superior performance. powerful technology.
Progress in production and performance of
second generation (2G) HTS wire for practical
applications
Yifei Zhang, T.F. Lehner, T. Fukushima, H. Sakamoto, and D.W. Hazelton
IEEE 2013 International Conference on Applied Superconductivity and Electromagnetic Devices
October 25-27, 2013  Beijing, China
SuperPower Inc. is a subsidiary of Furukawa Electric Co. Ltd.
Outline
•
•
•
2G HTS wire development and production – an overview
SuperPower Inc. and its 2G HTS wires
Wire quality and performance
–
–
–
–
•
•
•
Uniformity (homogeneity) and piece length
In-field critical current
Electro-mechanical behaviors
Delamination strength
Technology advancement in using 2G HTS wires
Application projects using 2G HTS wires
Summary
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
2
R&D and production of 2G HTS wire
World-wide developers and manufacturers – a glance at the technologies
•
•
•
•
•
A limited number of commercial products providers
Piece length (without splice): 200 ~ 500 meter
Ic (77K, self field): 250 ~ 500 A/cm
Price: 150 ~ 350 $/kAm at 77K, self field
No commercial 2G-based electrical or electromagnetic devices
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
3
SuperPower Inc. – company history timeline
•
Formed within Intermagnetics (IGC) in 2000
2000 ~ 2006
− Strategic Research Agreements with national
labs (LANL, ORNL, ANL)
− Building up strong R&D team and IP
− Supported by government funding
• Intermagnetics acquired by Royal Dutch Philips in 2006
2006 ~ 2012
− Building up strong manufacturing and
marketing teams
− Transition to pilot-scale manufacturing
− Strategic Research Agreement with
University of Houston (TcSUH)
• SuperPower Inc. acquired by Furukawa Electric in 2012
2012 ~ present
All Rights Reserved. Copyright SuperPower® Inc. 2013
− Continuous improvements in quality and
performance
− Steady growth in capacity to meet the market
− Moving towards long-term sustainability
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
4
Voice of the customer provides our roadmap
•
We have provided 2G HTS wires to over 230 customers in 31 countries
•
Electric and electromagnetic devices applications include high-field magnets,
MRI magnets, accelerator magnets, high-current power cables,
superconducting fault current limiters (SFCL), superconducting magnetic
energy storage (SMES), generators & motors, etc.
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
5
Architecture of SuperPower’s 2G HTS wire
IBAD-MOCVD based REBCO wire on Hastelloy substrate
• Substrate (Hastelloy®
C-276) provides
mechanical strength,
electro-polished
surface for
subsequent layer
growth
• IBAD-MgO provides
template for growing
epitaxial buffer layers
• Buffer layers provide:
– Diffusion barrier
between substrate
and REBCO
– Lattice match with
REBCO
All Rights Reserved. Copyright SuperPower® Inc. 2013
• REBCO layer – optimized composition with
nanosized BZO & RE2O3 flux pinning sites for high
in-field Ic
• Ag layer – provides good current transfer to REBCO
layer and facilitates oxygen diffusion during
oxygenation annealing
• Cu layer – provides stabilization (parallel shunt for
electrical current) at transition
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
6
Specification of SuperPower’s 2G HTS wire
• Types of wires:
– AP (Advanced Pinning) – for enhanced in-field performance for coil
applications in motors, generators, SMES, high-field magnets, etc.
