STUDY OF INTERFACIAL PHENOMENA BETWEEN

LIQUID IRON AND SLAG SYSTEM BY USING ELECTROSTATIC FURNACE (ELF) ON ISS

Masahito Watanabe Gakushuin University

10th Japan-Korea Joint Seminar on Space Environment Utilization Research (Korea University, Seoul, Korea, September 12~13, 2013)

Introduction

Oxide (Slag) melt

Steel melt

Container-less approach for understanding interfacial phenomena between molten steel and slag system using core-shell structure droplet

The research contributes the precise process control for the high advantage steels.

Levitated by Electrostatic levitation furnace (ELF) in ISS

1

Continuous casting using mold flux Nozzle

Mold flux

Cast steel

Mold

Solid flux

Prevent pulling down of flux particle

Continuous cast machine

2

To prevent drop-off slag particles into molten steel, keeping high interfacial tension between molten steel and slag is necessary during contentious cast processing.

Interfacial tension measurements by X-ray radiography

3

Slag

Fe

Slag

Fe Slag

Fe

Fe

Inte

rfac

ial

Ener

gy

Al c

onte

nt in

Fe

32.

2.

3/2

3/4

OAlSiSiOAl

FeLiqin

FeLiqin

+=

+

P.V. Riboud and L.D. Lucas : Can. Metall. Quar., 20 (1981), 199-208.

3

3

Interfacial energy of compound drop

W =σ oAo +σ12Ai Prof. I. Egry (DLR), private communication.

ω o

2 =(l −1)l(l + 2)σ o

ρoRo3

Surface free energy:

Pure surface frequency:

・Immiscible liquid droplets

Ri

µo ,ρo

µi ,ρi

Ro

σ 12

σ o

Interface oscillation frequency: ω ±2 =ω0

2 × f± (σ o σ 12 , Ri Ro,Δρ)

4

Surface oscillation frequency of immiscible Cu-Co droplet under micro-G

ω o

ω−

ω+

5

Surface oscillation analysis for molten Fe/slag system

ω o

2 =8σ o

ρoRo3

Surface oscillation frequency of outside fluid

Normal mode frequency of droplet without viscosity

Ri

µo ,ρo

µi ,ρi

Ro

σ 12

σ o

ω±2 =ωo

2K±

τ 8

σ2

(1+ Δρ)τ 10 + 2 3Δρ⎛⎝⎜

⎞⎠⎟

K± =

12

σmi

τ 3 +moτ

3

σ⎛

⎝⎜⎞

⎠⎟± 1

4σmi

τ 3 −moτ

3

σ⎛

⎝⎜⎞

⎠⎟

2

+1

mi = (1+ Δρ)τ 5 − Δρτ 5 , mo =

35τ 5 + 2

5τ 5

τ =Ro

Ri, σ=

σ o

σ12

, Δρ = 35ρi − ρo

ρo

ω i2 =

24σ12Ri3(2ρo + 3ρi )

Interface oscillation frequency of inside fluid

6

Numerical simulation of droplet oscillation of Fe-slag drop

[kg/m3] [kg/m3] [Pa･s]

[Pa･s] [m] [m] [N/m] [N/m] 2848 7030 0.214 0.0055 0.003475 0.002149 0.45 1.306

Initial long radi., a0 [m] Initial short radi., b0 [m] Initial ration, a0/b0 Slag(Outside) 0.003924 0.003270 1.2 Iron(Inside) 0.002427 0.002022

Thermophysical properties and equilibrium shape of drop

Fe

Slag 1/67倍倍速速

σ o

σ 12

Riµo ,ρo

µi ,ρiRo

ρo µo ρi µi Ro Ri σ o σ 12

1/67倍倍速速

7

Surface oscillation of molten Fe-slag drop by numerical simulation

8

0 20 40 60 80 100

1E-6

1E-5

1E-4

1E-3

b：slug

周波数

振幅

-240

-120

0

0 20 40 60 80 100周波数

位相

f+ =ω+

2π

f+ =

ω−

2π

0 20 40 60 80 100

1E-6

1E-5

1E-4

1E-3

b: iron

周波数振幅

-260

-130

0

0 20 40 60 80 100周波数

位相

fi =

ω i

2π

Frequency (Hz) Frequency (Hz)

Inte

nsity

(a.u

.)

Inte

nsity

(a.u

.) In

tens

ity (a

.u.)

φφ

Surface oscillation frequency

Interface oscillation frequency

ω+2 =ωo

2K+

τ 8

σ1

(1+ Δρ)τ 10 + 2 / 3Δρ f+ =

ω +

2π= 56.1Hz,

σ =0.59 (σ o σ 12 = 0.34), Δρi = 0.88 ((ρi − ρo ) ρo = 1.47), fo =

ω o

2π= 27.6Hz

f− =ω−

2π= 25.3Hz

ω−

2 =ω o2K−

τ 8

σ1

(1+ Δρ)τ 10 + 2 / 3Δρ

Surface oscillation frequency of molten Fe-slag drop

ω i2 =

24σ12Ri3(2ρo + 3ρi )

fi =ω i

2π= 54.6Hz

9

Interfacial tension between molten Fe and slag

Effect of oxygen at interface

σ i =σ i0 − RTΓ0 1+ K0aO( )

σ i

0 ⇔σ Fe ,σ slag

How does the relationship between interfacial tension and surface

tensions?

10

Electromagnetically levitated Ag melts covered by B2O3 melts under ground conditions

(a) Before Ag melting

Ag

B2O3

(b) After Ag melting

(c) After Solidification   We cannot make core-shell structure of liquid metal covered by oxide melts on ground conditions.

We need microgravity conditions!

11

Conclusion

12

We start to study of interfacial phenomena between molten Fe and slag by containerless approach using electro-statistically levitated core-shell structure droplet . We clarify that interfacial tension can be obtained from surface oscillation frequency. ISS experiments will star from late 2014.

Acknowledgments

13

Prof. T. Ishikawa, JAXA Prof. T. Tanaka, Osaka Univ. Prof. T. Tsukada, Tohoku Univ. Prof. S. Ozawa, Chiba Inst. of Tech. Prof. H. Fukuyama, IMRAM, Tohoku Univ. Prof. A. Meyer, German Aerospace Center(DLR) Dr. F. Kargl, German Aerospace Center(DLR), Prof. H. J. Fecht, Ulm University Prof. J. Lee, Korea University Rrof. R. W. Hyers, University of Massachusetts Dr. T. Matsushita, Jönköping University Prof. A. E. W. Jarfors, Jönköping University

All members of collaboration team:

Technical and financial support by JAXA.