advanced thermal barrier coatings for operation in high ......volvo aero c hromalloy icp thermal...

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

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

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

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

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

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

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

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


(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


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)


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


Globular pores

71%

9%

20%

Interlamellar pores


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



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)


71%

9%

20%

Interlamellar pores


Globular pores

71%

9%

20%

Interlamellar pores


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



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


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]


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


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


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%


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]


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


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


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



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


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


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.


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.


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.


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

advanced thermal barrier coatings for operation in high ......volvo aero c hromalloy icp thermal...

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