Electrodeposited Mn-Co Alloy Coating for SOFC … Library/events/2012/13th...Electrodeposited Mn-Co Alloy Coating for SOFC Interconnects H.A. McCrabb 1, B. Kagajwala 2T.D. Hall1, H

Electrodeposited Mn-Co Alloy

Coating for SOFC Interconnects

H.A. McCrabb1, B. Kagajwala1 T.D. Hall1, H. Zhang2,

X. Liu2, S. Snyder1 E.J. Taylor1

1Faraday Technology, Inc. 315 Huls Dr., Clayton, OH 45315 2West Virginia University, Dept. of Mechanical Aerospace Eng. ESB,

Morgantown, WV 26506

13th Annual SECA Workshop

July 25, 2012

PSI Employees

by Education

PSI Locations

Faraday Technology, Inc.

• Faraday Technology specializes

in electrochemical engineering

• www.faradaytechnology.com

• Faraday is a wholly-owned

subsidiary of Physical Sciences,

Inc. (Boston, MA)

• www.psicorp.com

• Collectively, the company

staffs ~185 employees - ~100

with PhDs

• Annual revenue of ~ $50M

slide 2 13th Annual SECA Workshop Pittsburgh, PA, July 24-25, 2012

Platform Technology: Pulse/Pulse

Reverse Processing

Core Competency: Design and Engineer of Novel Electrochemical

Hardware

Total Manufacturing

Solution

• Electronics

• Edge and Surface Finishing

• Engineered Coatings

• Battery and Fuel Cell Power

• Environmental Systems

• Corrosion and Monitoring

Services

• Enables uniform processing

• Applicable for additive or

subtractive electrochemical

processes

• Uniform processing is

achieved over entire substrate,

improving end product

reliability

Either may be applied independently to

improve current industrial practices or may be

combined for a total manufacturing solution

Faraday Technology, Inc.


Achievements

slide 5

• Continued optimization of FARADAYICSM Electrodeposition

Process parameters in order to optimize coating thickness, coating

composition and coating adhesion

• Improved coating uniformity across T441 planar interconnects at

the 100 cm2 scale

• Demonstrated coating process for 25 cm2 430 stainless steel

interconnect containing gas flow fields

• Continued refinement of economic analysis to assess economic

viability of FARADAYICSM Electrodeposition Process for high

volume batch manufacturing

13th Annual SECA Workshop Pittsburgh, PA, July 24-25, 2012

slide 6

FARADAYICSM Processing

Ap

pli

ed E

( - )

Cathodic

Anodic( + )

Forward

modulation

Offtime

Time

Forward

modulation

t1 t0Ap

pli

ed E

( - )

Cathodic

Anodic( + )

Forward

modulation

Offtime

Time

t2

V1

Forward

modulation

Reverse

modulation

(b)(a)

V1

V2

t1

t0

t1

FARADAYICSM Process

+

Conventional (DC) Electrodeposition

• Fast deposition rates

• Simple deposition equipment

• Non-line-of-sight deposition

• Industrially scalable

• Improved electric field control

– Enhanced control of coating thickness

uniformity

– Enhanced control of alloy composition

• Improved coating of “hidden surfaces”


Coating Process

slide 7

• Surface pretreatment to

remove oxide and enhance

coating adhesion

• Electrodeposition to coat

interconnects with Mn-Co

alloy

– Pulse and pulse reverse

electric fields to control

deposit properties

• Elevated thermal treatment

to convert alloy to spinel

Acetone&

Scrub Grit Blast

Rinse&

Scrub

Pickle Dip Rinse Plate

Acetone&

Scrub Grit Blast

Rinse&

Scrub

Pickle Dip Rinse Plate


Phase I Hull Cell Experiments

slide 9

Enables investigation into the effect of various

parameters on deposit properties during a single

experiment

– Current density

– Temperature

– Electrolyte composition

– Additives


Phase I Hull Cell Experiments

slide 10

• Electrolyte without

NaC6H11O7 was selected for

Phase I work on 5 cm x 5 cm

T441 planar substrates

because at reasonable current

densities and metal ion

concentrations results

suggested

– Potential for higher Mn

content in coating

– Less microcracking

– Higher current efficiency

• Faster coating deposition

rates


Phase I Cr Diffusion and Coating Porosity

• Cross-sections of samples that

underwent a soak treatment at

800 C for 500 hrs.

– Coating thickness was as

deposited

– Indicates that the 3 micron

layer has low Cr diffusion and

the 10 micron coating has

negligible Cr diffusion into

coating

– 3 micron coating appears

more porous than 7 and 10

micron film

Substrate Coating surface


Phase I Coating Crystal Structure

10 20 30 40 50 60 70

334

2 theta (degrees)

Inte

ns

ity

(a

.u.)

