Pd-W bimetallic systems: erosion behavior and hydrogen permeability
Erosion and hydrogen behavior are examined in the dense and high porous W-films on Pd. The obtained results are discussed from the viewpoint of plasma facing diffusion system creation for hydrogen isotope recycling control or tritium extraction.
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| Zitieren: | Pd-W bimetallic systems: erosion behavior and hydrogen permeability / G.P. Glazunov, A.A. Andreev, D.I. Baron, M.N. Bondarenko, R.A. Causey, A.M. Hassanein, A.L. Konotopskiy, A.P. Patokin, I.M. Neklyudov, N.D. Rybal’chenko, I.K. Tarasov, E.D. Volkov // Вопросы атомной науки и техники. — 2006. — № 6. — С. 77-79. — Бібліогр.: 3 назв. — англ. |
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Glazunov, G.P. Andreev, A.A. Baron, D.I. Bondarenko, M.N. Causey, R.A. Hassanein, A.M. Konotopskiy, A.L. Patokin, A.P. Neklyudov, I.M. Rybal’chenko, N.D. Tarasov, I.K. Volkov, E.D. 2015-05-20T16:22:41Z 2015-05-20T16:22:41Z 2006 Pd-W bimetallic systems: erosion behavior and hydrogen permeability / G.P. Glazunov, A.A. Andreev, D.I. Baron, M.N. Bondarenko, R.A. Causey, A.M. Hassanein, A.L. Konotopskiy, A.P. Patokin, I.M. Neklyudov, N.D. Rybal’chenko, I.K. Tarasov, E.D. Volkov // Вопросы атомной науки и техники. — 2006. — № 6. — С. 77-79. — Бібліогр.: 3 назв. — англ. 1562-6016 PACS: 52.40.Hf, 79.20.R https://nasplib.isofts.kiev.ua/handle/123456789/81787 Erosion and hydrogen behavior are examined in the dense and high porous W-films on Pd. The obtained results are discussed from the viewpoint of plasma facing diffusion system creation for hydrogen isotope recycling control or tritium extraction. This work was supported by the Science and Technology Center in Ukraine (STCU), project # 3134. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники ITER and fusion reactor aspects Pd-W bimetallic systems: erosion behavior and hydrogen permeability Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| title |
Pd-W bimetallic systems: erosion behavior and hydrogen permeability |
| spellingShingle |
Pd-W bimetallic systems: erosion behavior and hydrogen permeability Glazunov, G.P. Andreev, A.A. Baron, D.I. Bondarenko, M.N. Causey, R.A. Hassanein, A.M. Konotopskiy, A.L. Patokin, A.P. Neklyudov, I.M. Rybal’chenko, N.D. Tarasov, I.K. Volkov, E.D. ITER and fusion reactor aspects |
| title_short |
Pd-W bimetallic systems: erosion behavior and hydrogen permeability |
| title_full |
Pd-W bimetallic systems: erosion behavior and hydrogen permeability |
| title_fullStr |
Pd-W bimetallic systems: erosion behavior and hydrogen permeability |
| title_full_unstemmed |
Pd-W bimetallic systems: erosion behavior and hydrogen permeability |
| title_sort |
pd-w bimetallic systems: erosion behavior and hydrogen permeability |
| author |
Glazunov, G.P. Andreev, A.A. Baron, D.I. Bondarenko, M.N. Causey, R.A. Hassanein, A.M. Konotopskiy, A.L. Patokin, A.P. Neklyudov, I.M. Rybal’chenko, N.D. Tarasov, I.K. Volkov, E.D. |
| author_facet |
Glazunov, G.P. Andreev, A.A. Baron, D.I. Bondarenko, M.N. Causey, R.A. Hassanein, A.M. Konotopskiy, A.L. Patokin, A.P. Neklyudov, I.M. Rybal’chenko, N.D. Tarasov, I.K. Volkov, E.D. |
| topic |
ITER and fusion reactor aspects |
| topic_facet |
ITER and fusion reactor aspects |
| publishDate |
2006 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| description |
Erosion and hydrogen behavior are examined in the dense and high porous W-films on Pd. The obtained results are
discussed from the viewpoint of plasma facing diffusion system creation for hydrogen isotope recycling control or
tritium extraction.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/81787 |
| citation_txt |
Pd-W bimetallic systems: erosion behavior and hydrogen permeability / G.P. Glazunov, A.A. Andreev, D.I. Baron, M.N. Bondarenko, R.A. Causey, A.M. Hassanein, A.L. Konotopskiy, A.P. Patokin, I.M. Neklyudov, N.D. Rybal’chenko, I.K. Tarasov, E.D. Volkov // Вопросы атомной науки и техники. — 2006. — № 6. — С. 77-79. — Бібліогр.: 3 назв. — англ. |
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| fulltext |
Problems of Atomic Science and Technology. 2006, 6. Series: Plasma Physics (12), p. 77-79 77
Interface layer
PD-W BIMETALLIC SYSTEMS: EROSION BEHAVIOR
AND HYDROGEN PERMEABILITY
G.P. Glazunov 1, A.A. Andreev 1, D.I. Baron 1, M.N. Bondarenko 1, R.A. Causey 2,
A.M. Hassanein 3, A.L. Konotopskiy 1, A.P. Patokin,
I.M. Neklyudov 1, N.D. Rybal’chenko 1, I.K. Tarasov 1, E.D. Volkov 1
1 National Science Center “Kharkov Institute of Physics and Technology”,
Akademicheskaya Str.1, 61108, Kharkov, Ukraine;
2 Sandia National Laboratories, Livermore, CA 94550, USA;
3 Argonne National Laboratory, 60439 Argonne, IL, USA
Erosion and hydrogen behavior are examined in the dense and high porous W-films on Pd. The obtained results are
discussed from the viewpoint of plasma facing diffusion system creation for hydrogen isotope recycling control or
tritium extraction.
