1
2003. 10
Byoung-Kee Kim
Korea Institute of Machinery and Materials,
Application of Nanostructured powders synthesized by new chemical processes
Characteristics of Nanopowder Materials
KIMM Korea Institute of Machinery and Materials
- Enhanced catalytic properties- Enhanced absorption ability- Capilary Condensation
- Enhanced catalytic properties- Enhanced absorption ability- Capilary Condensation
Surface Effect
- Appearance of New Phases- Decrease of Melting Point- Polycrystallization of Single Crystal- Enhanced Scattering Effect of Waves
- Appearance of New Phases- Decrease of Melting Point- Polycrystallization of Single Crystal- Enhanced Scattering Effect of Waves
Bulk Effect
- Electric and heat transfer - Compressability- Solid state reactivity
- Electric and heat transfer - Compressability- Solid state reactivity
Interaction between Nanopowders
~3As6As10NiCatalytic Property
(As : standard Activity)
700℃~200℃~1000℃200220
NiW
SinteringTemperature
20mK2.0mK100AgHeat Transfer
3.4K5.3K90AlTransition
Temperature ofSuperconductivity
2~5%95%100AuLight Absorption(6~10㎛)
1300K430K
933K370K
3040
AuIn
MeltingPoint
~470Oe1030Oe50FeMagneticProperty
Micro-materials
Nano-materials
Size(Å)MaterialsProperty
2
Application Field of Nanopowder Materials
KIMM Korea Institute of Machinery and Materials
ElectronicOptical
ElectronicOptical MagneticMagnetic
StructuralStructural OthersOthers
◆ Optoelectronic devices◆ Passive electronic
devices◆ IC substrate◆ Thermistor and varistor◆ Piezoelectric actuators◆ CMP
◆ Advanced tones◆ Diagnostic contrast agents◆ Ferrofluids◆ Magnetic Recording◆ Magnetic Refrigerator
◆ Cutting tool ◆ Die
◆ Coating
◆ Abrasive components
◆ Catalysts◆ Chemical sensors◆ Energy storage devices◆ Pigments◆ Membranes
Research of Nanopowders in KIMM
KIMM Korea Institute of Machinery and Materials
Chemical Sensor, Membranes, Filter, TiO2 photocatalystsChemical/Catalytic
Materials
Thermistor, Varistor, Piezoelectric actuator Cu-Al2O3 electrode, W-Cu heat sink
Electric/Electrode Materials
Ferrofluid, Magnetic refrigerator, Recording media, Hard/Soft Magnets, Fe/Co magnetic materials, Nd-Fe-B hard magnet
Magnetic Materials
Abrasives, Cutting tools, CMP, Wear-resistant componentsWC-Co hard materials
Tool Materials
MaterialsArea
3
Mechanical Properties of WC/CoMechanical Properties of WC/Co
Chemical compositions(contents of Co)Particle size of hard phase(WC)Homogeneity of WC/Co (mean free path)
Chemical compositions(contents of Co)Particle size of hard phase(WC)Homogeneity of WC/Co (mean free path)
Reduction of WC size Decrease of mean free pathReduction of WC size Decrease of mean free path
Hardness Compressive StrengthTRS Strength Wear Resistance
Hardness Compressive StrengthTRS Strength Wear Resistance
Key for high mechanical properties Fabrication of very fine WC Higher homogeneity of WC and Co phases
Key for high mechanical properties Fabrication of very fine WC Higher homogeneity of WC and Co phases
KIMM Korea Institute of Machinery and Materials
Manufacturing of WC/Co AlloysManufacturing of WC/Co Alloys
APT powder
Calcinations
Reduction
Carburization
Milling(+C)
Milling(+Co)
W, Co metalorganics
Evaporation/Carburization
WC, WC-Co
W,Co chlorides
Spray drying
Reduction/Carburization
Reduction/Carburization
Milling(+C)
Removal of Chlorides
Solid Phase Process Liquid Phase Process Gas Phase Process
G.S. > 300nm G.S. > 100nm
G.S. < 30nm
Korea Institute of Machinery and MaterialsKIMM
4
Temperature(℃)400 800 1200
W2(C,O)
W
W2C
WC
H2/He
He
HeH2/HeH2/CH4
H2/CH4
20nm
10nm
• low pressure(10-3atm)• size: 5nm• low pressure(10-3atm)• size: 5nm
Tem
pera
ture
(℃)
Concentration of Methane
WC
WC+W2C
W2C + W
WC +W2C+ W
Low C
High C
800
1000
1200
1400
sccm 20 40 60 80 100 120 140
Total : 600sccm
n-WC powder n-WC powder
KIMM Korea Institute of Machinery and Materials
Coating of n- WC,Co powder
Carbon coating WC powder
• WC powder: 4nm• WC powder: 4nm
4nm
Oxide coating Co, Fe powder
• Core(metal)/Shell(Oxide) •Oxide shell : 3nm)• Core(metal)/Shell(Oxide) •Oxide shell : 3nm)
5 nm
Fe
Fe oxide
Co
Co oxide
0 200 400 600 800 1000100
104
108
112
116
Co oxidationWei
ght C
hang
e(%
)
Temperature(oC)
WC(C:10.5%)/CVC WC(C:5.78%)/CVC WC-10Co/TCP Taegutech
KIMM Korea Institute of Machinery and Materials
5
10 9 8 7 6 5
0
100
200
300
400
500
600
700
Loa
d(kg
f)
Displacement(mm)
10nm-1.0% 10nm-2.0% 100nm-1.0% 100nm-2.0%
2.23.09100nmC
1.852.02100nm(granule)B
0.7718.420nmA(NRL)
A.D.(g/cm3)
BET(m2/g)
Power sizetype
Compactabilityof n-WC powderCompactabilityof n-WC powder
Compact desity 47%
Rearrange of particles
KIMM Korea Institute of Machinery and Materials
Sinterbility of n-WC/Co powder
Solid sintering temp.
