1

Improvement of compatibility of liquid metals Li and Pb-17LI

Masatoshi KONDO, Minoru TAKAHASHI b), Teruya TANAKAa), Tsisar Valentyn c) and Takeo MUROGA a)

 Tokai university, Japan, a)National Institute for Fusion Science a) b) Tokyo Institute of Technology, Japanc) Physico-Mechanical Institute of National Academy of Sciences of Ukraine, Ukraine

ISLA2011

2

Background -1Fusion blanket

KOREA 　 HCML-TBM　(2008)Li/RAFMDr.KIM　et　alJapan　(2003)

molten　salt　Flibe/RAFM　Dr.Sagara　et　al.,　FED

India 　 TBM 　 (2009)Pb-LI ・ solid　breeder/RAFM　Dr.Kumar　et　al　FED

Liquid breeder Structure

Lithium 　Ｌｉ

Lead lithium Pb-17Li

Flibe LiF-BeF2

Vanadium alloy

Ｓ i Ｃ

ＯＤＳ

Japan

JapanRussia

Korea

USARAFM

EuropeIndiachina

Toward high temperature

Pure metal

Molten salt

Alloy

Coating(MHD, Ttritum .etc)

Al2O3

Er2O3(DiP ・ＭＯＣＶＤ )

Nitride treatment

Er2O3(DiP ・ＭＯＣＶＤ )

Japan　(2003)　liquid　metal　Li/vanadiumDr.Muroga　et　al.,　FED　

3

Background -2(Structural material)

Corrosion of RAFM steel in liquid metals

Chemical reaction of steel’s base metal (Fe), alloying elements (Cr, W) and carbides with liquid metals

wt% Cr W C Mn Other

Fe

ＪＬＦ -1

９ 1.94

0.09

0.49

V:　0.2

balance

Chemical composition (wt%)

Reduced activation ferritic martensitic steel is candidate structural material of blanket.

1 ０ µm

Prior austenite grain boundary

Packet boundary

Lathboundary

Somesub grains

Blockboundary

4

Background -3 (Liquid breeders)

M.P.

(K)

Thermal conductivity

(W / (m x K))

Density

(kg/m3)

Viscosity

(mPas)

Li Alkali metal 453.7 53.7 (800K) 481 (800K) 0.344 (800K)

Pb-17Li Heavy metal 508 9568 (800K) -

Flinak

(LiF-NaF-KF)

Molten salt 727 1.2 2146 (800K) 4.1 (900K)

Flibe

(LiF-BeF2)

Molten salt 732 1.2 1993 (800K) 7.5 (800K)

FlinakLiquid Lithium

Li+

Free electron　

High thermal conductivity in liquid metal High chemical stability of molten salt

Li+ F-+

Already stable state by ion bonding

Major characteristics of liquid breeders

5

Purpose

Purpose of the present study is follows;

- Establish corrosion test technology for liquid Li and Pb-Li

- Make clear the corrosion characteristics of RAFM JLF-1 steel in the liquid metals

- Make clear the corrosion of coating in the liquid metals

- Modeling of the corrosion of RAFM steel in the liquid metals

6

Experimental procedure (1)

Fe Cr W Ni

Li 0.85 0.12 0.31 0.8 Nitrogen: 65

Pb-17Li 2.2 0.17 0.52 1.3 -

Pb-17Li provided by santoku coop.

Temperature 　 600ºC Time(hours) Re for mixing - Material

LiStatic 30-250-750

High purity, Li3N dopeLi2O dope, C dope

JLF-1Er2O3 coat

Flowing 250 2859 High purity JLF-1

Pb-17LiStatic 250-3000 High purity

JLF-1Er2O3 coat

Flowing 250 18512 High purity JLF-1

Initial impurity of liquid metals (wppm)

Experimental condition 　

Carbon Li2O Li3N

7

Experimental procedure (2)

Influence of flow

3cc

100cc

Fixed specimen

Width of impeller 　 33 ｍRotation speed 100 rpmVelocity around specimen 　 v=π ｄｎ =0.17cmRe number for mixing 　

2nd

=Re

48mm

Static test(Simple immersion)

Flowing test(Mixing vessel)

(c) Impurity analysis of liquid breeders by ICP-MS　 ( Fe, Cr, W, non metal impurity)(To investigate mass balance between loss in specimen and increase of metal impurity in melt )

(b)SEM/EDX analysis for surface and cross section(To evaluate the metallurgical change of steels)

(a) Weight loss measurement(To estimate the corrosion (loss) rate)

Analysis of corroded specimen

Take out sample Li immersion

at 350ºCAcetone

Immersion to ethanol

Acetone

Immersion to ethanol

Cleaning procedure for tested specimen

Specimen in Li

Specimen inPb-Li

9

Experimental results (Mass loss of specimen by corrosion in Li)

- The influence of non-metal impurity (i.e. nitrogen and oxygen) in liquid Li was large on the corrosion loss.

