current status of lithium ceramic pebble manufacturing in korea yi-hyun park 1, in-keun yu 1,...
TRANSCRIPT
Current Status of Lithium Ceramic
Pebble Manufacturing in Korea
Yi-Hyun Park1, In-Keun Yu1, Mu-Young Ahn1, Seungyon Cho1,
Duck Young Ku1, and Sang-Jin Lee2
1 National Fusion Research Institute, Daejeon, Korea2 Mokpo National University, Jeonnam, Korea
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Contents
2
Ⅰ
Ⅱ
Ⅲ
Ⅳ
Background
R&D Status-1 : Synthesis of Li4SiO4 Powder
R&D Status-2 : Fabrication of Li4SiO4 Pebble
Compression Molding Method
Slurry Droplet Drying Method
Slurry Droplet Wetting Method
Summary and Future Works
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Background
3
Korea Helium Cooled Solid Breeder TBM (KO HCSB TBM)
• Reduced Activation Ferritic/Martensitic steel as structural material
• Li4SiO4(LS) or Li2TiO3(LT) pebble as breeder
• Be pebble as multiplier• Graphite pebble as reflector
SiC coating is necessary to avoid air/water contact, to enhance pebble strength, and to handle easily.
Parameter Values
FW heat fluxAverage 0.3 MW/m2
Peak 0.5 MW/m2
Neutron wall load 0.78 MW/m2
Thermal Power 1.01 MW
Tritium Breeding Ratio
1.1
Structural material RAFM (< 550 oC)
Breeder
Li4SiO4 pebble bed
Li2TiO3 pebble bed (optional)
< 920 oC
MultiplierBe pebble bed< 650 oC
Reflector Graphite pebble bed
Size 1208x710x600 (mm)
Coolant
8 MPa He0.973 kg/sFW ( 300 oC / 390 oC ) Breeding Zone(390 oC/500 oC )
Purge He with 0.1 % H2
FirstWall
BreedingZone
TopPlate
BackManifold
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Required Properties for Li-ceramic
4
Material Property Requirement Remarks
Powder
Particle Size < 0.5 μm success (LS)
Crystalline Phase > 98.5 % success (LS)
ImpuritiesCo : < 1 ppmAl : < 35 ppm
from activation/waste
Pebble
Particle Size < 10 μm need to control
Diameter 1.0 mm need to control
Porosity < 20 % need to control
Sphericity < 1.05 -
Crush Load > 15 N -
Quality Controllability, Mass Production,High-yield, Good Reproducibility,
Reprocessing (Recycling)
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Contents
5
Ⅰ
Ⅱ
Ⅲ
Ⅳ
Background
R&D Status-1 : Synthesis of Li4SiO4 Powder
R&D Status-2 : Fabrication of Li4SiO4 Pebble
Compression Molding Method
Slurry Droplet Drying Method
Slurry Droplet Wetting Method
Summary and Future Works
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Synthesis Process of Li4SiO4 powder
6
Synthesis Process for Li4SiO4 powder by PVA Solution Route
• Lithium Nitrate (LiNO3)
• Silica sol (SiO2)
D.I. water
PVA
5 wt.% PVA solution
D.I. water
Mixing (entrapment)
Drying (Li4SiO4 ceramic precursor)
Calcination & Crystallization
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Thermal Analysis of Li4SiO4 Precursor
7
Thermo Gravimetry (TG) / Differential Thermal Analyzer (DTA)
The calcination process was finished below about 800 oC.
Crystallization Process : >800 oC
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Synthesized Li4SiO4 Powders
8
Effects of Crystallization Temperature
800oC
1000oC
900oC
Primary Particle Size : about 200 nm
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Synthesized Li4SiO4 Powders
9
Low Mw
High MwLow Mw High Mw
Effects of PVA Type
Effects of PVA Content
5 wt.% 10 wt.%
5 wt.%
10 wt.%
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Contents
10
Ⅰ
Ⅱ
Ⅲ
Ⅳ
Background
R&D Status-1 : Synthesis of Li4SiO4 Powder
R&D Status-2 : Fabrication of Li4SiO4 Pebble
Compression Molding Method
Slurry Droplet Drying Method
Slurry Droplet Wetting Method
Summary and Future Works
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Fabrication of Pebble : Compression Molding Method
11
PVA solutionLi4SiO4 powder
Mixing
Pressing using Compression Mold
Sintering
Granulation
Fabrication Process of Compression Molding Method
Li4SiO4 Granules
Compression Mold for Pebble
Dia. : about 0.3mm
PVA cont.: 5~10wt.%
Punch Spherical
Green Body
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Strength Properties
12
0 0.02 0.04 0.06 0.08 0.1 0.120
20
40
60
80
100No.1No.2No.3No.4No.5
Displacement (mm)
Lo
ad
(N
)No. Dia. (mm) Crush Load (N) Max. Contact Pressure (GPa)
1 2.10 67.4 5.60
2 2.17 93.9 6.13
3 2.12 66.8 5.55
4 2.13 72.5 5.69
5 2.12 75.9 5.80
• Equipment : Micro-force Material Tester• Cross-head Speed : 0.5 mm/min• Test Temperature : R.T.
