1

Preparation and property control of fine powder in dry processes

Preparation and property control of fine powder in dry processes

Dr. Satoshi AkiyamaManager

Nisshin Seifun Group Inc.

Dr. Carl IshitoPresident

AAAmachine, Inc.

Dr. Satoshi AkiyamaDr. Satoshi AkiyamaManagerManager

Nisshin Nisshin SeifunSeifun Group Inc. Group Inc.

Dr. Carl IshitoDr. Carl IshitoPresidentPresident

AAAmachine, Inc.AAAmachine, Inc.

Event: Powder & Bulk Solids (PTXi) 2008 Seminar: Technical Session 404: Nano powdersPlace: Donald E. Stephens Convention Center, Rosemont IL Date: May 8 (Thu), 2008 10:00 AM -11:00 AM

Event: Event: Powder & Bulk Solids (Powder & Bulk Solids (PTXiPTXi) 2008 ) 2008 Seminar: Seminar: Technical Session 404: Nano powdersTechnical Session 404: Nano powdersPlace: Place: Donald E. Stephens Convention Center, Rosemont IL Donald E. Stephens Convention Center, Rosemont IL Date: Date: May 8 (Thu), 2008May 8 (Thu), 2008 10:00 AM 10:00 AM --11:00 AM 11:00 AM

Ｎ NISSHIN SEIFUN

• Introduction

• Grinding and classification for fine powders

• Synthesis of nano powders by RF plasma method

• Property control of nano powders

• Summary

Contents

2

10.001

100.01

1000.1

10001 10 100 1000

nmµm

Building-up processes

Breaking-down processes

Particle size

Atomization

Preparation of fine powders

Gas phase methods

Liquid phase methodsComminution

Hydrothermal, Hydrolysis, Sol-Gel etc.

Chemical vapor synthesis,Flame pyrolysis, Thermal plasma etc.

Ball mill, Jet mill etc.

Grinding equipment• Ball mill• Mechanical mill (High speed rotor mill) • Jet mill (Fluid-energy mill)

• Inertial classifier• Free vortex type centrifugal classifier

(Centrifugal classifier without a rotor)• Forced vortex type centrifugal classifier

(Centrifugal classifier with a rotor)

Dry grinding and classification

Classification equipment

3

Structure of a mechanical mill

Rotor

Liner

Liner

Rotor

Cross-sectional View (Super Rotor)

Structure of a jet mill

Outlet

Grinding nozzle

Inlet

Comp.air

Grinding zone(1st stage classifying)

Classifying zone(2st stage classifying)Classifying ring

Outlet

Grinding nozzle

Inlet

Comp.air

Grinding zone(1st stage classifying)

Classifying zone(2st stage classifying)Classifying ring

Cross-sectional view (Super Jet Mill)

4

Powder Feed

Air Flow

Air

Classification Rotor

Dispersion Disc

Coarse FractionOutlet

Scroll Casing

Dispersion Blades

Classification Blades

Auxiliary Blades

Balance Rotor

Cross-sectional view (Turbo Classifier)

A forced-vortex-type centrifugal classifier

A new free-vortex-type centrifugal classifier

5

10

5

0

15

0.1 D [µm]1 10

1µm

1µm

Calcium carbonate (CaCOCalcium carbonate (CaCO33))Fine D50 : 1.1µm

Coarse D50 : 3.9µmF [

vol%

]

Fine

Coarse

Performance of the free-vortex-type classifier

Performance of the free-vortex-type classifier

Barium Barium titanatetitanate(BaTiO(BaTiO33))

0.1 1 5Particle diameter [µm]

0

50

100

75

25

Cum

ulat

ive

unde

rsiz

e [%

] Fine fractionYield=63%D50=0.63µmD100=1.2µm Feed

Feed

Fine fraction

Coarse fraction

6

Classification accuracy of the two classifiers

0

0.2

0.4

0.6

0.8

1

1 10 100Cut size [µm]

Cla

ssifi

catio

n ac

cura

cy in

dexκ

[-]

Free vortex type

Forced vortex type

(1) Screw feeder (4) Bag house(2) Mechanical mill (5) Classifier(3) Cyclone (6) Blower

