Advanced Thermal Barrier Coatings for Operation in High ......VOLVO AERO C HROMALLOY ICP Thermal...
Transcript of Advanced Thermal Barrier Coatings for Operation in High ......VOLVO AERO C HROMALLOY ICP Thermal...
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Advanced Thermal Barrier Coatings forOperation in High Hydrogen Content Gas Turbines
Christopher Weyant, Sanjay SampathCenter for Thermal Spray Research, Stony Brook University
University Turbine Systems Research WorkshopOctober 20, 2010
Research supported by:DOE NETL UTSR
DOE Office of Fossil Research STTR with Plasma Technology Inc.
AFRL, NSFConsortium on Thermal Spray Technology
Contributions from faculty colleagues, post-docs, students, national and international
collaborators is acknowledged.
Thermal Conductivity
Velocity (scaled)20 40 60 80 100
Te
mp
era
ture
(sc
ale
d)
20
40
60
80
100
Consortium is operated by the Center for Thermal Spray Research at Stony Brook University
VOLVO
AERO
CHROMALLOY
ICP
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Thermal Barrier Coatings in Hydrogen-Fired IGCC Turbines
- Increased mass flow of syngas fuel- Increased heat transfer from water vapor- Impact of water vapor on oxidation- Contaminants
- Material requirements and selection- Processing impacts on microstructure and properties- Iterative coating design and testing- Industry feedback and knowledge transfer
Courtesy of GE
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Degradation in IGCC Gas Turbine TBCs
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Proposed IGCC Coating Architecture
(Rene 80 or CMSX4)
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Overall UTSR Program Approach
CoNiCrAlY NiCrAlY
Advanced Thermal Spray TBCs for IGCC Turbine Systems
Top CoatBond Coat
Processing Effects on Microstructure
(HVOF/LPPS/Anneal)
Materials: MCrAlYM = Ni, Co, Si, Hf, La
Property Evaluation:Oxidation behavior in high temperature water vapor
Processing Effects on Microstructure
(APS)
Materials: YSZ, Gd2Zr2O7
Property Evaluation: Thermal conductivity, sintering, compliance,
erosion, thermal expansion
System Level
Rig Testing: Thermal gradient exposure with
water vapor
Property Evaluation: Bond coat oxidation, through-thickness residual stress
and composition, erosion
Isothermal Exposures with ash deposits
Isothermal Exposures in water vapor
Isothermal Exposures in water vapor
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Thermal spray is a complex process
Melting, quenching and consolidation in single process
Splat based build-up and state induced properties
High velocity &temperature
(melting/softening)
Impact &rapid solidification
Quenching, thermal stresses
SMALL-VOLUME STRUCTURES
20 m20 m
SMALL-VOLUME STRUCTURES
20 m20 m 20 m20 m
Layered and graded architectures through successive splat quenching
GradedPorosityIn ceramics
LayeredThickFilms
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Lee et al., J. Europ. Cer. Soc. 25(10):1705-1715 (2005).
Feedstock
Characteristics
Process
Variables
CoatingStructure
Component
Performance
Spray Stream
Characteristics
Substrate
Conditions
Coating
Property
Deposition Conditions
Plasma Spray Grey Box
Common Approach for TBC Manufacturing
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Lee et al., J. Europ. Cer. Soc. 25(10):1705-1715 (2005).
Feedstock
Characteristics
Process
Variables
CoatingStructure
Component
Performance
Spray Stream
Characteristics
Substrate
Conditions
Coating
Property
Deposition Conditions
-Feed rate-Raster / Rotation Rate-Angle of Deposition
-Chemistry-Adsorbates-Temperature-Roughness
-Plume Orientation-Plume Spread-Particle State
-Defect (Cracks & Pores)-Crystal (Phase & Composition)-Layering (Splat Characteristics)-Grain (Size)-Anisotropy
-Equipment related (Gun, Gases, Power)
-Particle Injection
-Composition-Morphology-Size Distribution
-Structural Adhesion, Residual Stress, Toughness, Stiffness, Elastic Modulus
-FunctionalElectrical / Thermal transport,Wear / Erosion / Corrosion Resistance
CTSR Approach for TBC Development
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How can modern TS science enhance TBC requirements?