- The Influence of oxygen in Li on the corrosion was newly found.)

-2

0

2

4

6

8

10

12

14

Li(+0.8wt%Li2O)

(Static)750-hour

Li(+0.5wt%Li3N)

(Static)250-hour

Li(Pure)(Static)

250-hour

Li(Pure) (Flow)

250-hour

Li(+3.7wt%C)

(Static)250-hour

Wei

ght

loss

of

spec

imen

s (g

/m2 )

Experimental results (Lithium)

20 hour 120 hour 250 hour

Ｌｉ +0.5wt%Li3N 　 nitrogen dope (Cr dissplution)

1 ０ µm 20µm 20µm

選択的

250 hour

Phase transformation

BCTa a

c

a a

a

BCC

C Fe

Phase transformation

Initial

122 hour 780 hour287 hour

Ｌｉ +0.8wt%Li2O 　 oxygen dope (Cr dissolution)

Ｌｉ +3.7wt% Ｃ　carbon dope

1 ０ µm 1 ０ µm 1 ０ µm

Phase transformation

No phase change

11

0

20

40

60

80

100

0 10 20 30Er

conc

entr

atio

n in

Li

uni

t: w

ppm

(IC

P-M

S)

0 10 20 30 exposure (hour)

600ºCEr2O3/JLF-1

Surface color was black after the corrosion test though the color was metallic luster before the test.

２０ µm

normal

Corroded(Er-Cr rich)

Peeling off

ＳＥＭ

Crack

-0.10

0.10.20.30.40.50.60.70.80.9

0 50 100 150 200 250Th

erm

al l

inea

r ex

pan

sio

n %

Temperature (ºC)

Li

JLF-1

Er2O3

Corrosion of Er2O3 coating in Li

The oxide itself might be chemically stable in the liquid breeders. The damage was possibly made by a large difference of the thermal expansion ratio between adhered Li and the coating during a heat up and a cool down procedure of the corrosion test when the Li was solidified.

12

Summery for corrosion in Li

- Nitrogen dissolved in Li has big influence on the compatibility. It was newly found that oxygen in Li can increase the corrosion of steel. The nitrogen and oxygen dissolved as non-metal impurity in Li must be removed before the use. Carbon in Li can suppress the the depletion of carbon in the steel.

- The issue for the coating of liquid blanket is the peeling of the coatings in the liquid metals.

13

Experimental results (Weight loss of specimen in Pb-Li at static condition)

Corrosion was suppressed when the metal element, i.e. Fe and Cr, in Pb-17Li was saturated..

Experimental results (Pb-17Li)

600oC 750 hours

High mag. (x3000)

20µm

5µm

Low mag. (x1000)

600oC 3000 hours

20µm

5µm

High mag. (x3000)

Low mag. (x1000)

The corrosion in JLF-1 was selective attack to some boundaries of microstructure.

15

Experimental results (Corrosion of Er2O3 coating in Pb-Li)

20µm20µm20µm

Er

Fe

CrCou

nt n

umbe

r

Resin Pb-Li Steel matrix

0 20 40 60 80

Depth (µm)

The oxide itself might be chemically stable in the Pb-Li. The damage of the coating was possibly made by a large difference of the thermal expansion ratio between adhered Pb-Li and the coating during a heat up and a cool down procedure of the corrosion test when the Pb-Li was solidified.

0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600Temperature (ºC)

Th

em

al l

ine

ar

exp

an

sio

n (

%)

Li

Pb

JLF-1

Er2O3

16

Flowing Li 　

Internal　diffusion　of　liquid　metals

(FAC) (Erosion　corrosion)

10µm

Erosion- corrosion was caused by peeling of subgrains after corrosion on surface.