(2)

(5)

(4)

(6)

(3)

(6)

(4)

(3)

(1)

Closed circuit grinding system of mechanical mill and classifier

(1) Screw feeder(2) Super Jet Mill (3) Cyclone (4) Bag house

(2)

(4)

(3)

(1)

Grinding system of Super Jet Mill

Flowsheets of two grinding systems for toner

7

Color toner with polyester resin

Over-grinding for two grinding systems

Energy efficiency for two grinding systems

Color toner with polyester resin

8

Super Jet Mill system with a new classifier

(1) Screw feeder (2) Super Jet Mill (3) New classifier

(4) Cyclone(5) Bag house(6) Blower

(2)

(4)

(1)

Product(Coarse particles)

Fine particles

(3)

(3)

(5)

A new classifier forfine classification

20µm 20µm

Chemical toner(Building-up process)

Median diameter : 5.6 µmCircularity Index : 0.97

Median diameter : 5.4 µmCircularity Index : 0.96

Comparison of chemical and pulverized toners

Pulverized Toner(Super Jet Mill system)

9

Chemical toner Median diameter : 5.6 µmLess than 4µm : 24 pop%

Pulverized tonerMedian diameter : 5.4 µmLess than 4µm : 26 pop%Product yield: 80%

Comparison of chemical and pulverized toners

Nano powders by a themal plasma method

Apparatus for preparation of nano powders

Single component nano powders

Composite of nano powders

What’s a RF(radio-frequency) thermal plasma?Experimental setupFeatures of nano powders by a RF plasma method

Control of particle size

Synthesis of composite nano powdersControl of the particle size and crystal structure

10

Detailed schematic of RF plasma torch

Atomizing probe

Quartz tube

Induction coil (4MHz)

Plasma gas

Raw material+

Atomizing gas

Plasma flame(Max.10,000K)

Plasma in operationQuenching gas

Numerical simulation of a plasma field Temperature contourStreamlines

Induction coils

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

V1=35m/s

V2=10m/s

T1=10,000K

11

Advantages of RF thermal plasma

Large volume and low velocity of plasma flame

ElectrodelessReduce contamination in nanopowders

Oxide, nitride, carbide metal(reduction) etc.

Preparation of composite materialsControl of particle properties(size and crystal structure)

Melt and evaporate raw materials at high throughputs

High chemical reaction atmosphere

Rapid quenching (quenching rate:106K/s)

Manufacturing reactor of nano powders

to Vacuumpump

Plasma gas (Ar and O2 )

RF plasma torch

Chamberfilter

Raw material

Nano particles

Feeder

4MHz-RF power supplyQuenching gas

12

Control of particle size

Nucleation and growth of nano powdersare influenced by

Feed rate of materialsFlow rate of quenching gasReactor pressureGenerator power inputPosition of probe

Control of particle size

adjusting

Dia

met

er [n

m]

Feeding　rate10

100

Al2O3

HighLow

How to control particle size

13

0

20

40

60

80

100D

iam

eter

[nm

] Al2O3

Internal pressure HighLow

How to control particle size

Nano powders prepared by RF plasma

anisotropy

Sphere

Sphere

Sphere

Sphere

Sphere

Sphere

Sphere

Shape(SEM)

30-60nm

30-60nm

50-200nm

50-200nm

30-80nm

30-80nm

30-100nm

10-50nm

Diameter(BET)

CubicCu

CubicNi

MonoclinicY2O3

Cubic+HexagonalSiC

CubicTiN

Cubic(Tetragonal)BaTiO3

TetragonalTiO2

AmorphousSiO2

Crystal System(XRD)

Material

14

TEM image of nano powders

Titania(TiO2)100nm 100nm

Alumina(Al2O3)100nm

Silica(SiO2)