Particle Image
Velocimetry
Particle Image
Velocimetry
Particle Image
Velocimetry
Particle Image
Velocimetry
SPT
DPV
IPP[mm
]
- 10 - 5 0 5 10 15 20x [mm]
- 20
- 15
- 10
- 5
0
5
10
z
Flow
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I II III
What is the difference in these TBC coatings?
15% Porosity 16% Porosity 20 % Porosity
200 400 600 800 1000 1200
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Th
erm
al
Co
nd
uc
tiv
ity
(W
/mK
)
Temperature (oC)
HOSP
A&S
F&C
III
II
I
Stress-strain
III
Strain (%)-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3
Str
ess (
MP
a)
-40
-20
0
20
IIIII
I
Understanding, optimizing and controlling microstructure is critical for design, performance and reliability.
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Thermal spray microstructure has significant influence on material properties
Implications on Properties: Thermal Conductivity
Clarke and Levi, Ann. Rev. Materials, 2003Clarke and Phillpot, Materials Today, June 2005
Nakamura et al., Acta Met, 2004
APS Thermal Conductivity
Is only 40% of Bulk Value
APS PSZ coating
the
rma
l condu
ctivity (
W/m
K)
0
0.5
1
1.5
2
2.5
0
0.5
1
1.5
2
2.5
As-sprayed
As sprayed
Total
reduction
As-sprayedAs-sprayed
As sprayed
Total
reduction
As sprayed
Total
reduction
FE porous
model
FE porous
model
By splat
interfaces
Reduction by Pores
50 m
Thermal cycled
Thermal cycled
(no interfaces)
By splat
interfaces
Reduction by Pores
50 m
Thermal cycled
Thermal cycled
(no interfaces)
50 m
Thermal cycled
50 m50 m
Thermal cycled
Thermal cycled
(no interfaces)
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Integrated Study of Thermal Spray TBCs
1 hour
4 hours
• Understand and control the plasma spray process to tailor and optimize the microstructure
• Develop methodologies for diagnostics, control, microstructure and property quantification
• Establish correlations among process-microstructure-properties so as to affect– Microstructure, thermal conductivity and compliance
• Achieve repeatability and reliability in microstructure and properties
• Assess changes in properties at time and temperature
Provide input for design
Reduce infant mortality and improve reliability
Quantify microstructure evolution for life prediction
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Particle Image
Velocimetry
Particle Image
Velocimetry
Particle Image
Velocimetry
Particle Image
Velocimetry
SPT
DPV
IPP[mm
]
- 10 - 5 0 5 10 15 20x [mm]
- 20
- 15
- 10
- 5
0
5
10
z
Flow
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Integrated Studies of TS Coatings Including TBCs
Stony Brook-Caterpillar Team
Volvo Sweden Field Trip
• Fundamental process science and property
evaluation at CTSR
• Collaborative studies with Consortium members
including field trips to industrial sites
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• Starting powder morphology
• Particle size distribution
• Particle injection
• Plasma torch, power and gases
• Substrate temperature
• Particle flux
• Robot motion
• Examine process/coating repeatability
• Examine testing repeatability
Start the Gun
Set Parameters
Diagnostics
Collect Splats
Diagnostics
Coating for In-situ Curvature
Stop
Low Feed Rate
High Feed Rate
+ Pore Architecture
Modulus (two orientations)
Indentation
Stress-Strain
Thermal Conductivity
(in-plane and through-thickness)
Many parameters can be considered for tailoring a microstructure
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Each Powder Optimized to Produce the Same Average T & V
FC HOSP AS
80 100 120 140 160 180
2450
2500
2550
2600
2650
2700
2750
2800
2850
2900
Te
mp
era
ture
[o C
]
Velocity [m/s]
Fused&Crushed
Flowcenter values
Aggl.&Sint.