MnCo2O

4

Mn1.5

Co1.5

O4

Mn1.5

CrO4

332

333

40%Co 3µm

40%Co 7µm

40%Co 10µm

Crystal Structure after 500 hrs. at 800 C

Inte

nsi

ty (

a.u

.)

2 theta (degrees)


Phase I Effect of Thickness and Composition

on Performance

slide 13

The ASR is 60 mΩ cm2 in most cases regardless of compositions

and thickness after 500 hrs. at 800 C

500 600 700 800

0

500

1000

1500

Temperature ( )

AS

R (

m c

m2)

336

337

ASR Behavior after 500 hrs.

85%Co 7µm

85%Co 10µm

mΩ cm2 100 hr 200 hr 500 hr

3 μm 40% Co 35 57 49

7 μm 40% Co 62 7 32

10 μm 40% Co 22 - 36

3 μm 85% Co 31 75 20

7 μm 85% Co 59 40 54

10 μm 85% Co 37 23 22

3 μm 57% Co - 34 26

7 μm 57% Co - - 12

10 μm 57% Co - - 12

ASR at 800 C


mΩ cm

2 100 hr 200 hr 500 hr

3 μm 40% Co 35 57 49

7 μm 40% Co 62 7 32

10 μm 40% Co 22 - 36

3 μm 85% Co 31 75 20

7 μm 85% Co 59 40 54

10 μm 85% Co 37 23 22

3 μm 57% Co - 34 26

7 μm 57% Co - - 12

10 μm 57% Co - - 12

Phase III Program Management Plan

slide 14

Milestones

Fiscal

Year Title

Planned

Completion

Percent

Complete

2011 1. Design/modification of 10” x 10” electrodeposition cell May 2011 100%

2012 2. Long-term high temperature, thermal evaluation August 2012 70%

2012 3. Process development for 4”x4” planar interconnects May 2012 100%

2012 4. Process development for 4”x4” pattern interconnects June 2012 10%

2012 5. Long-term on-cell performance evaluation August 2012 10%

2012 6. Qualification/demonstration of IC in single cell test rig September 2012 0%


Pilot Scale Electrodeposition Equipment

slide 15

Based upon Faraday’s electrochemical cell design that facilitates uniform flow across the surface

of a flat substrate (US patent #7,553,401)


Pilot Scale Experiments

slide 16

• After several tests, issues were noticed with coatings

– Non-uniform current density on front and back of sample during plating

• Poor chemical composition control

• Coating thickness non-uniformity

– Poor coating adhesion

• Anodes removed from system

– Mn fouling

• High surface resistivity

– In the megaohm range after only a few tests

• Can be removed with 30% (v/v) sulfuric acid

Sample Front Sample BackSample Front Sample BackNew

After Testing

Mn fouling


NaC6H11O7 Electrolyte Revisited

slide 17

• Addition of NaC6H11O7 to electrolyte

– Observed benefits

• Boric acid dissolves completely

• Complexing metal ions prevents hydroxide

formation

• Improved buffer capacity

• Anode fouling eliminated

• Improved coating adhesion in as-deposited

state

• Coating deposition rate appears linear

• Maintain coating thickness upon spinel

conversion

~ 20 μm coating

~ 21 μm coating

~3 μm Cr2O3


1110

1110

Varying Coating Thickness


~ 33 μm coating

~ 3 μm Cr2O3

1108

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35 40 45

Rela

tive a

t%

Distance (microns)

C K O K AlK CrK MnK FeK CoK

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

at%

Distance (microns)


~ 10 μm coating

~ 2 μm Cr2O3

1144

~ 21μm coating

~ 3 μm Cr2O3

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

at%

Distance (microns)


1110

Varying Cobalt Concentration


4:1 Co:Mn 6:1 Co:Mn 20:1 Co:Mn

~ 8 μm coating

~ 4 μm Cr2O3

~ 13 μm coating

~ 4 μm Cr2O3

~ 10 μm coating

~ 2 μm Cr2O3 1144 1147 1159

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

at%

Distance (microns)