– CF (Cable Formulation) – for cables, transformers
– FCL (Cable Formulation) – with tailored Ag layer and thicker substrate
•
Variations in width, substrate thickness, SCS thickness, and insulation
– Insulated wire: polyimide tape wrapped - 30% overlap or butt-wrap
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
7
Quality and performance of 2G HTS wire
•
•
•
•
•
Uniformity along length and across width (Ic and other attributes)
Ic(B, T, )
– engineering current density
– field dependence
– field orientation dependence
– minimum Ic()
Electromechanical properties (mechanical strength)
– axial tensile (irreversible stress or strain limits)
– transverse (c-axis) tensile (along tape surface normal)
– transverse (c-axis) compressive (along tape surface normal)
– transverse compressive (along width)
– bending (with REBCO under compression or tension)
– fatigue (in various stress states)
Quench stability
Splice
– geometry
– resistance (resistivity)
– mechanical strength (tensile and bending)
Standards for 2G HTS wire characterization and testing are under development
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
8
Uniformity along length
• Longer piece length is desired by most targeted devices
− Enable device fabrication
− Affect cryogenics and dielectric designs
• Uniformity (homogeneity) along
length is required for almost every
aspect of wire performance,
including dimension (width,
thickness), Ic(B, T, ), electromechanical behaviors, thermal
properties, etc.
• Localized Ic dropouts – major
reason for shorter piece length,
depending on amplitude and
dimension
• Section-by-section Ic (77K, s.f.)
measured along length by
transport method for each wire
produced
All Rights Reserved. Copyright SuperPower® Inc. 2013
Ic & n-value along length
(Transport measurement)
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
9
Uniformity along length – cont.
• Uniformity in quality and performance along length is achieved by process
control with various techniques, real-time and off-line
Surface roughness of electro-polished substrate, real-time
XRD in-plane texture of cap layer (LMO), off-line
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
10
Uniformity along length – cont.
Ic (A/4mm, 77K, s.f.)
Wire Thickness (µm)
• Uniformity (homogeneity) along length inspected by various techniques for
each wire produced
Position along length (meter)
Thickness along length of fully processed wire, off-line
Position along length (meter)
Ic(77K, s.f.) along length, Hall probe (TapeStar)
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
11
Doping of REBCO to improve in-field performance
H//a-b
H//c
Measured at University of Houston
Ic versus magnetic field orientation at 40K, 3T
TEM cross-sectional image of REBCO
• Introduction of nanoscale defects into REBCO starts with adjusting chemistry
of MOCVD precursor
− Zr content, RE substitution, RE:Ba:Cu ratio
− Effects on formation of BaZrO3 (//c) and RE2O3 (//a-b) nanorods and nanoparticles
• Nanostructure also depends on MOCVD growth condition
− Effects on density, size, orientation & distribution of defects
• Optimization of chemistry and MOCVD deposition condition to meet
performance requirements from different applications (lower-field & highertemperature or higher-field & lower-temperature)
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
12
Ic(B,T,) - critical performance to high-field applications
Data measured at Tohoku University
Courtesy of D. Abraimov & M. Santos, NHMFL
• Ic(B,T) at a certain angle (e.g. B//c) is usually the limiting factor for high field
applications
• Ic(B,T,) – basic to coil and magnet design and applications
• Lift Factor is defined as Ic(B,T, )/Ic(77K, s. f.)
• Ic(B,T,) at high field & low temperature lacks good correlation with Ic(77K, s.f.)
