ORNL is managed by UT-Battelle

for the US Department of Energy

Additive Manufacturing forAdvanced Cooling Technologies

D.L. YouchisonFusion & Materials for Nuclear Systems

R.A. LowdenMaterials Science & Technology

with input from:R.E. NygrenSandia National LaboratoriesD.E. WolfeApplied Research Laboratory, CIMP-3D

FESAC TEC WorkshopJune 20-22, 2017

2 FESAC - Youchison

Cooling channels and joining create complexity

Additive Manufacturing (AM) technology changes the gameApplied heat flux

Glidcop AL-15face plate

Helium exit groove

Glidcop AL-15 fins

Microchannels

Transverse supportbeams

Helium exit channel

Alumina insulation

Inlet plenum

Exit plenum

122 mm

normal flow heat exchanger

Present: intensive use of machining (edm), joining and high part numbers

=low reliability, high

cost

Helium divertor

Blanket module

DOE PM circa 1994: “No swiss

watches!”

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Additive Manufacturing Materials Development Laboratory at ORNL for Accelerator Production of Mo-99

ORNL: Building 4508, Room 224

Selective Laser Melting (SLM) ~ Laser Engineered Net Shape (LENS)

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Selective Laser Melting Process Variables

• Primary Selective Laser Melting (SLM)

Process Variables

- Point Distance (μm)

- Exposure Time (μs)

- Power (W)

- Hatch Distance (μm)

- Layer Thickness (μm)

- Powder Particle Size (μm)

Laser Spot = 130 μmMelt Pool is Dependent Upon

Exposure Time and Power

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Scan or Build Strategy Influences Critical Features Such as Porosity, Microstructure, and Surface Roughness

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Unique Processing Capability Was Established to Examine SLM AM of Molybdenum

Renishaw AM250 400 watt

selective laser melting system

Spot size = 130 mm

Reduced build volume insert for

small-scale experiments

75 x 75 x 60 mm

If needed, system can be returned to standard build volume (250 x 250 x 285 mm)

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A Dedicated Automated Serial Sectioning and Imaging System is Included in the Lab

UES RoboMet.3D

5 x 2 x 1 mm “slices”

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We Too Enjoy a Bit of “Sham Wow”

~ 25 mm

AM MolyTRL3 – TRL4

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SLM Summary

• Targets and components can be produced employing traditional “press and sinter” powder metallurgy and additive manufacturing approaches

• Complete metal powder processing capabilities including reduction, blending, milling, sieving (including inert atmosphere), spray drying and plasma spheroidization are available

• A full-service AM lab has been established to support refractory metal isotope target and assembly fabrication

– SLM AM system with reduced build volume

– Spray drying

– Plasma spheroidization

– Powder characterization

– Automated metallography with 3D image reconstruction

– Glove box

• Reactive or environmentally-sensitive powders can be accommodated. Mo > W > carbides like HfC and SiC

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Advanced manufacturing is needed for fusion Plasma Facing Components (PFCs)

• ARL’s CIMP-3D provides world-class capabilities to benefit a broad range of government and industry sponsors

• The new AM Demonstration Facility has three AM systems, a state-of-the-art design studio and a prototyping lab

FES-PSI workshop white papers highlighted AM. Very flexible AM process builds parts layer by layer using lasers or other techniques that fuse powders or fibers. AM can produce complex spatial features such a micro-cooling channels and materials architecture such as nano-particles, porosity and composition gradients.

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Advanced manufacturing is needed for fusion PFCs

• Using an industrial scale press for field-assisted scintering (FAST), ARL can make complex shapes, such as DIII-D or NSTX tiles or probe heads

• PFCs with composition gradients, controlled porosity, micro-channels for cooling and joints with dissimilar materials

FES-PSI workshop white papers highlighted the need for PFCs with integrated structures and complex spatial features such a micro-cooling channels and materials architecture such as nano-particles, porosity and composition gradients. Field assisted sintering technology (FAST), sometimes called spark sintering, fuses powders under pressure while current passing through the powder creates arcing at contact points.

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Spark Plasma Sintering

TRL4

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Can AM enable development of better helium jets?

10 MPa He

m-dot=10 g/s

Tin=600 C

q”=10 MW/m2

q”

• Large jets• Too many joints

HEMJ from FZK

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1 mm central jet

500 mm jet

Velocity distribution with 10 g/s input

291 m/s

Jets thin the thermal boundary layer that

insulates the wall from the convective fluid.

