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 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.