ＮNISSHIN SEIFUN

Preparation and property controlof fine powder in dry processes
Dr.
Dr. Satoshi
Satoshi Akiyama
AkiyamaManagerManager
NisshinNisshin Seifun
Seifun Group
Group Inc.
Inc.
Dr.
Dr. CarlCarl Ishito
IshitoPresident
President
AAAmachine,
AAAmachine, Inc.
Inc.
Event:
Event:
Seminar:Seminar:
Place:
Place:
Date:
Date:

Powder & Bulk Solids (PTXiPTXi)) 2008((PTXi)Technical
Technical Session
Session 404:
404: Nano powders
DonaldDonald E.
E. Stephens
Stephens Convention
Convention Center,Center, Rosemont
Rosemont ILIL
May 8 (Thu), 2008
10:00 AM --11:00
11:00 AMContents• Introduction• Grinding and classification for fine powders• Synthesis of nano powders by RF plasma
method• Property control of nano powders• Summary1Preparation of fine powders
10.001100.011000.11000
110100Particle size
nm1000 µm

Building-up processes
Gas phase methods
Chemical vapor synthesis,
Flame pyrolysis,
Thermal plasma etc.

Breaking-down processes
Atomization

Liquid phase methods
Comminution
Hydrothermal, Hydrolysis,
Sol-Gel etc.

Ball mill, Jet mill etc.

Dry grinding and classification
Grinding equipment• Ball mill• Mechanical mill (High speed rotor mill)• Jet mill (Fluid-energy mill)Classification equipment• Inertial classifier• Free vortex type centrifugal classifier(Centrifugal classifier without a rotor)• Forced vortex type centrifugal classifier(Centrifugal classifier with a rotor)

2Structure of a mechanical millLinerRotor

Rotor
Liner

Cross-sectional View (Super Rotor)

Structure of a jet mill

Grinding zone
(1st stage classifying)

Grinding nozzle
OutletInlet

Comp.airClassifying ring

Classifying zone
(2st stage classifying)

Cross-sectional view (Super Jet Mill)3A forced-vortex-type centrifugal classifier
Powder FeedClassification Rotor
Dispersion Blades
Dispersion DiscClassification Blades
Coarse Fraction
OutletAir
Auxiliary Blades
Scroll Casing
Balance Rotor

Air Flow

Cross-sectional view (Turbo Classifier)A new free-vortex-type centrifugal classifier

4Performance of the free-vortex-type classifier
Calcium carbonate (CaCO3)

Fine D50 : 1.1µm

15

F [ vol % ]Coarse

101µm

Fine

Coarse D50 : 3.9µm

500.11

D [µm]

101µm

Performance of the free-vortex-type classifier

Cumulative undersize [%]Barium titanate(BaTiO3)
10075

Fine fraction
Yield=63%
D50=0.63µm
D100=1.2µm

FeedFeed
Fine fraction

50250Coarse fraction

0.1

15Particle diameter [µm]5Classification accuracy index κ [-]Classification accuracy of the two classifiers
1Free vortex type0.8
0.6

Forced vortex type

0.4
0.2
01

10

100

Cut size [µm]Flowsheets of two grinding systems for toner(1) Screw feeder(4) Bag house(2) Mechanical mill (5) Classifier(3) Cyclone(6) Blower(1) Screw feeder(2) Super Jet Mill(3) Cyclone(4) Bag house

(4)
(4)
(4)

(5)

(3)

(1)
(1)
(6)
(3)

(6)

(3)

(2)
(2)

Closed circuit grinding systemof mechanical mill and classifier

Grinding system ofSuper Jet Mill

6

Over-grinding for two grinding systems

Color toner with
polyester resin

Energy efficiency for two grinding systems

Color toner with
polyester resin

7Super Jet Mill system with a new classifier(3)(1) Screw feeder (4) Cyclone(2) Super Jet Mill (5) Bag house(3) New classifier (6) Blower

(1)

(5)

(4)

(3)

(2)

Fine particles

Product(Coarse particles)

A new classifier forfine classification

Comparison of chemical and pulverized toners
Median diameter : 5.4 µm
Circularity Index : 0.96

Median diameter : 5.6 µm
Circularity Index : 0.9720µm

Chemical toner(Building-up process)

20µm

Pulverized Toner(Super Jet Mill system)

8

Comparison of chemical and pulverized toners
Pulverized tonerMedian diameter : 5.4 µm
Less than 4µm : 26 pop%
Product yield: 80%

Chemical tonerMedian diameter : 5.6 µm
Less than 4µm : 24 pop%

Nano powders by a themal plasma method
Apparatus for preparation of nano powders
What’s a RF(radio-frequency) thermal plasma?
Experimental setup
Features of nano powders by a RF plasma method

Single component nano powders
Control of particle size

Composite of nano powders
Synthesis of composite nano powders
Control of the particle size and crystal structure9

Detailed schematic of RF plasma torch
Raw material+

Atomizing gas
Atomizingprobe
Plasma gas
Induction coil
(4MHz)
Plasma flame(Max.10,000K)
Quartz tube

Quenching gas
Plasma in operation

Numerical simulation of a plasma field
Induction coils

V1=35m/s

Streamlines

Temperature contour

T1=10,000KV2=10m/s

R. Ye,J. Li, T. Ishigaki:Thin Solid Films, 4251, 515(2007)10

Advantages of RF thermal plasma
Electrodeless
Reduce contamination in nanopowders

Large volume and low velocity of plasma flame
Melt and evaporate raw materials at high throughputs

High chemical reaction atmosphere
Oxide, nitride, carbide metal(reduction) etc.