• Ic(B,T,), in addition to Ic(77K, s.f.), needs to be measured for quality control
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
13
IcBT measurement system under construction
for routine production sampling
Target operating conditions
– Temperature: 30K – 77K
– Field: 0 - 2T (65K)
• Higher field operation at 4K
– Field //c and //ab (rotatable 0-225°)
– Sample length in field – min 25 mm
– Maximum sample current 800-1200A
• Full width samples to 4mm wide
– Maximum coil current 400A
• 2G HTS background coils
– Enables testing of production material
in Schenectady (77K-30K, 0-2T) to
evaluate consistency of lift factor
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
14
Tensile stress (strain) limits of 2G HTS wire
•
•
•
•
Stress-strain relationship under axial tensile
load (at room temperature and at operating
temperatures) – basic behaviors
Tensile stress (strain) limit: critical stress
(strain) above which Ic < 95% of zero-stress
Ic(0)
Tensile stress (strain) limits – intrinsic
behavior of REBCO film, strongly
dependent on substrate and affected by
stabilizer
Tensile stress (strain) limits measurements
- Ic measured after applying stress at RT,
compared with zero-stress Ic(0)
- Ic measured WHILE applying stress at
a cryogenic temperature, e.g., 77K,
compared with zero-stress Ic(0)
- Ic measured AFTER applying stress at
a cryogenic temperature, e.g., 77K
- Increase stress level WHILE applying a
constant current, e.g., at 95% of the
zero-stress Ic(0)
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
50µm Hastelloy/100µm Cu
50µm Hastelloy/40µm Cu
15
Addressing the delamination question
•
•
•
•
•
•
Multilayer structure - prone to
77K
delaminating under transversal tensile
stress
Wet Winding
w/ epoxy
Performance degradation of epoxy
impregnated coil observed, due to
Dry Winding
thermal stress in radial direction
through thermal cycling
Cohesive, adhesive or mixed mode
delamination observed
Testing methods developed to
measure delamination strength (c-axis
VI curves of an experimental coil
tensile strength)
Conductor engineering and process modification to reinforce the wire
Techniques developed to mitigate the thermal stress in a coil
Cu
Ag
REBCO
Buffer
Hastelloy
Ag
Cu
All Rights Reserved. Copyright SuperPower® Inc. 2013
Cohesive delamination (within a layer)
Adhesive delamination (at an interface)
Mixed mode delamination (interlaminar)
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
16
Testing methods for measuring delamination strength
P

Peel Test
(SuperPower)
Anvil Tension
(NHMFL)
All Rights Reserved. Copyright SuperPower® Inc. 2013
Anvil Cleavage
(RIKEN)
Anvil Tension
(Andong U.)
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
Stud-Pin Tension
(Fujikura)
Anvil Tension
(SRL/ISTEC)
17
Addressing delamination question – cont.
•
Various pull tests used to measure the c-axis tensile strength, values vary
between several MPa to up to 80 MPa – results good for relative comparison
• Effects of processing conditions on delamination strength found using pull test
(e.g., N. Sakai et al, ISS2012)
• Peel test measures wire’s sensitivity to peel (cleavage) stress, results in
combination with microscopic analysis used to study delamination mechanism
• Peel strength can be improved from near 1 N/cm up to 8 N/cm by modification
of wire processing
• Calculation helps understand
stress level and distribution
• Coil winding techniques developed
to address delamination issue
− Selection of different bobbin
material (Siemens)
− Selection of different epoxy
(KIT, RTRI)
− Advanced technique for wire
insulation (RIKEN)
Load-displacement curves from peel test on experimental wires
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
18
Technology advancement with 2G HTS wire
Roebel Cable
− Fabricated by winding of mechanically punctured
meandering tapes
− Low AC loss, high critical current (~nkA)
− Major developers include IRL (Callaghan) and KIT
− Wire 2D uniformity highly desired
W. Goldacker et al, IEEE TAS , 17(2007)3398
CORC (Conductor on Round Core) Cable
− Fabricated by winding multiple 2G HTS wires in a
helical way around a small former
− High current (7500A at 10mm in LN2)
− Flexible
− Developed by Advanced Conductor Technologies
− Wire strength under complex stress desired
D C van der Laan et al, SUST , 24(2011)042001
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
19
Technology advancement with 2G HTS wire
Twisted Stacked-Tape Cable (TSTC)
− Fabricated by stacking multiple tapes
