This document summarizes research on the degradation of high-temperature materials used in traditional and modern energy systems. It discusses oxidation and microstructural degradation issues affecting materials in steam generators and fossil fuel plants. It presents experimental data on oxidation kinetics of steels from laboratory tests and power plants. The document also examines challenges for higher-temperature materials in advanced fossil plants. Further, it explores using nanocrystalline alloys and graphene coatings to improve oxidation resistance of materials for solid oxide fuel cells and other applications. The research involves collaboration with multiple universities and industry partners.

1. Degradation of High Temperature Materials
in Traditional and Modern Energy Systems
Ge Le1, Andrew Czerwinski2,4, BV Mahesh1,2,
Manoj K. Mahapatra1, Prabhakar Singh1,
RK Singh Raman2,3
1
Center for Clean Energy Engineering, University of Connecticut, USA
2
3
Department of Mechanical and Aerospace Engineering, Monash
University, Melbourne, Australia
Department of Chemical Engineering, Monash University, Melbourne,
Australia
4
Engineering and Materials Division, HRL Technology Pty Ltd,
Mulgrave, Victoria, Australia
ICAER Conf, IITB, 10-12 December 2013

2. Degradation of High Temperature Materials
in Traditional and Modern Energy Systems
MOTIVATION
•Improving Efficiency and Environmental
Impact of Traditional Systems, and
•Developing New Systems

3. Mitigation of Materials Degradation in
New and Traditional Energy Systems
Degradation, Failure and Fracture
. .
Major Issues in both New and Traditional
Energy Systems

4. Oxidation-assisted Microstructural Degradation of Fe-Cr
Alloys for Nuclear and Coal-fired Plant Steam Generators
2.25Cr-1Mo Steel Weldment (Cross-sections): Steam / 600 oC
Base Metal
Heat Affected Zone (HAZ)
• HAZ: extensive cavity formation at grain boundaries
• Creep resistance of HAZ is generally much inferior
Singh Raman, Metall Mater Trans A (several publications): 1995-2003

5. Improving Efficiency and Environmental
Impact of Traditional Systems
• Higher Temp of Operation:
Supercritical / Ultra-supercritical
Plants (Steam Generators / Boilers)
• Novel / Smarter Approaches to
Monitor Materials Degradation of
High Temp Equipment

6. Challenges for Higher Temperature Materials:
Advanced Fossil Fuel Power Plants
Unique Oxidation Test Facility: Loy Yang B Power Station,
Australia
Testing Using Real
Power Plant Steam
A joint facility of:
- Five Power plants
in Vic state,
- Vic State Govt,
- Monash Univ,
- HRL Technology,
- Oak Ridge
National Lab, USA
PhD project: 12,000 h data

7. Lab Test Facility for Oxidation Kinetics Data:
Fossil Fuel Plant Steam Generators

8. Lab and Power Plant Oxidation Kinetics Data:
Steam Generator 9Cr-1Mo Steel (T9)
Good agreement in plant and laboratory data

9. Lab and Power Plant Oxidation Kinetics Data:
Steam Generator 9Cr-1Mo Steel (T92)
No good agreement in plant and laboratory data

10. Extrapolation of Plant Oxidation Kinetics Data:
Steam Generator 9Cr-1Mo Steels
(T92: V+Nb+W, T91: V+Nb, T9: plain)

11. Mitigation of Materials Degradation in
An Alternative Energy System (e.g., SOFC)
- 70% cost of SOFC: Interconnection / BOP materials
- Chromia evaporation: cell contamination

12. Suppression of Chromium Evaporation
Least Cr Evaporation from Aluchrom Alloy
Ge, Verma, Goettler, Lovett, Singh Raman, Singh, Oxide Scale Morphology and Cr
Evaporation Characteristics of Alloys for Balance of Plant Applications in Solid
Oxide Fuel Cells, Metallurgical & Materials Trans A, 44a (2013) 193 – 206.

13. Suppression of Chromium Evaporation: FIB
(Cr,Mn)3O4
Nicrofer 6025HT
Cr2O3
Ni, Fe, Cr
mixed oxide
AISI 310S
Cr2O3
Al2O3
Al2O3
Aluchrom:
850 oC / 3% humidity
Aluchrom:
950 oC / 12% humidity
Ge, Verma, Goettler, Lovett, Singh Raman, Singh,
Metall & Mater Trans A, 44a (2013) 193 – 206.