PlasmaDensified
Example 1: Effect of Starting Powder Morphology
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71%
9%
20%
Interlamellar pores
Intralamellar cracks
Globular pores
71%
9%
20%
Interlamellar pores
Intralamellar cracks
Globular pores
82%
6%12%
70%
5%
25%
12.4%
10.2%
F&C
HOSP
10.3%
A&S
Similar Total Porosity and
Higher % ILP
Each Powder Optimized to
Produce the Same Average T & V
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
No
rma
lize
d
Pa
rtic
le C
ou
nt
(%)
Temperature (oC)
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
No
rma
lize
d
Pa
rtic
le C
ou
nt
(%)
Temperature (oC)
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
No
rma
lize
d
Pa
rtic
le C
ou
nt
(%)
Temperature (oC)
Example 1: Effect of Starting Powder Morphology
-
20
30
40
50
60
Modulu
s (
GP
a)
20
30
40
50
60
Modulu
s (
GP
a)
F&C HOSP A&S
0.8
1.0
1.2
1.4
Th
. C
on
du
ctivi
ty (
W/m
K)
0.8
1.0
1.2
1.4
Th
. C
on
du
ctivi
ty (
W/m
K) F&C HOSP A&S
71%
9%
20%
Interlamellar pores
Intralamellar cracks
Globular pores
71%
9%
20%
Interlamellar pores
Intralamellar cracks
Globular pores
82%
6%12%
70%
5%
25%
12.36(2)%
10.21(2)%
F&C
10.21(2)%
F&C
10.21(2)%
F&C
PD
10.32(2)%
A&S
10.32(2)%
A&S
HOSPshowsconsistentlylower E and K
Each Powder Optimized to
Produce the Same Average T & V
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
No
rma
lize
d
Pa
rtic
le C
ou
nt
(%)
Temperature (oC)
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
No
rma
lize
d
Pa
rtic
le C
ou
nt
(%)
Temperature (oC)
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
No
rma
lize
d
Pa
rtic
le C
ou
nt
(%)
Temperature (oC)
Example 1: Effect of Starting Powder Morphology
-
71%
9%
20%
Interlamellar pores
Intralamellar cracks
Globular pores
71%
9%
20%
Interlamellar pores
Intralamellar cracks
Globular pores
82%
6%12%
70%
5%
25%
12.36(2)%
10.21(2)%
F&C
10.21(2)%
F&C
10.21(2)%
F&C
PD
10.32(2)%
A&S
10.32(2)%
A&S
0.8
1.0
1.2
1.4
Th
. C
on
du
ctivi
ty (
W/m
K)
0.8
1.0
1.2
1.4
Th
. C
on
du
ctivi
ty (
W/m
K) F&C PD A&S
0.8
1.0
1.2
1.4
Th
. C
on
du
ctivi
ty (
W/m
K)
0.8
1.0
1.2
1.4
Th
. C
on
du
ctivi
ty (
W/m
K) F&C PD A&S
20
30
40
50
60
Modulu
s (
GP
a)
20
30
40
50
60
Modulu
s (
GP
a)
F&C PD A&S
20
30
40
50
60
Modulu
s (
GP
a)
20
30
40
50
60
Modulu
s (
GP
a)
F&C PD A&S
400 800 1200
0.8
1.2
1.6
2.0
K (
W/m
K)
Temperature
HOSP
A&S
F&C
Each Powder Optimized to
Produce the Same Average T & V
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
Norm
aliz
ed
Part
icle
Count (%
)
Temperature (oC)
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
Norm
aliz
ed
Part
icle
Count (%
)
Temperature (oC)
0
1
2
3
4
5
2200 2400 2600 2800 3000 3200
Norm
aliz
ed
Part
icle
Count (%
)
Temperature (oC)
180180
Strain (%)-0.3 -0.2 -0.1 0.0 0.1 0.2 0.3
Str
ess (
MP
a)
-40
-20
0
20
A&SPD
F &C
- - -
A&S HOSP
F&C
40
Example 1: Effect of Starting Powder Morphology
Temperature-dependent K and mechanical behavior differences are observed.
