forBiomedical Applications:
atmosphericplasma sprayed
vacuumplasma sprayed
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Hardness Testing� ISO 4516 Metallic and related coatings; Vickers and Knoop
microhardness tests� ISO 6506 Metallic materials; Hardness test; Brinell test� ISO 6507-1 Metallic materials - Vickers hardness test - Part 1:
Test method� ISO 6507-2 Metallic materials - Vickers hardness test - Part 2:
Verification of testing machines� ISO 6507-3 Metallic materials - Vickers hardness test - Part 3:
Calibration of reference blocks� ISO 6508 Metallic materials; Hardness test; Rockwell test
(scales A - B - C - D - E - F - G - H - K)
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Example of Microhardness Teston a Thermally Sprayed Coating
HV � 0.1891 x F/d2
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Chemical Analysis
� X-Ray Fluorescence Analysis (XRF)� Glow Discharge Optical Spectroscopy (GDOS)� Mass Spectrometry (MS)� Energy Dispersive X-Ray Analysis (EDX)� Electron Probe Micro Analysis (EPMA)� Transmission Electron Microscopy (TEM)� and many others ...
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Glow Discharge Optical EmissionSpectroscopy GDO(E)S
Glow Discharge ...
...Optical Emission Spectroscopy
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I
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0.1 nm
1 nm
10 nm
100 nm
1 µm
1.0 ppm 100 ppm 1% 100%
10 µm
Surface
Bulk
Concentration
Info
rmat
ion
Dep
th
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Comparison of Different MethodsEigenschaften AES SIMS ESCA ESMA SNMS GDOS
erfassbarerTiefenbereich in nm
1 - 100ohne
Zerstäubung
0,3 - 103
ohneZerstäubung
1 - 100ohne
Zerstäubung
Querschliff 0,5 - 104 1 - 105
Informationstiefe innm
1 - 6 0,5 - 1 0,5 - 10 1000 1 - 2 mitZerstäubung
1 - 100Tiefenauflösung in% der abgetragenen
Tiefe
2 nmohne
Zerstäubung
10 nmmit
Zerstäubung
0,5 nmohne
Zerstäubung
0,1 nm 10 7 - 12
TiefenprofilanalysetechnischerSchichten
1 - 2 µm mitZerstäubung;
oderQuerschliff
> 10 µm mitZerstäubung;Querschliff
1 µm mitZerstäubung;Querschliff
Querschliff Zerstäubung indie Tiefe5 - 10 µm
Zerstäubung indie Tiefe
40 - 150 µmmater. abh.
laterale Auflösung 0,2 µm 0,3 µm 200 µm 1 µm 20 µm 2,5 - 8 mmSimultananalyse keine keine keine keine keine max. alle
Elementetypische
Nachweisgrenzenin %
element-abhängig
0,1 - 5
teilweise bis10-4
0,1 - 1 0,1 - 10-3 0,1 - 10-4 10-2 - 10-4
Nachweis leichterElemente
> 0,1 atom %und Z � 3
alleeinschliesslich
H
alle ohne H nicht unter0,1 %
alleeinschliesslich
H
alleeinschliesslich
HQuantitative
Messungnicht sehr
genaunur in
homogenerMatrix
� 5 %verschiedene
Elemente
leichteElemente
schwierig bisunmög.
Quantifizierung Quantifizierung
AES = Auger Electron SpectroscopySIMS = Secondary Ion Mass SpectroscopyESCA = Electron Spectroscopy for Chemical AnalysisESMA = Elektronenstrahl Mikroanalyse = EPMA = Electron Microprobe AnalysisSNMS = Secondary Neutral Mass SpectroscopyGDOS = Glowdischarge Optical Spectroscopy
Ref. H. Böhm, Oberflächen Werkstoffe, Nr.4/94
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• Quality control for different coating systems(e.g. car industry)
• Galvanic coatings• Thin films (Semiconductor industry)• Paintings• Thermal Spraying• Diffusion zones• and many others ...