Rapid quenching (quenching rate:106K/s)
Preparation of composite materials
Control of particle properties(size and crystal structure)

Manufacturing reactor of nano powders

FeederPlasma gas (Ar and O2 )Raw material

RF plasma torch
Quenching gas

4MHz-RF power supply

Nano particles
to VacuumpumpfilterChamber11

Control of particle size
Nucleation and growth of nano powders
are influenced by
Feed rate of materials
Flow rate of quenching gas
Reactor pressure
Generator power input
Position of probe
adjustingControl of particle size

How to control particle size

100

Diameter [nm]Al2O310Low

Feeding rate

High12

How to control particle size

Diameter [nm]10080

Al2O360
40200Low

Internal pressure

HighNano powders prepared by RF plasma

MaterialDiameter(BET)

Shape(SEM)

Crystal System(XRD)

SiO2

10-50nm

SphereAmorphous

TiO230-100nm

SphereTetragonal

Y2O330-80nm

SphereMonoclinic

BaTiO330-80nm

SphereCubic(Tetragonal)Ni

50-200nm

SphereCubic

Cu

50-200nm

SphereCubic

TiN

30-60nm

SphereCubic

SiC

30-60nmanisotropy

Cubic+Hexagonal

13

TEM image of nano powders

100nm

100nm

Titania(TiO2)

100nm

Yttria(Y2O3)

100nm

Alumina(Al2O3)

Silica(SiO2)

100nm

100nm

Barium Titanate(BaTiO3)

Nickel(Ni)Preparation of composite nano powders
Raw material

Raw material

AB

PlasmaFeed materials

Control ofReaction field

Composite nano powders

CompoundSolid solution

MixtureCore-shell14

Examples of composite nano powders

1Compositions

223(1) Ni

1 Y2O342 BaO

33 MgO
100nm

20nm

4 SiO2(2) BaTiO3

Core-shell structure

MixtureOther examples of composite nano powders
Y2O3-Al2O3 system
Raw material has a composition of Y:Al= 3:5.
(corresponding to YAG, Yttrium-Aluminum-Garnet)
Large difference of vapar pressure values for each material.

Vapor pressure ratio [-]Y2O3-ZrO2 system
Raw materials have compositions of Y : Zr = 0 : 100, 3 : 97, 10 : 90.
Small difference of vapar pressure values for each material.
105103101

Y2O3/ZrO2-110-3

10

Y2O3/Al2O3-5

1001000

2000

3000

4000

5000

Temperature [K]Comparison of the vapor pressure ratio

15

XRD profiles of Y2O3-Al2O3 (YAG) system●

RF plasma
Y2O3 (m)▲ γ-Al O
2 3Intensity

●

●

●●

●
●
●
●

Two crystallographic phase
High crystallinity of Y2O3

●

●

●

●
▲

Boiling point

Y3Al5O12 (YAG)

Melting point

Intensity(Y : Al = 3 : 5)010203040506070

Angle of 2θ [degree]

80●Y2O3 ▲
Al2O3 ▲●
ZrO2 ▲

90

1000

2000

3000

Temperature [K]

●
4000

5000

Vapor pressure: Al2O3 >>Y2O3
ÆMixture of Al2O3 &Y2O3

Mixture type is prepared when the materials havea large difference of vapor pressure.

28 30 32 34 36

10 20 30 40 50 60 70 80 90

10 20 30 40 50 60 70 80 90

Angle of 2θ [degree]

Angle of 2θ [degree]

Y2O3 : 0 %mono + tetra

Y2O3 : 3 %tetragonal

Intensity

28 30 32 34 36

Intensity

Intensity

XRD profiles of Y2O3-ZrO2 system

28 30 32 34 36

10 20 30 40 50 60 70 80 90

Angle of 2 θ [degree]

Y2O3 :10 %cubic

The solid solution type is prepared when the materials have asmall difference of vapor pressure.
The vapor pressure ratio is a key parameter to prepare
the composite nano powders

16

Property control of BaTiO3 nano powders
Barium titanate(BaTiO3 ) ceramics
High dielectric constant, Low dielectric loss ・・・
MLCC, Piezoelectric transducers , etc.
Property control of barium titanate(BaTiO3 )nano powders by doping Zr
High crystallinity (tetragonal phase)
Narrow size distribution and small size
Weak aggregation

XRD profiles of Ba(ZrxTi1-x)O3 composite

Intensity

Ba(Zr 0.20 Ti0.80 )O 3Ba(Zr 0.15 Ti0.85 )O 3Ba(Zr 0.10 Ti0.90 )O 3Ba(Zr 0.05 Ti0.95 )O 3BaTiO 3102030405060

Angle of 2 θ [degree]708090Intensities of Zr doped barium titanate nano powders
increase with increasing Zr concentration

17Effect of Zr concentration on crystallinity

Average size [nm]45403530DBET
DCRY2520150.000.05

0.100.15

Zr concentration [-]

5 nm

0.20

TEM photo:20% doped BT

The Crystallinity(crystal size) increses and the particle size
decreases as Zr concentration increases.