-
Example 2: Changing T-V process space via torch parameters
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
-
Example 2: Changing T-V process space via torch parameters
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
0
500r241
2000 2200 2400 2600 2800 3000 3200
0
500
Temperature (OC)
r245
0
200
400 r247
0
500r249
0
200r243
0
500
Pa
rtic
le C
ou
nt r251
0
500r241
2000 2200 2400 2600 2800 3000 3200
0
500
Temperature (OC)
r245
0
200
400 r247
0
500r249
0
200r243
0
500
Pa
rtic
le C
ou
nt r251
Changing torch parameters effects particle temperature distribution
-
Example 2: Changing T-V process space via torch parameters
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
67 GPa 1.3 W/mK
51 GPa 1.13 W/mK
44 GPa 0.97 W/mK
Changing torch parameters effects microstructure, elastic modulus and
thermal conductivity.
-
Low K
& Compliant
80 100 120 140 160
2400
2500
2600
2700
2800T
em
pera
ture
[°C
]
Velocity [m/s]
80 100 120 140 160
2400
2500
2600
2700
2800T
em
pera
ture
[°C
]
Velocity [m/s]
Poor efficiency
Stiff
2nd Order Process Map
Example 2: Changing T-V process space via torch parameters
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
67 GPa 1.3 W/mK
51 GPa 1.13 W/mK
44 GPa 0.97 W/mK
Process map allows for distinguishing processing effects
-
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
80%
6%
14%
11.1%
29%
64%7%
Interlamella pores
Intralamella cracks
Globular pores
7.7%
29%
64%7%
Interlamella pores
Intralamella cracks
Globular pores
80%
7%
13%9.5%
77%
11%
12%
8.9%
Example 2: Changing T-V process space via torch parameters
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
67 GPa 1.3 W/mK
51 GPa 1.13 W/mK
44 GPa 0.97 W/mK
Total amount and type of porosity can
be controlled
-
Strain
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
Example 2: Changing T-V process space via torch parameters
80 100 120 140 160
2400
2500
2600
2700
2800
Tem
pera
ture
[°C
]
Velocity [m/s]
67 GPa 1.3 W/mK
51 GPa 1.13 W/mK
44 GPa 0.97 W/mK
Mechanical behavior is influenced by
processing
-0.005 0.000 0.005 0.010 0.015-60
-40
-20
0
20
40
60
80
Str
ess (M
Pa
)
s
e
-
Elastic Modulus Map Modulus Variation
Velocity [m/s]
100 105 110 115 120 125 130
Tem
peratu
re [
o C
]
2680
2700
2720
2740
2760
2780
2800
40
42
44
46
48
50
52
54
Thermal Conductivity(scaled)
Velocity (scaled)
20 40 60 80 100
Te
mp
era
ture
(scale
d)
20
40
60
80
100
40
50
60
70
80
90
100
110
120
Thermal Conductivity Map
Example 2: Changing T-V process space via torch parameters
Detailed process maps can be created for use by process and design engineers
-
Microstructural Effects on Mechanical Behavior
Spl
at
Intra-splat columnar grainsInter-splat interfaces
Globular PoresInter-splat Spacing
Cracks within a splatCracks between the splats
Fractured Surface
Cross-section APS-YSZ
Splat
Polished Surface
Cross-section APS-YSZ
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o Mechanism 1: Opening/closure of pores or spacings, the source of Non-linearity
o Mechanism 2: Sliding of defect surfaces causes frictional energy loss, Hysteresis behavior
Non-linearity of the coating represents the compliance present in it