Pebble
Upper anvil
Lower anvil
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Fabrication of Pebble : Slurry Droplet Drying Method
13
Fabrication Process of Droplet Drying Method
by using Hydrophobic Cloth
D.I. waterLi4SiO4 powder
Mixing (1:2 wt.%)
Dropping on Hydrophobic Cloth
Drying (24h)
Rolling
Sintering
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Photographs of Green Bodies
14
slurry droplets
as-dried green body rolled green body
rolling(3h, 100 rpm)
Average diameter of rolled green body was about 1 mm.
It could be easily controlled by changing of rolling conditions.
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Fabrication of Pebble : Slurry Droplet Wetting Method
15
Fabrication Process of Dropping Wetting Method
by using Hydrogen Peroxide Solution
PVA solution
D.I. waterLi4SiO4 Powder
PVA
Mixing
Dropping into 34%-H2O2 solution
Drying (R.T., 12h)
Sintering
Li4SiO4
powder
10wt.%
PVA solution
slurry
syringe needle
H2O2 solution
gel-sphere
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Photographs of Gel-spheres
16
Dropped and Floating Gel-spheres
gel-sphere
gel-sphere
bubble
after
30 seconds
After about 30 seconds settling at the bottom,
Li4SiO4 gel-spheres came up to the surface of the H2O2.
Decomposition Reaction of H2O2 :
2 H2O2 (aq) 2 H2O (l) + O2 (g)
Flat surface was not observed at the gel-sphere.
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Photographs of Green Body and Pebble
17
Spherical Green Bodies and Sintered Li4SiO4 Pebbles
sintering(1000oC, 4h, in air)
spherical green bodies sintered Li4SiO4 pebbles
average diameter : 2.5 mm average diameter : 1.5 mm
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
XRD Patterns of Powder and Sintered Pebble
18
2θ (o)
Inte
nsi
ty (
cou
nts
)
pebble
powder
Li2Si2O5 and SiO2 included in starting powder were reacted and removed by sintering process.
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Crush Load and Microstructure
19
-0.02 0.03 0.080
5
10
15
20
25
30
35
40
Displacement (mm)
Co
mp
ress
ive
Lo
ad
(N
)
50μm
10μm
Diameter : about 1.5 mm
0.5 mm/min
Room Temp.
Crush Load : 15 N ~ 35 N
Particle Size < 10 μm
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Contents
20
Ⅰ
Ⅱ
Ⅲ
Ⅳ
Background
R&D Status-1 : Synthesis of Li4SiO4 Powder
R&D Status-2 : Fabrication of Li4SiO4 Pebble
Compression Molding Method
Slurry Droplet Drying Method
Slurry Droplet Wetting Method
Summary and Future Works
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA
Summary and Future Works
21
Pure and stable Li4SiO4 powder was successfully synthesized by
polymer solution route employing PVA as an organic carrier.
Li4SiO4 pebbles with relatively high sphericity, high strength and
fine grain size could be successfully fabricated by a compression
molding method, a slurry droplet drying method, and a slurry
droplet wetting method.
It is expected that these methods are easily-controllable and high-
yield process for solid breeder pebbles.
These methods should be constantly improved for high perfor-
mance of Li-ceramic pebbles such as high-temperature properties,
irradiation properties, and recycling process.
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA 22
Thank you for Your Attention !!!
CBBI-16, Sep. 8-10, 2011, Red Lion on the River, Portland, OR, USA 23
(a) Excess or not enough polymer results in large particle size distributions. (b) the optimal amount should give a more uniform distribution.
O : cation ion~ : polymer chain
PVA type and mixing amount
Two types of PVA
High degree of polymerized PVA:D.P. value = 1625 (monomers/polymer)
molecular weight = 153,000
Low degree of polymerized PVA: D.P. value = 428(monomers/polymer)
molecular weight = 40,000
PVA content The proportions of the PVA to cation sources in the
solution were adjusted in such a way that there were 0.5~1 times more positively charged valences from the cations than from the potentially nega-tively charged –(OH) functional groups of the
polymers.
PVA amount of polymer controls the particle size distribution