Flowing Pb-17Li

10µm

Experimental results (Corrosion in flowing Li and Pb-Li)

17

Corrosion modeling

Li (65wppm nitrogen) Pb-17Li Pb

Solubility(Cs)

wppmMolppm

Fe - * 47 (600ºC) ~<145> 34 (600ºC) <126>

Cr52.4 (800 ºC) <7>~94.3 (600ºC) <12.6>

10 (500ºC) <40> 1 (600ºC) <3.7 >

))V

hStexp(ρVCs(1Δm

C)-(CshJdt

dC

S

Vρ

))V

hStexp(Cs(1C

Transient of metal impurity in liquid breeders

Corrosion ratio

Mass loss of specimen by corrosion

Concentration of metal in liquid breeders

Mass balance between increase of metal impurity in liquid breeders and corrosion ratio of specimen

18

Mass transfer model in corrosion (Li)

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

0 100 200 300 400 500 600 700 800

Wei

ght

loss

per

uni

t are

a (g

/m2 )

Exposure time (hours)

Test A

Test B

Test C

Test D

Different corrosion device

600oC (Li)

Different geometrical factor of corrosion systemVolume / corrosion surface area

V/S

Large

Small

19

600oC (Pb-Li)

Mass transfer model in corrosion (Pb- Li)

20

Summery

Major conclusions are follows;

- Corrosion test technology for liquid Li and Pb-Li was established.

- The corrosion characteristics of JLF-1 in static Li and Pb-Li were investigated. Then, we started to study about the corrosion in flowing condition.

-Modeling of corrosion of JLF-1 in Li and Pb-Li was started.

- Fundamental corrosion characteristics of anti corrosion coating in liquid Li and Pb-Li was studied. The issue is the peeling off of the coatings in liquid metals.

21

22

Corrosion of Fe-Al coating in liquid Pb-Li

10µm

Fe-Al coating

剥離 316LPb-Li

Pb

O

Fe

Al

ＳＥＭ After 500- hour immersion in Pb-17Li at 600 degree C

Coating it self was chemically stable in liquid Pb-Li.

However, the peeling off is issues for the coating.

Now, study on metal plating technology is under going.

23

Background -4Corrosion phenomena

Solubility of metal elements and chemical potential of non- metal impurity in liquid metals are important parameters which determine the corrosion.23

Compatibility

Liquid metal corrosion

Formation of corrosion products

(Carbides, oxides, nitrides, hydrides and so on)

-Dissolution of steel element into liquid metals-Diffusion of metal elements of liquid metal into steel matrix

Determined by alloying process

Determined by chemical potential of non-metal impurity

All liquid metals especially heavy liquid metal

Pb, Pb-Bi

Li, Na, K, Pb-Li(?)

GB attack Erosion- corrosion

Peering of corrosion products

FAC

At flowing condition

At flowing static condition

24

0.0001

0.01

1

100

10000

700 800 900 1000 1100 1200 1300

Sol

ubili

ty o

f F

e an

d C

r in

Lith

ium

(w

ppm

)

Temperature of Lithium (K)

Cr in Li (Nitrogen 150wppm)[12]

Solubility of Cr in Li (Nitrogen <10wppm) [11 ]

Solubility of Fe in Li (Nitrogen 500wppm)[11]

Solubility of Cr in Li (Nitrogen 200wppm) [11]

Solubility of Fe in Li (Nitrogen <10wppm) [11 ]

Solubility Cr in Li (Nitrogen 790wppm)[12 ]

Solubility of Cr in Li (Nitrogen 65wppm) used in present study

3LiFeNLiFeN2Li 233 3LiCrNLiCrN5Li 593

Effect of nitrogen on corrosion in Li

25

Experimental results (Transient of metal impurity in Pb-17Li)

0

2

4

6

8

10

12

0 500 1000 1500 2000 2500 3000 3500

FeCrWMn

Time (hours)

Con

cent

ratio

n (w

ppm

)

[1] M. G. Barker, P. Hubberstey, A. T. Dadd, S. A. Frankham, J. Nucl Mater., 114, 143-149 (1983). [2]V. Tsisar, M. Kondo, et al., J. Nucl. Mater, under review. H. U. Borgstedt, H. Feuerstein, J. Nucl. Mater., 191-194, 988-991. [3]N. Simon et al., Int. J. Heat Mass Transfer., vol.38, No.16, 3085-3090 (1995).

After the immersion of JLF-1 in Pb-Li.