Upon Mechanical Loading
Microstructural Effects on Mechanical Behavior
intersplat
boundary
intersplat
spacing/poreopen
intrasplat crackclosed
intrasplat crackscolumnar
grain boundaries
Surface
friction
1
1
22
Strain (%)
-0.2 -0.1 0.0 0.1 0.2 0.3
Str
ess (M
Pa
)
-30
-20
-10
0
10
20
residual stress
Remained after deposition
Transition
Stress
Non-linear (Mechanism- 1)
Hysteresis(Mechanism- 2)
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In-situ: Curvature Monitoring
Ex-situ: Thermal Cycle of the Coated Specimen
Time (sec)
0 100 200 300 400
Curv
atu
re (
1/m
)
0.0
0.2
0.4
0.6
0.8
1.0
Tem
pera
ture
(oC
)
0
50
100
150
200
250
Spraying Cooling
Curvature
Evolution
Temperature (oC) l
0 50 100 150 200 250
Curv
atu
re (
1/m
)
-0.3
-0.2
-0.1
0.0
0.1YSZ coating on
an Aluminum Substrate
Measurement tells the evolution history of a deposited coating.
Each local peak corresponds to a pass (deposition of one layer). The slope of the curvature evolution is referred as “Evolving stress”
After spraying, the coating (with substrate) is heated inside a furnace. The temperature change induces mismatch strain, and the curvature of coating changes. The continuous recording of one thermal cycle provides an ANELASTIC curv-temp plot, which is then converted to a stress strain curve to quantify the coating compliance.
ICP
Microstructural Effects on Mechanical Behavior
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Microstructural Effects on Mechanical Behavior
Case study: three coatings deposited at three different spray distances
Time (sec)
0 100 200 300 400 500
Cu
rva
ture
(1
/m)
-0.2
-0.1
0.0
0.1
0.2
Evo
lvin
g S
tre
ss (
MP
a)
0
10
20
30
Curvature evolution
during spraySD: 60 mmSD: 100 mm
SD: 150 mm
Temperature (oC)
0 50 100 150 200 250
Cu
rva
ture
(1
/m)
-0.3
-0.2
-0.1
0.0
0.1Curv–temp relationship obtained from
post deposition thermal cycling
SD: 60 mmSD: 100 mm
SD: 150 mm
In-situ Ex-situ
-
Microstructural Effects on Mechanical Behavior
Case study: three coatings deposited at three different spray distances
Strain (%)-0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20
Str
ess (M
Pa
)
-30
-20
-10
0
10
20
30Estimated stress-strain curves
SD: 60 mmSD: 100 mm
SD: 150 mm
Elastic Modulus, E (GPa)
15 20 25 30 35 40N
on
-lin
ea
r D
eg
ree
, N
D1.8
2.1
2.4
2.7
3.0
Non-linear parameters of the
three coatings
60 mm
100 mm
150 mm
0.99 W/m-K
0.82W/m-K
0.69 W/m-K
-
Microstructural Effects on Mechanical Behavior
How could deposits impact mechanical behavior?
Temperature (oC)
50 100 150 200 250
Cu
rva
ture
(1
/m)
-0.02
0.02
0.06
0.10
0.14 In-situ introduction of
salt (NaCl) between
the passes
Coating
without
any salt
50 100 150 200 250
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Temperature (oC)
Cu
rva
ture
(1
/m) Coating with
salt treatment
As-sprayed
coating
without any
treatment
Coating with salt solution treatment was 30% stiffer than as sprayed one. It also showed more hysteresis in it.
Salt mist was introduced between some selective passes during coating deposition.
The presence of salt at defect surfaces made the coating stiffer, with increased non-linearity and hysteresis.