Typical Applications of GDOS:
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05
1015202530354045
Intensity (Volt)
Con
cent
ratio
n (%
)
AluminumCast ironSteelBrass
Quantitative Calibration of SiContent in Different Matrices
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TiN + TiCN on Steel
0
10
20
30
40
50
60
70
80
90
100
0.0 2.0 4.0 6.0 8.0 10.0 12.0
Tiefe in µm
Kon
zent
ratio
n in
%G
Ti
Steel
C
N Fe
Ti N
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Paintings on Tinplate
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GDOES... is a quantitative chemistry analysis method... for conductive and non conductive materials (RF)... for high concentration range (ppm ...100 %)... offers good resolution in depth (nm)... offers good integration in lateral size (spot diameter)... offers fast response (1 ... 10 µm/Min.)... up/down to 100‘s of microns... analysis of all elements (H...U) simultaneously... keeps substrate temperature low... needs no wet chemistry
Advantages
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Some Wear Testing StandardsASTM G 32: Test Method for Cavitation Erosion Using Vibratory
Apparatus (1992)
ASTM G 65: Test Method for Measuring Abrasion Using the DrySand/Rubber Wheel Apparatus (1994)
ASTM G 73: Liquid Impingement Erosion Testing (1993)
ASTM G 75: Test Method for Determination of Slurry Abrasivity(Miller Number) and Slurry Abrasion Response ofMaterials (SAR Number) (1995)
ASTM G 76: Conducting Erosion Tests by Solid Particle ImpingementUsing Gas Jets (1995)
ASTM G 99: Test Method for Wear Testing with a Pin-on-DiskApparatus (1995)
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aus: DIN 50320 Verschleiss; Begriffe, Systemanalyse von Verschleissvorgängen, Gliederung des Verschleissgebietes
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ASTM G 32 - 92:Test Method forCavitationErosion UsingVibratoryApparatus
Bestimmung derKavitations-erosion anvibrierendenProben
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Test Method for MeasuringAbrasion Using the DrySand/Rubber WheelApparatus
Richtlinien für dieDurchführung vonAbriebversuchen mitTrockensand undrotierendem Gummirad
ASTM G 65 - 94:
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Determination of SlurryAbrasivity (Miller Number)and Slurry AbrasionResponse of Materials(SAR Number)
Bestimmung derSchleifwirkung vonSchlamm nach demNummernsystem vonMiller
ASTM G 75 - 95:
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100 1000 100000,1
1
10
100Volumetricmaterial losstestedaccording toASTM G 75as a functionof materialshardness
Ref. WF-Project, O. Brandt, St. Siegmann
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Bedienpult
PulverförderAbsetzbecken
Erosionskammer
HorizontaleFührungs-schiene
Höhen-verstellungvergl.Abb. 6
Proben-halterungmit Ver-formungs-einrichtungAbb. 8
VertikaleFührung
PneumatischerSchliesser
MischkopfAbb.2
Hochdruck-pumpen-anschluss
Erosion Test Equipment
Ref. L. Kirchhoff, O. Brandt
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ASTM G 99: Pin-on-Disk Tribometer
Rotation speed: 0.03 to 500 rpmForces: 1 to 60 NStandard loads: 1, 2, 5, 10 NDisk dimensions: r = 60 mm,
h = 15 mm
(compatible with DIN 50324)
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Some Technical Corrosion Tests
prEN 4437: Test Method of Salt Spray(Fog) Testing
EN ISO 6988: Sulfur dioxide test with generalcondensation of moisture
ASTM B 368: Acetic Acid-Salt Spray (Fog)Testing (CASS Test)
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CorrosionTesting
Fig: O. Brandt
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Results from Corrosion Tests
Same coating material:porous (atmospheric
sprayed) and showinginterface corrosion
dense (vacuum plasmasprayed)
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2.2. Non-destructive Test Methods
2.2.1. Coating Thickness Measurements
2.2.2. Chemical Composition (see also 2.1.4)
2.2.3. Ultrasonic Testing
2.2.4. Thermal Imageing
2. Characterization Techniques
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Standards for Coating Thickness Measurements1. ENV 1071-2 Determination of coating thickness by the cap grinding method2. ISO 1463 Measurement of coating thickness; Microscopical method3. ISO 2064 Definitions and conventions concerning the measurement of thickness4. ISO 2177 Measurement of coating thickness; Coulometric method by anodic
dissolution5. ISO 2178 Measurement of coating thickness; Magnetic method6. DVS 2303-1 Non-destructive testing of thermally sprayed coatings, thickness
measurements7. ISO 2360 Measurement of coating thickness; Eddy current method8. ISO 2808 Paints and varnishes - Determination of film thickness9. ISO 3497 Measurement of coating thickness; X-ray spectrometric methods
10. ISO 3543 Measurement of thickness; Beta backscatter method11. ISO 3868 Measurement of coating thicknesses; Fizeau multiple-beam
interferometry method; Mehrstrahlinterferometer-Methode nach Fizeau12. ISO 3882 Review of methods of measurement of thickness13. ISO 4518 Measurement of coating thickness; Profilometric method14. ISO 9220 Measurement of coating thickness; scanning electron
microscope method
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Ultrasonic Testing on Coatings(by principle)
from: Krautkrämer, Zerstörungsfreie Werkstoffprüfung mit Ultraschall, Einführung in die Grundlagen
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Ultrasonic Picture of Coatingand Adhesion Defects
Ultrasonic picture(from back side)
Optical picture(from top side)
corrosion
roughnessdefect
metallicinclusions
ceramic groundlayer
Gradient:metal /ceramic
substrate
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Ref. DACS / IBF
Thermal Imagingon ThermallySprayedCoatings(by principle)
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Investigation by Thermal Imaging
Ref. DACS / IBFRef. EMPA
Optical picture Thermographic picture
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Conclusions: Characterization
Many standardized test methods available
• for coating development
• for coating quality assurance
• for characterizing coating failure
but still needsbetter predictability of coating reliability
Research:as much as
possible
Industry:as much asnecessary