• WC(20nm)+Co(20nm) : 835oC• WC(20nm)+Co(100nm) : 890oC• WC/Co(100nm) : 1010oC• WC/Co(200nm) : 1070oC
• WC(20nm)+Co(20nm) : 835oC• WC(20nm)+Co(100nm) : 890oC• WC/Co(100nm) : 1010oC• WC/Co(200nm) : 1070oC
835oC
890oC
1010oC1070oC
835oC
890oC
1010oC1070oC
20nm→2㎛( x 100)
100nm→1㎛( x 10)
WC/Co(20nm)
WC(20nm)/Co(100nm)
WC/Co(200nm)
WC/Co(100nm)
• sintering temp: WC size(1070→835oC)Co size (890→835oC)
• abnormal grain growth (100 times,)Grain growth inhibitors
KIMM Korea Institute of Machinery and Materials
6
Plasma sintering/grain growth inhibitorPlasma sintering/grain growth inhibitor
WC-10Co-0.6VCround, 70nm( x 4)
WC-10Co-0.6VCround, 70nm( x 4)
WC-10Cofacetted shape 1㎛ (x 50)
WC-10Cofacetted shape 1㎛ (x 50)
Conventional WC-10Co
Nano. WC-10Co
• High Dislocation Density• Stacking Faults
• Dislocation free WC grains• Twins in WC grains
Plasma sintering
KIMM Korea Institute of Machinery and Materials
Properties of Nanostructured WC-Co Alloy
>1.0㎛
7
Nano sized Fe and Co Magnetic Materials
KIMM Korea Institute of Machinery and Materials
Magnetic Fluid : Magnetite(Fe3O4)
Saturation Magnetization of Fe = 2 times of that of Fe3O4Coercivity ; proportional to inverse of particle size (Hc = a+b/D)
Synthesis of nano-sized Fe ⇒ High performance magnetic fluid materials( Saturation Magnetization : 1500emu/cm3, Coercivity : 3000Oe)
Development of Fe based nanopowder for magnetic fluidsby Chemical Vapor Condensation
Development of Fe based nanopowder for magnetic fluidsby Chemical Vapor Condensation
KIMM Korea Institute of Machinery and Materials
KIMM30 35 40 45 50 55 60 65 70 75 80Co nanoparticles (fcc-type)
Fe nanoparticles (bcc-type)
Inte
nsity
(arb
. uni
t)
2 θ
CoFe
CoreCrystalline Fe
CoreCrystalline Fe Shell
Crystalline Fe oxides
ShellCrystalline Fe oxides
Microstructures of Fe Nanoparticles
5 nm
8
KIMM Korea Institute of Machinery and Materials
KIMM-10 -8 -6 -4 -2 0 2 4 6 8 10
(d)
(c)
(b)
(a)
Rel
ativ
e Tr
ansm
issi
on
Velocity (mm/s)
Samplesα -Fe(%)
Bulk Middle
Super-paramagnetism
(%)Fe3O4(%)
Mean size(nm)
(a) 2 0 98 0 5.39(b) 20 5 75 0 ~7.0(c) 34 24 21 21 10.32(d) 70 0 10 20 ~12.0
Superpara- Ferro-Ferro-Superpara-
(a) (b) (c) (d)
Superpara-
Ferro-
Mössbauer spectroscopy of Fe nanoparticles
KIMM Korea Institute of Machinery and Materials
KIMMCoreCrystalline Fe-Co
CoreCrystalline Fe-Co
ShellCrystalline Fe and Co oxides
ShellCrystalline Fe and Co oxides
Twin structureTwin structure
Microstructures of Fe-Co nanoparticles
9
KIMM Korea Institute of Machinery and Materials
KIMM30 35 40 45 50 55 60 65 70 75 80
Carrier gas: Ar + 6%O2
Carrier gas: He
Carrier gas: Ar
2 θ
BCC Co+ HCP CoBCC CoBCC Co
++ HCP CoHCP Co
BCC CoBCC CoBCC Co
Co oxideCo oxideCo oxide
Phases of Co nanoparticles with carrier gases
KIMM Korea Institute of Machinery and Materials
KIMMDifferent phases with different Co contentDifferent phases with different Co content Saturation magnetization reaches
highest value near 40 wt% CoSaturation magnetization reaches
highest value near 40 wt% Co
10 15 20 25 30 35 40 45 50 55 6020