HEMJ He-cooled Thimble

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Temperatures & stresses inside the capare high. Joint failures are inherent issue.

16 FESAC - Youchison

18 microjet array w/ nozzles

200 mm jets

W faceplate

Outlet plenum

W jetbody

Inlet plenum

q”

} 200 mm standoff

electronics application

Al

17 FESAC - Youchison

Temperature distribution under faceplate

Extensions provide an exhaust plenum

isolated from the jets.

collimated vectors at impingement.

18 FESAC - Youchison366 m/s

200 m/s

vsHe=1738 m/s @ 600 C

Very Uniform Velocity Distribution Exists at Boundary Layer

19 FESAC - Youchison

Microjet arrays could be fabricated in tungsten using AM with integral manifolds. Is it possible?

TRL1

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SPECT collimators from AM tungsten

450 microns

Medical Physics 40, 012501 (2013); doi: 10.1118/1.4769122

Karel Deprez,a) Stefaan Vandenberghe, and

Karen Van Audenhaege, Jonas Van

Vaerenbergh, Roel Van Holen - Belgium

Rapid additive manufacturing of

MR compatible multipinhole

collimators with selective laser

melting of tungsten powder

Successful demonstration

of dimensions not very far

from the microjet feature

sizes we require!

Yes, Likely.

TRL3

21 FESAC - Youchison

8 mm x 8 mm x 8 mm 45 ppi RVC skeleton

Tomography

•VGStudio MAX by

Volume Graphics

File translation

•3dShop by C4W

•Rhino 3d

•Cubit

•Star CCM+

extract a volume

Metallic foams led to advanced recuperators/regenerators

Chemical vapor deposition and infiltration of foam media is advanced manufacturing.

22 FESAC - Youchison

Analysis Reveals Turbulent Mixing and Fin Effect Created by Foam – CVI close-outs demonstrated

Convection models for 2 mm x 2 mm 65 ppi, 10% dense moly foam attached to 1 mm thick moly walls. Temperature distribution is shown on left with velocity vectors and streamlines through the foam on the right.

627 C

27 C He

TRL3

CVI close-outExposed hollow

ligament channels

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Foams can provide compliance, minimize stress

Exploiting Ultramet foams for fusion power conversion!

Li-He HX

TRL5

He-He regenerator

2009

2011

24 FESAC - Youchison

What about low-Z heat sink?newest innovation from ORNL:

• Created a light-weight, low-Z heat sink with the isotropic thermal conductivity of copper, no melting point

– First time ever: heat sink can be a plasma facing material directly or support a refractory metal coating! (disruptive game changer)

• Better heat transfer – lower surface temperatures

• Less mass and longer erosion lifetimes

• Reduced thermal stress in joint due to reduced temperature gradient

• Demonstrated

fabrication

kth=265 W/mK

Cp=1020 J/kgK

density=1.1 g/cm3

Allcomp densified foam>350 W/mK, ~1.5 g/cc

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Morphology consists of high

conductivity graphitic basal

layers oriented along the foam

ligaments, but the ligament

directions are random

Foam microstructure

Uses an Engineered Graphitic StructureDeveloped by James Klett at ORNL

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FOAM

Conductivity in CFC vs Isotropic FoamThe “heatsink” is an important part of the cooling system. It can spread or concentrate the heat flow.

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Isotropic Foam Temperature Distribution

q”=10 MW/m2 k=245 W/mK

h=20,000 W/m2K

10-mm-ID CuCrZr tubeK=334 W/mK

30 mm

TRL3

Near future:PSI-II exposureW7-X exposure

GLADIS mockup

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High-Z coatings

CVD/PVD coatings are a form of advanced manufacturing

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AM used for sensor development

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Risks and Conclusions

• AM allows for near net shape fabrication of refractory metals for PFCs and blankets – Carbides may be possible, but not demonstrated yet?

• Small (~0.1 mm) optimized features are possible

• Scale-up to large area devices is possible

• AM provides dramatic reductions in fabrication costs

• Elimination of joints via graded interfaces

• Reduction in part counts and intricate assemblies

• Useful for heatsinks, armor, blankets and power conversion

• Must increase densities and kth. Powder handling and purity remain issues.

• Helium requires a high pressure safety boundary & robust seals

• Need dedicated test facilities for prototypical testing (NOTHING is >TRL5 without it!)