novel approach to plasma facing materials in nuclear fusion reactors
DESCRIPTION
Instituto Nacional de Engenharia, Tecnologia e Inovação, I.P. V. Livramento1, J.B. Correia1, D. Nunes3, P.A. Carvalho3, H. Fernandes2, C. Silva2, K. Hanada4, N. Shohoji1, E.Osawa5 1INETI, Departamento de Materiais e Tecnologias de Produção, Estrada do Paço do Lumiar, 1649-038 Lisboa, Portugal - PowerPoint PPT PresentationTRANSCRIPT
Novel approach to plasma facing Novel approach to plasma facing materials in nuclear fusion reactorsmaterials in nuclear fusion reactors
V. Livramento1, J.B. Correia1, D. Nunes3, P.A. Carvalho3, H. Fernandes2,
C. Silva2, K. Hanada4, N. Shohoji1, E.Osawa5
1INETI, Departamento de Materiais e Tecnologias de Produção, Estrada do Paço do Lumiar, 1649-038 Lisboa, Portugal
2Associação Euratom/IST, Centro de Fusão Nuclear, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
3Associação Euratom/IST, Departamento de Engenharia de Materiais, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
4 National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan
5NanoCarbon Research Institute, Ltd. Shinshu University, 386-8567 Ueda-shi Tokida 3-15-1, Nagano, Japan
Instituto Nacional de Engenharia, Tecnologia e Inovação, I.P.
ObjectiveObjectiveProduce a W-nDiamond composite, using High Energy milling of powders and consolidation in order to develop a suitable material for the first wall of nuclear fusion reactors.
Why Nanostructure? Nanoparticles act as effective
sink for radiation defects.
Why W?• Highest melting point;• Highest resistance to irradiation (doesn’t contaminate the plasma);• High corrosion resistance;• Doesn’t produce armful radioactive elements
Why nD?• High thermal condutivity;• Very hard material
Challenge: Avoid the carbide formation!
W-nD nanocomposite is
a good option!
Mechanical Alloying
Experimental Experimental ProceduresProcedures
Processing of elemental powders in high energy ball mills;Dynamic balance between cold welding and fracture gradual mixture; Nanostructure in the end;Especially suited for the production of composite materials.
Inside the Container
Container & Balls
Planetary Ball Mill
Experimental Experimental ProceduresProcedures
Used Powders:• Pure elemental W (99.95% purity; median particle size 1 m)• nD particles; (agglomerates that have diameters of 2-3 m)
WC balls with 10 mm of diameter
250 ml WC containers
The container was first evacuated and then filled with Argon
Retsch PM 400 Planetary Ball Mill
Rotation speed = 200 rpm
Mechanical Alloying:
Experimental Experimental ProceduresProcedures
Characterization of the Resulting
Powders
Scanning Electron
Microscopy
XRD
Microhardness Measurments
Optical Microscopy
Experimental Experimental ProceduresProcedures
Consolidation
Milled Powders
Powders were consolidated by:
• SPS at 800ºC
• Hot-Rolling at 800ºC
• SPS & Hot-Rolling
Consolidated
Material
Experimental Experimental ProceduresProcedures
Spark Plasma Sintering- SPS
Hot-Rolling
SPS at AIST Japan
Experimental Experimental ProceduresProcedures
ResultsResultsProcessing Parameters and Microhardness of all produced batches
BatchMilling Time
[h]Observations Microhardness [HV]
W-nD-2H 2Heterogeneous
powders (several kind of particles)
1558.0±282.8
W-nD-4H 4Heterogeneous
powders (2 kind of particles)
Homogeneous particles (bright) 2427.5±290.2
Heterogeneous and darker particles 1461.0±205.9
W-nD-4HSPS 800ºC
4Homogeneous
powders (1 kind of particles)
2796±271.2.6
W-nD-4HHot-rolling 800ºC
4Heterogeneous
powders (2 kind of particles)
Homogeneous particles (bright) 2780,6±553,2
Heterogeneous and darker particles 1444,0±417,7
W-nD-4HSPS and Hot-rolling
800ºC4
Heterogeneous powders (2 kind of
particles)
Homogeneous particles (bright)2706,5±282,9
Heterogeneous and darker particles1433,1±335,5
ResultsResultsXRD patterns for W+nD powders milled for 2 and 4 hours and consolidated samples:
1
1,5
2
2,5
3
3,5
4
4,5
5
5,5
20 40 60 80 100 120 140 1602 q
W WC W2C WO2 Diam.