Summary1) In order to efficiently prepare fine powders, it is important
to use a suitable grinding or classification machine forparticle size and characteristics.
2) Using grinding and classifying technologies, it is possible toproduce toners similar to chemical ones in particle shapeand size distribution.
3) The RF plasma is a useful method for the synthesis ofmany kinds of nano powders.
4) The vapor pressure ratio is a key parameter to prepare thecomposite nano powders
5) The particle size and crystallinity of barium titanate(BaTiO3) nano powders could be controlled by doping Zr.

18

Ｎ

NISSHIN SEIFUN

Thank you very muchfor your kind attention.

Experimental conditions (Y22O33-Al22O33 , -ZrO22 system)
Plasma gas

100 slpm(Ar), 20 slpm(O2)

Atomizing gas

10 slpm(Ar)Plate voltage & current

9 kV, 6A

Power54 kW

Chamber pressure

50 kPaSolutionY(NO3)3, Al(NO3)3(Y : Al = 3 : 5)
Y(NO3)3, ZrO(C2H3O2)2(Y : Zr = 0 : 100, 3 : 97, 10 : 90)

Solid content of the solution

20 wt%

Solution feeding rate

10 g/min19

Typical experimental conditions for oxide
Plasma gas

100 slpm(Ar), 20 slpm(O2)

Atomizing gas

10 slpm(Ar)Plate voltage & current

9 kV, 6A

Power54 kW

Chamber pressure

50 kPaFeed rate of raw material

500 g/minExperimental conditions (Ca, Zr doped BaTiO33)
Plasma gas

100 slpm(Ar), 20 slpm(O2)

Atomizing gas

10 slpm(Ar)Plate voltage & current

9 kV, 6A

Power54 kW

Chamber pressure

50 kPaSuspension

1µm BaO and TiO2, ZrO(C2H3O2)2(Ti : Zr = 100 : 0 ~ 80 : 20)
1µm BaO and TiO2, Ca(NO3)2(Ba : Ca = 100 : 0 ~ 90 : 10)

Solid content of the solution

20 wt%

Solution feeding rate

10 g/min20

Characteristics of Zr doped BaTiO3

20% Zr doped BTBTBaTiO3BaZrO3

Shift of (110) [degree]

Intensity

0.05
0.00
-0.05
-0.10
-0.15
-0.20
-0.25
-0.30
0.00

0.05

0.10

0.15

x [Zr at. fraction]

0.20

Solid solution nano powders

10 20 30 40 50 60 70 80 90

Angle of 2θ [degree]

XRD profiles of (CayBa1-y)TiO3 composite

Intensity(Ca0.10Ba0.90)TiO3(Ca0.05Ba0.95)TiO3BaTiO3102030405060708090

Angle of 2θ [degree]
Peak intensities are independent of Ca concentration21

Kelvin effect★ Pure liquid droplet⎛
6imM ⎞p1 = p2 × ⎜ 1 +⎜ M ρπd 3 ⎟⎟sp ⎠⎝⎛ 4γM ⎞p1= exp ⎜⎜ ρRTd ⎟⎟psp ⎠⎝★ Containing dissolved materials

p1 > p2⎛ 4γM ⎞p2 ⎛6imM ⎞exp ⎜= ⎜1 +⎟3⎜ ρRTd ⎟⎟ps ⎜⎝ M s ρπd p ⎟⎠p ⎠⎝m : mass of thedissolved materials

The vapor pressure decreases by impurities.
High crystallinity
Acceleration of the physical condensation

Mp.[K]BaTiO3 < CaTiO3 << BaZrO3
1890
2250
2770

BTO nanoparticles
Analysis of nano-BTO◎ Size distribution
Frequency [%]◎ SEM image

20
D50 = 48nm
1000.01◎ Specific surface area(BET method)

24m2/g (42nm)

1

◎ XRD
CubicIntensity

100nm

0.1
Size [μm]1020302θ

40506022

Ag nanoparticlesytsinetnI

102030405060708090Angle of 2θ [degree]

SSA : 14 m2/g
DSSA : 41 nm
DDLS : 79 nm

50nm

Alloy nanoparticles
Nano alloy
Ni:Al=1:1

Ni:Ti=1:1

DBET=70nm

DBET=90nm

200nm●

NiTi ●
NiTi2 ▲

Intensity

Intensity

NiAl ●

200nm●

1030502θ

▲
▲●●
● ▲

●

●
●

●

70●

90

1030502θ

●

●
▲

70

9023