HTS Wires & Tapes for Tough Applications like high field ...

HTS Wires & Tapes for Tough Applications like high field magnet windings

ICMC June 2014

Alexander Otto, PhD.

Solid Material Solutions (SMS)

Solid Material Solutions (SMS)

Founded 2012 Alex Otto Linda Saraco Bill Carter

Basis As experienced innovators in HTS technology we are uniquely positioned to make pivotal contributions to superconductor development and commercialization

• Basic superconductivity-related materials, process and test development • Powder-In-Tube (PIT) production and product technology • 2G processing and product technology • Scale up to high yield, long length, low cost manufacturing

Location central to the Northeast’s HTS and LTS development hub

1

Acknowledgements

The Applied Superconductivity Center at the NHMFL

Sumitomo Electric Industries

Oxford Superconducting Technology

Dmytro Abraimov

Problem and Opportunity

Problem Addressed 2212 & 2223 mechanical properties inadequate for high field magnets

Reinforcement Opportunity 2212 similarity to 2223 and prior work provides possibility for

Innovative, low-cost, rapid adaptation of existing technology Development of technology that can be readily applied to both systems Applying unique expertise for mechanical property improvement

Primary Mechanical Property Goals 2223: Tensile stress to > 500 MPa, strain to > 0.35%, good for very high field magnet 2212: Tensile stress to > 300 MPa, strain to > 0.35%, react and wind threshold Acceptable axial compressive properties, as shown by bending All other properties acceptable, at most 30% reinforcement area

2212 and 2223 conductor Je good for high field use at <10K • 2223 tape: Je decline is most gradual above 10T even though self field Je lower

Most commercial, made at relatively low cost, in long lengths • 2212 wire: Je in field surpasses even YBCO 2G tape Je

Round form is versatile, easier to use and cable than 2223 or YBCO tape

In Field Je Defines Reinforcement Headroom

From: 1) Data compiled by P. Lee at the NHMFL – ASC, 2) Data AMSC 2223 tape generated by H. Weijers and 3) Data on SEI 2223 tape generated by Dmytro Abraimov 4) Test data generated by A. Otto

Reinforcement by Solder Lamination After Completing HTS Processing

Material Approach • Increase composite modulus

• Put HTS in optimal axial stress state

• Make it more difficult for cracks to propagate through HTS

• Make it more difficult for surfaces to indent

Challenges • Geometric uniformity

• No damage to HTS

• Finding / suitable reinforcement materials

• Establishing process conditions

• Minimal reduction of current density due to added material

Schematic of reinforcement attachment and internal strain control

Ftape

Fstrip

Fstrip

Ftotal

Reinforcement strip attached to HTS tape by molten solder wetting, and solidification, with applied forces to adjust internal strains

Hot and

Molten Chilled and

Solid

Strain

Stress

sc

(NR

)

Ic

Down

HTS ec

Unreinforced tape

ec: Axial Strain Tolerance

sc

: A

xia

l S

tre

ss T

ole

ran

ce

Un reinforced oxide / Ag composite wire or tape

Increases tensile stress tolerance

Effect of adding high modulus strip

Strain

Stress

sc

(NR

)

Ic

Down

With high modulus strip

HTS ec

sc

(HM

S)

Unreinforced tape

ec: Axial Strain Tolerance

sc

: A

xia

l S

tre

ss T

ole

ran

ce

Increases tensile yield stress tolerance more, decreases compressive stress tolerance

Effect of high modulus, high yield strain strip plus pretension

Strain

Stress

sc

(NR

)

Ic

Down

With high modulus, high yield strain strip

HTS ec

sc

(HM

S)

With large strip tension

Unreinforced tape

sc

(HM

S+

T)

Axial compression of HTS in composite

ec: Axial Strain Tolerance

sc

: A

xia

l S

tre

ss T

ole

ran

ce

Increases tensile yield stress tolerance more, decreases compressive stress tolerance

Effect of high modulus, high yield strain strip, plus pretension, plus high CTE

Strain

Stress

sc

(NR

)

Ic

Down

With high modulus, high yield stress,

higher CTE strip

HTS ec

sc

(HM

S)

With large strip tension

Unreinforced tape

sc

(HM

S+

T)

With large CTE in strip cool down

sc

(HM

S+

T+

CT

E)

Axial compression of HTS in composite

ec: Axial Strain Tolerance

sc

: A

xia

l S

tre

ss T

ole

ran

ce

Increases axial strain tolerance window size; tensile and compressive stress and strain tolerance

Strain

Stress

sc

(NR

)

Ic

Down

With high modulus, high yield strain,

high CTE strip, plus inhibited

crack propagation

Ec(0)

sc

(HM

S)

With large strip tension

Unreinforced tape

sc

(HM

S+

T)

With large CTE in strip cool down

sc

(HM

S+

T+

CT

E)

Axial compression of HTS in composite

ec: Axial Strain Tolerance

sc

: A

xia

l S

tre

ss T

ole

ran

ce

Effect of high modulus, high yield-strain strip, pretension, high CTE, plus inhibited crack propagation and buckling

Ec(R)