together and twisting at a pitch length
− High current, compact, and flexible
− Developed by MIT
− Wire strength under complex stress desired
M. Takayasu et al, SUST , 25(2012)014011
Ultra-thin Insulation
− Ultra-thin (~4µm) polyimide film coated by
electrodeposition, scalable process
− Coil PF up to 90% (high current density)
− Improved coil stability
− By RIKEN
Y. Yanagisawa et al, Physica C, 495(2013)15
All Rights Reserved. Copyright SuperPower® Inc. 2013
8µm
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
4µm
8µm
20
Continuous R&D needed, driven by customers
and applications
•
•
•
•
•
•
•
Further improvement in in-field performance
– Hirr at 77K of 15%Zr tapes increased to 14.8T, from 10.2T of
7.5%Zr tape
– Ic(2.5T, 30K) is expected to increased to 1,250 A/cm
– Chemistry tailored for devices with different operation conditions
– Deposition condition optimized for best pinning
– Thicker REBCO layer
Wire filamentization to reduce AC loss
– High throughput, cost-effect and scalable technique
Stabilizer and interfacial resistivity optimization for stability
Simplification of architecture and processing
Methods to fabricate superconducting splice (joint)
Capability of inspecting uniformity reel to reel, along length for quality
and performance characteristics (e.g., in-field Ic)
Processing modification to improve robustness (mechanical strength)
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
21
Application projects using 2G HTS wire
•
“High Performance, Low Cost Superconducting Wires and Coils for High
Power Wind Generators”
− DOE ARPA-E REACT project (Rare Earth Alternatives for Critical Technologies)
− Starting in January 2012, 3 years, $3.1 million
− Develop a low-cost superconducting wire for advanced wind turbine generators
that are lighter, more powerful, and more efficient
− Partners
•
“Superconducting Magnetic Energy Storage System with Direct Power
Electronics Interface”
− DOE ARPA-E REACT project (Rare Earth Alternatives for Critical Technologies)
− Starting from October 2010, 3 years, $4.2 million
− Develop a SMES device that has instantaneous response and nearly infinite cycle
life (2MJ)
− Partners
•
“Fault Current Limiting Superconducting Transformer”
−
−
−
−
DOE Smart Grid Demonstration Program (SGDP) project
Starting from February 2010, 5 years, $21.5 million
Develop a SFCL transformer, 28MVA, 3-phase, 69kV/12.47kV class
Partners
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
22
Application projects using 2G HTS wire – cont.
• 275kV-3kA HTS cable project, Japan
−
−
−
−
−
2008~2013, funded by NEDO MPACC Program
2G HTS wire provided by SWCC, using Fujikura template
Highest voltage HTS cable in the world
Tested to demonstrate long-term reliability
Partners
• Cable specification
−
−
−
−
AC loss and dielectric loss <0.8 W/m at 3 kA, 275 kV
Electrical insulation: PD free at 310 kV, Impulse 1155 kV
Over-current (fault current): 63.0 kA for 0.6 s
Outer diameter <150 mm
• Model cable system testing
−
−
−
−
Including 30m cable, terminations, joint, cooling system
Ic = 6.8 kA for conductor; Ic = 7 kA for shield, at 77K
No PD at AC 310 kV for 10 min
One month testing at 210kV-3kA in Shenyang Furukawa
Cable Corp. in Dec. 2012, equivalent to 30 year operation
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
Courtesy of S. Mukoyama, FEC
23
Summary
•
•
•
•
2G HTS wire provides advantages of high current density, superior
in-field performance, and high mechanical strength for various
electrical and electromagnetic applications
SuperPower’s 2G HTS wire production grows steadily, meeting
performance and volume requirements for different applications,
with continuous improvements in processing and quality underway
Uniformity along length, in-field performance and mechanical
strength (tensile strength and delamination strength) are key
properties important to practical applications and being further
improved with continuous R&D efforts
Application development projects (e.g., SMES, FCL Transformer,
and Wind Turbine Generator) are being pursued at SuperPower to
demonstrate the technology and speed the adoption of the enabling
material
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
24
Thank you for your attention!
谢谢!
Please visit us at our booth!
欢迎访问我们的展台!
For more information: http://www.superpower-inc.com
For questions: info@superpower-inc.com
All Rights Reserved. Copyright SuperPower® Inc. 2013
ASEMD 2013  Beijing, China  Oct. 25-27. 2013
25