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!”
3 FESAC - Youchison
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)
4 FESAC - Youchison
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
5 FESAC - Youchison
Scan or Build Strategy Influences Critical Features Such as Porosity, Microstructure, and Surface Roughness
6 FESAC - Youchison
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)
7 FESAC - Youchison
A Dedicated Automated Serial Sectioning and Imaging System is Included in the Lab
UES RoboMet.3D
5 x 2 x 1 mm “slices”
8 FESAC - Youchison
We Too Enjoy a Bit of “Sham Wow”
~ 25 mm
AM MolyTRL3 – TRL4
9 FESAC - Youchison
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
10 FESAC - Youchison
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.
11 FESAC - Youchison
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.
12 FESAC - Youchison
Spark Plasma Sintering
TRL4
13 FESAC - Youchison
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
14 FESAC - Youchison 14
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
15 FESAC - Youchison
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
20 FESAC - Youchison
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
23 FESAC - Youchison
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
25 FESAC - Youchison
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
26 FESAC - Youchison
FOAM
Conductivity in CFC vs Isotropic FoamThe “heatsink” is an important part of the cooling system. It can spread or concentrate the heat flow.
27 FESAC - Youchison
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
28 FESAC - Youchison
High-Z coatings
CVD/PVD coatings are a form of advanced manufacturing
29 FESAC - Youchison
AM used for sensor development
30 FESAC - Youchison
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!)