HTS critical strain

Improvement possible up to acceptable compression limit of HTS

Strain

Stress

sc

(NR

)

Ic

Down

With high modulus, high yield strain,

high CTE strip, plus inhibited

crack propagation

Ec(0)

sc

(HM

S)

With large strip tension

Unreinforced tape

sc

(HM

S+

T)

With large CTE in strip cool down

sc

(HM

S+

T+

CT

E)

Axial compression of HTS in composite

ec: Axial Strain Tolerance

sc

: A

xia

l S

tre

ss T

ole

ran

ce

Ec(R)

WA

RN

ING

: H

TS

Ax

ial

co

mp

ressiv

e s

tra

in L

imit

Reinforcement limit

2223/Ag Tape Reinforcement Work In collaboration with and supported by Sumitomo Electric Industries

Prior Status • Lamination reinforcement with stainless steel strip established at SEI and AMSC • 500 MPa requires too much stainless, reduces Je below half its original value

Method Apply model , find candidate materials, process conditions Develop solder-able strip supply chain Produce strip of required quality, length Make reinforced tape, and test samples (by and at SEI)

Very good agreement between data and model

Model and Data: Stainless Reinforcement

Calculated

Measured

Many material system to consider but very few meet all requirements…

The search for better material than stainless

Look for materials with best combination of

Higher modulus than stainless Higher proportional limit than stainless to allow larger strip tension Higher CTE than stainless

Plus Non magnetic Not too electrically resistive – like stainless or better Can be easily made wet-able Reasonable cost Available… or not too great a development effort to obtain Non toxic

Rare combination of properties in the direction of goodness well past stainless

Candidate Evaluation and Selection

Co-Cr-No alloys identified as overall most promising From technical, scientific and product literature Modulus 220 GPa – 240 GPa; 20 – 30% better than stainless Proportional Limit up to 0.9%; 300% better than stainless CTE 13 to 14.5 ppm m/m/K 10 – 20 % lower than stainless

Property New Stainless Steel Young’s modulus (GPa) 221 182 Proportional limit stress (MPA) 2000 400-600 Proportional limit strain (%) 0.9 0.25-0.3 CTE (ppm / K / m) 13 16

New Strip Material Stress-Strain Data

Successful demonstration of feasibility; SEI continues product development

Development

At SMS: Development completed Produce sheet and strip in required thickness and width Attain proper metallurgical state for above properties Render the strips adequately wet-able by solder

At SEI:

Reinforced samples produced by long length reel to reel process

Key properties tested

Reinforced 2223/Ag 200 A tape with 540 MPa stress tolerance at 77 K

n

> 500 MPa tolerance with 30% reinforcement area by long length process

540 MPa result for 2223

Reinforced 2212 round wire

Goal 2212 for react-and-wind cabling, coil winding and use in demanding high field conditions Step 1: Feasibility of > 300 MPa with < 30% reinforcement put on by scalable approach

Concept – similar to 2223 reinforcement Surround 2212/Ag wire with high modulus, high yield strip, attach in tensile stressed state

Basis Apply previously described design model

Challenge Reinforcing round 2212/Ag without giving up too much Je, geometric / property uniformity

Cross section of SEI 2223 500 MPa stress tolerant tape

Schematic of reinforced round 2212 / Ag wire

Stainless Reinforced 2212 / Ag Design Summary

Stainless Steel on 0.8 mm Diameter 2212 / Ag Round Wire Area Percent Reinforcement 24 38 0 Stress Tolerance (MPa) 300 400 130 Tensile Strain Tolerance (%) 0.35 0.4 0.24 Compressive Strain Tolerance (%) -0.2 -.22 0.21 Strain Window Size ( Compr. To Tens.) 0.55 0.62 0.45

PRACTICAL REINFORCED 2212 SEEMS FEASIBLE React and wind, Suitable for high field magnets

Test bed for reinforced 2212 / Ag development

Process Concept Form cylindrical strip from flat strip Fold wire inside opened cylindrical strip Impregnate and wet with solder Compress and solidify with tension in strip(s)

Reinforcement strip with solder wetted surface

viewed edge on

Apply Tensile Force

Shape into split cylinder

Insert wire

C Immerse

into molten solder

Apply rapid

cooling

Apply Tensile Force

Rotate to move

2212 / Ag round wire

Molten solder

Test bed built, very first trial runs ongoing Self funded so far, require additional funds to complete

SUMMARY

1) Solder wet-able very high yield stress, high modulus strip developed for solder lamination of HTS tape and wire.

2) 540 MPa tensile stress tolerance demonstrated for 2223 based

tape with 30% of added reinforcement by solder lamination. 3) 2212/Ag round wire design shows 300 MPa and 400 MPa

achieved with 24% and 38 % of added stainless reinforcement 4) Test bed results – pending – first trial runs underway.

Dankuwel Thank You

55 Middlesex Street,

Chelmsford, MA 01863

(978) 808-9016 cell

(978) 455-7182 office

www.solidmaterialsolutions.com

Alexander Otto, PhD. Solid Material Solutions

SMS is central to the Northeast’s

HTS and LTS development hub