14. Mitigation of Materials Degradation:
Grain Size Effect
Oxidised 2.25Cr-1Mo
steel (550oC)
Extensive Grain
Boundary
oxidation /
Notching / Grain
detachment
Grain Boundary Corrosion is Expected to be
Extremely Enhanced in the Case of
Nanocrystalline Alloys
Singh Raman et.al., J. Mater Sci Letters,
9 (1990) 353

15. Remarkable Oxidation Resistance due to
Nanocrystalline (nc) Structure of Fe-Cr Alloys
1.2
2
1
mc, 30 min
mc, 2 hr
mc, 52 hr
0.8
microcrystalline (mc)
nanocrystalline (nc)
0.6
0.4
0.2
c
/
m
,
u
r
p
n
a
t
h
g
i
e
W
nc, 30 min
nc ,52 hr
nc, 2 hr
0
0
500
1000
1500
2000
time, min
2500
3000
3500
Oxidation (300 oC / Air) of nc and mc Fe-10Cr Alloys
Singh Raman, Gupta, Koch, Philosophical Magazine, 90 (2010) 3233

16. Oxidised nc and mc Fe-10Cr Alloys
mc
nc
Oxidised: 350oC / Air / 52h

17. nc and mc Fe-10Cr and Fe-20Cr Alloys
Oxidized (300oC/120min): Cr Depth Profiles
1.0E+07
Cr - Profile
8.0E+06
6.0E+06
4.0E+06
c
e
/
s
t
n
u
o
C
nc Fe20Cr
mc Fe20Cr
nc Fe10Cr
mc Fe10Cr
2.0E+06
0.0E+00
0
100
200
300
400
Time, sec
500
600
Singh Raman, Gupta, Corrosion Science, 51 (2009) 316

18. Our Nanocrystalline Fe-Cr Alloys Find Potential
Application in Clean Energy Systems
Solid Oxide Fuel Cells (highest efficiency fuel cells)
* High Cr alloys for Interconnect, Heat exchanger, Piping
* Materials Issues:
- 70% cost: Interconnection / BOP materials
- Chromia evaporation: cell contamination
Rolls
Royce
Solid
Oxide
Fuel
Cell

19. Effect of temperature on on Grain Growth
Effect of Tamperature and Zr Additiongrain growth
• Rapid grain growth above 600 °C
• Addition of Zr stabilizes the grain size even at 1000 °C !!
M
ONASH
University
- ARC Discovery
and
- North Carolina
State University
Mahesh, Singh Raman, Koch , J. Mater. Sci. 47 (2012), 7735-7743

20. Graphene: ‘Thinnest Known Corrosion Resistant Coating’
Graphene: Flat monolayer of sp2 hybridized carbon atoms
arranged in a 2D honeycomb lattice
Single layer of
graphite

21. Remarkable Mechanical Properties of Graphene
 Young’s modulus: 1 TPa
(steel ~0.2 TPa)
 Stiffness: 1060 GPa
 Graphene film vs Steel
(similar thickness):
Graphene is 100 times
stronger than the strongest
steel
1 m2 graphene can bear
4 kg mass

22. Remarkable Mechanical Properties of Graphene
 Impermeable
to most standard gases, including He
 Impermeable to most fluids including small molecules
 Inert even to most aggressive chemicals (e.g. HF)
 Hydrophobic due to the non-polar covalent double bonds
Can Graphene act as a
corrosion barrier?

23. Corrosion / Oxidation Resistance due to Graphene Coating
Graphene coated upper
half of the penny (Cu
Alloy) does not corrode
Chen S, Brown L, Levendorf M, Cai W, Ju S-Y, Edgeworth J, et al.
Oxidation Resistance of Graphene-Coated Cu and Cu/Ni Alloy,
ACS Nano. 2011 2012/01/26;5(2):1321-7

24. Potential (V) vs SCE
Comparison of Corrosion Data
from Different Groups
graphene coated Cu
uncoated Cu
0.1
0.05
 Anodic current density is an order of
Prasai et al
0
-0.05
magnitude lower (in Na2SO4)
-0.1
 Ecorr has shifted towards more noble
direction
-0.15
-0.2
-0.25
Potential (V) vs SCE
-0.3
0.5
0.4
Kirkland et al
0.3
 Anodic current density is similar
0.2
0.1
(in 3.5% NaCl)
0
-0.1
 Ecorr is more negative
-0.2
Potential (V) vs SCE
-0.3
-0.4
0.4
Best corrosion resistance
 Anodic current density is two
orders of magnitude lower coating
due to graphene
(in 3.5% NaCl)
till date!
Singh Raman et al
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
Ecorr is 40 mV more positive
-0.4
-0.5
-9
-8
-7
-6
-5
-4
2
log i (A/cm )
-3
-2
-1

25. EIS of Graphene-coated and Uncoated Cu
|Z| (Ω cm2)
1000000
Graphene coated Cu
Uncoated Cu
10000
100
1
0.01
1
100
10000
1000000
Frequency (Hz)
Confirmation of two orders of magnitude higher corrosion
resistance due to graphene coating
Singh Raman, Banerjee.....Ajayan, Majumder et al, Protecting copper from
electrochemical degradation by graphene coating, Carbon, 50 (2012) 4040.

26. External Collaborators: Raman Singh
• Centre for Clean Energy Engineering (C2E2), University of
Connecticut,
• US Office of Naval Research (ONR), Naval Research Lab (NRL)
• North Carolina State University (Prof K Koch)
• Consortium of Five Power Generators in Vic state, and HRL
Technology
• Rice University (Prof PM Ajayan)
• ETH, Zurich (Prof P Uggowitzer)
• Technion (Prof Dan Schechtman)
• Alcoa, BHP-Billiton
• Australian Vinyls
• DSTO, CSIRO, IITB-Monash Research Academy