0

10

20

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

at%

Distance (microns)


0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

at%

Distance (microns)


• Negligible Cr diffusion

• Fairly significant Fe diffusion

• Minor Cr diffusion

• Some Fe diffusion

• Minor Cr diffusion

• Minor Fe diffusion


2 hr. thermal treatment in

air atm prior to thermal soak

2 hr. thermal treatment in H2

atm prior to thermal soak

750 Hour Thermal Soak at 800 C

1136 1137

1137 1136

After 750 hr.

thermal soak

After 750 hr.

thermal soak

750 Hour Thermal Soak at 800 C


2 hr. thermal treatment in

air atm prior to thermal soak

2 hr. thermal treatment in H2

atm prior to thermal soak

1136 1137

750 Hour Thermal Soak Testing


Sample No. Thickness (μm) Atomic%

ASR (mΩ·cm2)

Co Mn

H2 atm exposure for

2 hours followed by

thermal soak for

750 h

1132 7.5 89 11 13.3

1134 10 91 9 16.7

1136 13 92 8 9.6

Air atm exposure

for 2 hours followed

by thermal soak for

750 h

1133 12 85 15 13.0 1135 11 85 15 19.5

1137 14 85 15 13.8

The ASR is 20 mΩ cm2 after 750 hrs. at 800 C

750 Hour Thermal Soak


0

10

20

30

40

50

60

70

80

90

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36

at%

Distance (microns)


800 C 850 C

1123D 1137

Process Scale-up from 25 cm2 to 100 cm2

Coating thickness and

compositional uniformity

at the 100 cm2 scale

– 6:1 Co:Mn

– ~ 12 m coating

– ~4 m Cr2O3 scale

slide 24

CD

B A

E

B A

D C

F E

T441 substrate

MnCo coating

T441 substrate

MnCo coating

F

As-deposited Post-thermal treatment



0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Co

un

ts

Distance (microns)


0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Co

un

ts

Distance (microns)


0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Co

un

ts

Distance (microns)


CD

B A

E

B A

D C

F E

T441 substrate

MnCo coating

T441 substrate

MnCo coating

F

CD

B A

E

B A

D C

F E

T441 substrate

MnCo coating

T441 substrate

MnCo coating

F

Process Scale-up from 25 cm2 to 100 cm2

25 cm2 430 Stainless Steel Interconnect With

Gas Flow Fields


~11 m

~8 m

~15 m

T441 substrate

MnCo coating

~21 m~18 m

• 3 channel serpentine pattern

• Channel width ~ 0.9 mm

• Rib width ~ 0.8 mm

• Channel depth ~ 0.45 mm


25 cm2 430 SS Interconnect With Gas Flow Fields

0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

at%

Distance (microns)


0

10

20

30

40

50

60

70

80

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

at%

Distance (microns)


Top left of channel

Bottom left of channel

25 cm2 430 SS Interconnect With Gas Flow Fields


0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44

at%

Distance (microns)


0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

at%

Distance (microns)


Bottom of channel

Bottom right of channel

Future Work

• Complete thermal soak to 2000 hours for existing samples

• Development, optimization and validation of the

FARADAYICSM Electrodeposition Process for 100 cm2

interconnects with gas flow field features

• Long-term on-cell performance evaluation of button cells

• Qualification/Demonstration of Interconnect Coating in

Single Cell Test Rig under ideal SOFC operating

conditions by potential commercial partners

• Continued development of a more comprehensive

economic assessment of the electrodeposition coating

process as it relates to interconnect manufacturing.

slide 29 13th Annual SECA Workshop Pittsburgh, PA, July 24-25,

2012

Acknowledgments

slide 30

• Briggs White and the entire NETL SECA team

• This material is based upon work supported by the Department of Energy under Award Nos. DE-SC0001023 and DE-FE0006165. Any opinions, findings, conclusions and recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the DOE.

• Contact Information: Heather McCrabb

Ph: 937-836-7749

Email: [email protected]


Documents

Electrodeposited Mn-Co Alloy Coating for SOFC … Library/events/2012/13th...Electrodeposited Mn-Co Alloy Coating for SOFC Interconnects H.A. McCrabb 1, B. Kagajwala 2T.D. Hall1, H