Barium Titanate(BaTiO3)100nm

Nickel(Ni)100nm

Yttria(Y2O3)100nm

Preparation of composite nano powders

Raw material

A

Raw material

B

Compound Solid solution Core-shell

PlasmaPlasma

Feed materials

Control ofReaction field

Composite nano powders

Mixture

15

Examples of composite nano powders

Compositions

1

2

3

4

Y2O3

BaO

MgO

SiO2

1

2

33

2

4

100nm 20nm

(1) Ni

(2) BaTiO3

Mixture Core-shell structure

Other examples of composite nano powders

10-5

10-3

10-1

101

103

105

0 1000 2000 3000 4000 5000

Vap

or p

ress

ure

ratio

[-]

Temperature [K]

Y2O

3/Al

2O

3

Y2O

3/ZrO

2

Comparison of the vapor pressure ratio

Y2O3-Al2O3 systemRaw material has a composition of Y:Al= 3:5.(corresponding to YAG, Yttrium-Aluminum-Garnet)Large difference of vapar pressure values for each material.Y2O3-ZrO2 systemRaw materials have compositions of Y : Zr = 0 : 100, 3 : 97, 10 : 90.Small difference of vapar pressure values for each material.

16

XRD profiles of Y2O3-Al2O3 (YAG) systemIn

tens

ity

10 20 30 40 50 60 70 80 90Angle of 2θ [degree]

Inte

nsity

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

RF plasma

Y3Al5O12 (YAG)

Y2O3 (m)γ-Al2O3

0 1000 2000 3000 4000 5000Temperature [K]

●●

●

▲▲

▲

Y2O3Al2O3

ZrO2

Two crystallographic phase

High crystallinity of Y2O3●

●●

●

●

●

●

●

●●

●

●

●

▲

▲

Boiling point

Melting point

Vapor pressure: Al2O3 >>Y2O3

Mixture of Al2O3 &Y2O3

(Y : Al = 3 : 5)

XRD profiles of Y2O3-ZrO2 system

10 20 30 40 50 60 70 80 90

Inte

nsity

Angle of 2θ [degree]

28 30 32 34 36

10 20 30 40 50 60 70 80 90

Inte

nsity

Angle of 2θ [degree]

28 30 32 34 36

10 20 30 40 50 60 70 80 90

Inte

nsity

Angle of 2θ [degree]

28 30 32 34 36

Y2O3 : 0 %mono + tetra

Y2O3 :10 %cubic

Y2O3 : 3 %tetragonal

The solid solution type is prepared when the materials have a small difference of vapor pressure.

The vapor pressure ratio is a key parameter to prepare the composite nano powders

17

High dielectric constant, Low dielectric loss ・・・

Barium titanate(BaTiO3 ) ceramics

MLCC, Piezoelectric transducers , etc.

Property control of BaTiO3 nano powders

Property control of barium titanate(BaTiO3 )

nano powders by doping Zr

High crystallinity (tetragonal phase)Narrow size distribution and small sizeWeak aggregation

XRD profiles of Ba(ZrxTi1-x)O3 composite

10 20 30 40 50 60 70 80 90

Inte

nsity

Angle of 2θ [degree]

BaTiO3

Ba(Zr0.05

Ti0.95

)O3

Ba(Zr0.10

Ti0.90

)O3

Ba(Zr0.15

Ti0.85

)O3

Ba(Zr0.20

Ti0.80

)O3

Intensities of Zr doped barium titanate nano powders increase with increasing Zr concentration

18

Effect of Zr concentration on crystallinity

5 nm15

20

25

30

35

40

45

0.00 0.05 0.10 0.15 0.20

DBET

DCRY

Ave

rage

size

[nm

]

Zr concentration [-]

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

TEM photo:20% doped BT

1) In order to efficiently prepare fine powders, it is important to use a suitable grinding or classification machine for particle size and characteristics.

2) Using grinding and classifying technologies, it is possible to produce toners similar to chemical ones in particle shape and 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 the composite nano powders

5) The particle size and crystallinity of barium titanate(BaTiO3) nano powders could be controlled by doping Zr.

Summary

19

Thank you very much

for your kind attention.

Thank you very much

for your kind attention.

