Advanced Thermal Barrier Coatings for Operation in High Hydrogen Content Gas Turbines Christopher Weyant, Sanjay Sampath Center for Thermal Spray Research, Stony Brook University University Turbine Systems Research Workshop October 20, 2010 Research supported by: DOE NETL UTSR DOE Office of Fossil Research STTR with Plasma Technology Inc. AFRL, NSF Consortium 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 Temperature (scaled) 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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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
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
Degradation in IGCC Gas Turbine TBCs
Proposed IGCC Coating Architecture
(Rene 80 or CMSX4)
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
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
<2500.
<5800.
<9100.
<12300.
<15600.
<18900.
<22200.
<25400.
>25400.
Flow
z
z
0
w
injection
spray distance
3D Particle In Flight Diagnostics
exposure
window
in flight properties
crossection distributions
injection monitoring
plume position
plume T
particle melting state
Experiment
heated
substrate
sliding
direction
splat
crossection distribution
Spray Stream Guillotine
In Situ Curvature Sensor
blocker
blocker
coating modulus
and stress state
0 100 200 300 400 500 600-1.0x10
-4
-5.0x10-5
0.0
5.0x10-5
1.0x10-4
1.5x10-4
2.0x10-4
0
50
100
150
200
250
300
350
Prehea
ting
Tem
pera
ture
(°C
)
Cu
rvatu
re (
mm
)-1
Time (s)
Coat
ing
Coolin
g
Modulus Variation
Velocity [m/s]
100 105 110 115 120 125 130
Te
mp
era
ture
[o
C]
2680
2700
2720
2740
2760
2780
2800
40
42
44
46
48
50
52
54
2nd Order Process MapElastic Modulus Contours
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
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
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
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
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
34%
31%
35%
Interlamellar Pores
Cracks
Globular Pores
Temperature-DependentThermal Conductivity
Neutron-based Assessment of Pore Distribution (3D)
Integrated Process Diagnostics
Thermal Aging Effects on Properties
Nonlinear Stress-Strain
15 18 21 24 27 30 33
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
1
2
3
4
5
6
7
8
91
2
3
4
5
6
7
89
Th
erm
al C
on
du
cti
vit
y (
W/m
K)
Total Porosity (%)
As-Sprayed
Isothermal Exposure
Thinner Splats
?=60%
?=50%
15 18 21 24 27 30 33
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
1
2
3
4
5
6
7
8
91
2
3
4
5
6
7
89
Th
erm
al C
on
du
cti
vit
y (
W/m
K)
Total Porosity (%)
As-Sprayed
Isothermal Exposure
Thinner Splats
?=60%
?=50%
Properties dominated by defects, nanoscale
grains, splats interfaces and interphases
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.
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)
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
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
<2500.
<5800.
<9100.
<12300.
<15600.
<18900.
<22200.
<25400.
>25400.
Flow
z
z
0
w
injection
spray distance
3D Particle In Flight Diagnostics
exposure
window
in flight properties
crossection distributions
injection monitoring
plume position
plume T
particle melting state
Experiment
heated
substrate
sliding
direction
splat
crossection distribution
Spray Stream Guillotine
In Situ Curvature Sensor
blocker
blocker
coating modulus
and stress state
0 100 200 300 400 500 600-1.0x10
-4
-5.0x10-5
0.0
5.0x10-5
1.0x10-4
1.5x10-4
2.0x10-4
0
50
100
150
200
250
300
350
Prehea
ting
Tem
pera
ture
(°C
)
Cu
rvatu
re (
mm
)-1
Time (s)
Coat
ing
Coolin
g
Integrated Studies of TS Coatings Including TBCs
• Fundamental process science and property
evaluation at CTSR
Xenon FlashPyro
Cam
SPT
x-y stage
IPP
DPV-2000 Sensor
robot
gun
ICP
Xenon FlashPyro
Cam
SPT
x-y stage
IPP
DPV-2000 Sensor
robot
gun
ICP
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
• 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
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
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
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)
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
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
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