W-nD - 2H - 200rpm
W-nD - 4H - 200rpm
W-nD - 4H - 200rpm Lam. 800ºC
W-nD - 4H - 200rpm roll. 800ºC new
W-nD - 4H - 200rpm SPS 800ºC
W-nD - 4H - 200rpm Roll + SPS 800ºC
ResultsResults
SEM/BSE pictures of W+nD powders milled for 2 h and 4h respectively (200rmp):
ResultsResults
SEM/BSE image of W+nD subjected to MA (4 h at 200 rpm) and rolling at 800ºC and respectively EDS chemical analysis:
ResultsResultsW-nD subjected to MA (4 h at 200 rpm) and rolling at 800ºC and exposed to the edge plasma:
ConclusionsConclusions
It is possible to performe MA of W and nD powders at room temperature without agglomeration Short milling time of only 2 and 4 hours provides a favourable condition for the least contamination of ball material in the mechanical alloying.High-energy milling at 200 rpm followed by SPS at 800ºC represents the best combination of processing parameters for obtaining dense W-nD nanocomposite. Bulk specimens were obtained without significant carbide formation.Exposure to plasma of rolled W-nD produced surface modification of structure. However, below 1 mm the W-nD nanocomposite was essentially preserved.
Perspectives of Future Perspectives of Future workwork
Optimize the consolidation parameteres for W-nDiamond
Thermal conductivity tests on the way
More exposure experiments at ISTTOK and at FTU of the Consolidated materials
Novel approach to plasma facing materials in Novel approach to plasma facing materials in nuclear fusion reactorsnuclear fusion reactors
V. Livramento1, J.B. Correia1, D. Nunes3, P.A. Carvalho3, H. Fernandes2,
C. Silva2, K. Hanada4, N. Shohoji1, E.Osawa5
1INETI, Departamento de Materiais e Tecnologias de Produção, Estrada do Paço do Lumiar, 1649-038 Lisboa, Portugal
2Associação Euratom/IST, Centro de Fusão Nuclear, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
3Associação Euratom/IST, Departamento de Engenharia de Materiais, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
4 National Institute of Advanced Industrial Science and Technology (AIST), 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan
5NanoCarbon Research Institute, Ltd. Shinshu University, 386-8567 Ueda-shi Tokida 3-15-1, Nagano, Japan
Instituto Nacional de Engenharia, Tecnologia e Inovação, I.P.
W-nD
W
W-Cu
Cu
Plasma
LAYERS
PropertiesProperties
W
Density W = 19.3 g/cm^3
Hardness Hv W = 3.04 GPa
Thermal Conductivity W = 163.3 W/(m-k)
nDDensity nD = 3.51 g/cm^3Micro-Hardness HV nD = 88 -147 GPaThermal Conductivity nD = 2000 W/(m-k)
SPS- The pulsed DC passes through the graphite die and the compacted powders;- The heat is generated internally, that provides a very high rates of heating and cooling;- This process has the potential of densifying the powders with nanosize or nanostructure avoiding the coarsening which normally accompanies the normal densification routes.
Hot-Rolling- Metallurgical process, where the material is passed, deformed between rolls, applying a controlled load;- permits large deformation of the material with a low number of rolling cycles;- Do not affect microstructural properties;- It’s possible to obtaine material with a certain specification or size.