-
As-sprayed Coatings
La2Zr2O7 Gd2Zr2O7 Co-doped YSZ
The
rmal C
on
du
ctivity (
W/m
.K)
0.6
0.8
1.0
1.2
IGCC Turbine Coating Properties: Material Effects
Material choice influences thermal properties
Thermal Conductivity of As-Sprayed Coatings
-
YSZ Co-doped Gd2Zr2O7
Ero
sio
n R
ate
(m
g/g
)
0.0
0.2
0.4
0.6
0.8
90 deg
20 deg
Erosion of As-Sprayed Coatings
Material choice influences erosion properties with Gd2Zr2O7
having high erosion rates.
IGCC Turbine Coating Properties: Material Effects
-
Elastic Modulus [E] (GPa)
15 20 25 30 35 40
De
gre
e o
f N
on
-Lin
ea
rity
[N
D]
1.0
1.5
2.0
2.5
3.0
La2Zr2O7
Gd2Zr2O7
YSZ
Co-doped
Mechanical Behavior of As-Sprayed Coatings
Material choice influences mechanical properties.
IGCC Turbine Coating Properties: Material Effects
-
Gadolium Zirconate Gd2Zr
2O
7
In-flight Particle Velocity (m/s)
80 100 120 140 160 180 200 220
In-f
light
Pa
rtic
le T
em
pe
art
ure
(oC
)
2400
2500
2600
2700
2800
2900
3000
3100
Condition 2
Condition 1
Condition 3
Condition 0
Condition 2Condition 3
Gd2Zr2O7
Cond. 1 Cond. 2 Cond. 3 Cond. 4
Therm
al conductivity (
W.m
-1.K
-1)
0.6
0.7
0.8
0.9
1.0
Condition 4
IGCC Turbine Coating Properties: Processing Effects
-
Gd2Zr
2O
7
Time at 1200 oC isothermal exposure (hours)
0 20 40 60 80 100 120
Th
erm
al co
nd
uctivity (
W.m
-1.K
-1)
0.7
0.8
0.9
1.0
1.1
1.2
1.3
Condition 1
Condition 3
Condition 2
Microstructure influences thermal properties
Condition 1
Condition 3
Condition 4
Condition 1
Condition 4
Condition 3
IGCC Turbine Coating Properties: Processing Effects
-
Thermally Sprayed Multilayer TBC
Sintering resistant
layer
Erosion resistant
layer
Base layer
YSZ
MCrAlYbond coat
Multilayer coating demonstration
-
Modeling of Thermal Conductivity Evolution in a Gradient
Schematic of the model used to predict temperature gradients in TBCs
from thermal conductivity values determined isothermally.
Comparison of isothermal and thermal gradient models with rig test
thermal conductivity and temperature change across the TBC
data showing good agreement
-
Figure 7: This process maprelates NiCr (a surrogate forNiCrAlY) particle states, achievedduring liquid and gas fuel HVOF(Woka and Diamond Jet) andplasma spray (Triplex) toresultant microstructures androughness. Significant differenceamong the TS bond coats exist interms of microstructure, densityand internal oxidation. Thesedifferences can dramaticallyaffect performance. It is criticalto understand these effects tooptimize NiCrAlY bond coats.Maps allow for systematictailoring of coating properties.
Processing Effects on HVOF Bond Coats
-
Summary
Thermal spray
microstructures are
complex with multiscale
features that heavily
influence material
properties.
Thermal Conductivity
Velocity (scaled)20 40 60 80 100
Te
mp
era
ture
(sc
ale
d)
20
40
60
80
100
Advanced thermal spray
processing science allows for
a greater understanding
between parameters, particle
state, microstructure, and
coating properties.
Through the UTSR program, CTSR will
assess multilayer TBCs for coal-gas-derived
systems by investigating new materials and
process-induced properties and their impact
on degradation mechanisms.
Advanced Thermal Barrier Coatings forOperation in High Hydrogen Content Gas Turbines