Ｎ NISSHIN SEIFUN

Experimental conditions (Y2O3-Al2O3 , -ZrO2 system)Experimental conditions (Y2O3-Al2O3 , -ZrO2 system)

Plasma gas 100 slpm(Ar), 20 slpm(O2)

Atomizing gas 10 slpm(Ar)

Plate voltage & current 9 kV, 6A

Power 54 kW

Chamber pressure 50 kPa

Solid content of the solution 20 wt%

Solution feeding rate 10 g/min

Solution

Y(NO3)3, Al(NO3)3(Y : Al = 3 : 5)

Y(NO3)3, ZrO(C2H3O2)2

(Y : Zr = 0 : 100, 3 : 97, 10 : 90)

20

Typical experimental conditions for oxideTypical experimental conditions for oxide

Plasma gas 100 slpm(Ar), 20 slpm(O2)

Atomizing gas 10 slpm(Ar)

Plate voltage & current 9 kV, 6A

Power 54 kW

Chamber pressure 50 kPa

Feed rate of raw material 500 g/min

Experimental conditions (Ca, Zr doped BaTiO3)Experimental conditions (Ca, Zr doped BaTiO3)

Plasma gas 100 slpm(Ar), 20 slpm(O2)

Atomizing gas 10 slpm(Ar)

Plate voltage & current 9 kV, 6A

Power 54 kW

Chamber pressure 50 kPa

Solid content of the solution 20 wt%

Solution feeding rate 10 g/min

Suspension

1µm BaO and TiO2, ZrO(C2H3O2)2

1µm BaO and TiO2, Ca(NO3)2

(Ba : Ca = 100 : 0 ~ 90 : 10)

(Ti : Zr = 100 : 0 ~ 80 : 20)

21

Characteristics of Zr doped BaTiO3

-0.30-0.25-0.20-0.15-0.10-0.050.000.05

0.00 0.05 0.10 0.15 0.20

Shift

of (

110)

[deg

ree]

x [Zr at. fraction]

Solid solution nano powders10 20 30 40 50 60 70 80 90

BaTiO3

BaZrO3

Angle of 2θ [degree]

Inte

nsity 20% Zr doped BT

BT

XRD profiles of (CayBa1-y)TiO3 composite

10 20 30 40 50 60 70 80 90Angle of 2θ [degree]

BaTiO3

(Ca0.05Ba0.95)TiO3

(Ca0.10Ba0.90)TiO3

Inte

nsity

Peak intensities are independent of Ca concentration

22

★ Pure liquid droplet

The vapor pressure decreases by impurities.

Acceleration of the physical condensation

1 4γexpρRs p

p Mp Td

⎛ ⎞= ⎜ ⎟⎜ ⎟

⎝ ⎠

23

6 4γ1 expρπ ρs s p p

p imM Mp M d RTd

⎛ ⎞ ⎛ ⎞= +⎜ ⎟ ⎜ ⎟⎜ ⎟ ⎜ ⎟⎝ ⎠ ⎝ ⎠

1 2 3

61ρπs p

imMp pM d

⎛ ⎞= × +⎜ ⎟⎜ ⎟

⎝ ⎠

Kelvin effect

★ Containing dissolved materials

High crystallinity

BaTiO3 < CaTiO3 << BaZrO3Mp.[K] 1890 2250 2770

m : mass of the dissolved materials

p1 > p2

BTO BTO nanoparticlesnanoparticles

Analysis of nano-BTO

◎ Specific surface area(BET method)

24m2/g (42nm)

Size [μm]

Frequency [%]

0.01 0.1 10

10

20D50 = 48nm

◎ Size distribution

◎ XRD

10 20 30 40 50 60

Intensity

θ2

Cubic

◎ SEM image

100nm

23

Ag Ag nanoparticlesnanoparticles

10 20 30 40 50 60 70 80 90

Intensity

Angle of 2θ [degree]

SSA : 14 m2/gDSSA : 41 nm

DDLS : 79 nm50nm

Alloy Alloy nanoparticlesnanoparticles

Nano alloy

200nm

Ni:Al=1:1DBET=70nm

Intensity

7010 30 50θ2

90

NiAl ●●

●● ●

● ●

200nm

Ni:Ti=1:1DBET=90nm

Intensity

7010 30 50θ2

90

●

●

NiTi ●NiTi2▲

▲●▲ ●

●●

▲

▲