40
60
80
100
120
M
s (e
mu/
g)
Co content3 0 4 0 5 0 6 0 7 0 8 0
2θ
Inte
nsity
(arb
. uni
t)
F e -4 7 C o
F e -5 0 C o
F e -4 0 C o
F e -3 4 C o
F e -1 0 C o
F C C -F e (C o )
B C C -F e (C o )
Phases and saturation magnetization
10
Nanostructured TiO2 photocatalytic materials
KIMM Korea Institute of Machinery and Materials
Decrease of particle size- Improved UV scattering- Enhanced photocatalytic activity- Improved gas sensing property- Enhanced opto-electronic property
Synthesis of nano sized TiO2 powders by Chemical Vapor Condensation process (Non-Agglomerated 10nm powder)
KIMM Korea Institute of Machinery and Materials
KIMMMicrostructure of Nano-sized TiO2 Powder
Anatase Rutile
20 25 30 35 40 45 50 55 60
Inte
nsity
2θ
size : 10nmloose agglomeratesphases : Anatase + Rutile (
11
KIMM Korea Institute of Machinery and Materials
KIMMPhase Change Depending on Powder Size
[100] zone axis(110) type planes
Anatasea=3.75Å, c=9.51Å
Anatasea=3.75Å, c=9.51Å Rutile~60nm
Rutile~60nm
Nanostructured W-Cu heat sink materials
KIMM Korea Institute of Machinery and Materials
Poor sinterability due to the negligible solid solubility between W and Cu
Conventional Process- Infilteration : Low thermal & electric conductivity
due to the addition of sintering activator- Liquid phase sintering : Low properties due to larger W sizeDevelopment of new process to achieve high density nanostructured W/Cu materials, using nanostructuredpowder (W : 60nm)
12
Microstructures of W/Cu Alloys
Mixing methodW:0.51%, Cu:20%
Thermochemical method(W-20wt%-0.5wt%Co)
Mechano-thermochemical method(II)Reduced powder (200C/1h+700C/1h)
Mechano-thermochemical method(I)Burnt out powder, Two-reduction step
KIMM Korea Institute of Machinery and Materials
Sinterabilty of Nanostructured W/Cu Powders
1000 1100 1200 130020
30
40
50
60
70
80
90
100
Green density
Sintering density Burnt out powder (process I) Reduced powder (process II) Metal mixed powderGreen density Burnt out powder Reduced powder Metal mixed powder
Cu melting pointGreen density
Rel
ativ
e de
nsity
(%)
Sintering temperature (oC)
KIMM Korea Institute of Machinery and Materials
13
Comparison of Thermal Properties
7.257.887.806.5
(6.8-7.6)5.4
(6.0-7.0)8.0(8.1-8.9)6.5 (7.2-8.0)
ThermalExpansionCoefficient(ppm/K)
221.3245.8233.0170
(180-210141
(180-210242
(180-210207
(180-210)
ThermalConductivity
(W/mK)
223.2223.2223.2300.0294.5240.1223.2Specific
Heat(J/Kg·K)
15.16-L14.85-T
15.43-L15.17-T
15.48-L15.17-T
9.819.8914.6315.94Density(g/㎠)
W-20CuKIMM750-4
W-20CuKIMM700-8
W-20CuKIMM700-8
Mo-20CuThermkon
-70M
Mo-15CuThermkon
-65M
W-20CuThermkon
-83
W-20CuThermkon
-76
KIMM Korea Institute of Machinery and Materials
Prospect of Nanopowder Materials
KIMM Korea Institute of Machinery and Materials
Thin Films
Electro-opticalDevice and
Ferroelectrics
SuperhardMaterials
Drilling, Miningand Machine
Tools
ProtectiveCoatings
TransportationEnergy, Chemical
Industries
AdvancedNanocomposites
EnergyAnd Aerospace
Industries
Ceramics Cermet Metals
5 10 15Years