PACS: 52.40.Hf, 79.20.R
1. INTRODUCTION
To create the effective plasma facing W-Pd diffusion
systems for hydrogen recycling control and possible
tritium extraction, it was necessary to increase as much as
possible the hydrogen permeability of erosion resistant
W-layer of such two-layer diffusion systems.
One of the ways for this is the use of very porous W.
So in this work the technology was developed to produce
Pd-W systems with high porous tungsten coatings, and
the investigations of erosion behavior and hydrogen
permeability of such systems were carried out.
2. EXPERIMENTAL AND RESULTS
The experimental setup used in the erosion
experiments was the device DSM-1 [1] with steady state
mirror Penning discharge, which was ignited at magnetic
field 0.05 T and at work gas pressure about 0.2 Pa.
Plasma characteristics measurements with help of
multigrid and single Langmuir probes (central and
peripheral discharge regions, accordingly) have shown
that nitrogen ion energy for maximum of distribution
function are about 0.8 U for the whole range of discharge
voltage U from 0.6 keV to 2 keV. The samples for
studies (surface morphology and structure are shown in
Figures 1 and 2) were W films vacuum-plasma deposited
(VPD) or chemical vapor deposited (VPD) on
palladium/nickel foils of 20...25 mm diameter (for erosion
experiments) or on the 99.98 % pure Pd tubes of 6 mm
diameter, 0.25 mm thickness and 190 mm length (for
permeation studies). Porosity of VPD tungsten coatings
was changed over the range from 1...3 % to 45 %. The
last was produced in argon atmosphere at the pressure of
more than 10 Pa. Only dense CVD W-coatings were used,
as the impurity concentration in coatings strongly
increased at the regime of porous CVD W-film
producing.
Erosion coefficient values were measured by the
weight loss method reviewed in details in [1]. It is seen in
Figures 3-5 that erosion rate of porous tungsten films is
similar to that for dense VPD/CVD tungsten films and
that W erosion rate weakly depends on hydrogen
admixture to nitrogen up to 40...50 % concentration.
a b c
Fig. 1. The metallographic microscopic sections: a) after
and b) before etching;
(c) surface morphology of 15µm VPD W film deposited
at Ar pressure of 10.4 Pa
a b c
d e
Fig.2. Surface morphology ( 6000) of CVD W-films
deposited at the pressure of 2.6 Pa and at the temperatures:
a) 673 , b) 773 , c) 1073 , and microstructures
1000) of the ones deposited at the temperatures:
d) 773 , e) 1073
The scheme and methods of hydrogen permeation
experiments were similar to the used in the previous works
[2]. The dependencies of specific hydrogen flow (permeation
rate) j through Pd membrane with VPD W-films on inlet
hydrogen pressure p and on membrane temperature T are
shown in Fig. 6 and Fig. 7. The similar dependencies have
been measured for CVD W-Pd systems. From the data of
temperature dependencies of hydrogen permeation (Fig.7),
the activation energy values E of hydrogen permeability
were calculated to be for two-layer Pd-W systems with high
tungsten porosity E = 15.44 kJ/mol (for 9 µm and 14 µm
W film thickness).
2µm 20 µm 20 µm
W
78
0.01
0.1
1
0.5 1 1.5 2 2.5
Discharge voltage [kV]
Er
os
io
n
co
ef
fic
ie
nt
[a
t./
io
n]
Fig. 3. Erosion coefficient dependence on nitrogen ion
energy for Pd-W systems: - denseVPD W film,
– VPD W film of the 45% porosity, ó - experimental
data for hydrogen saturated W films [2]
0.01
0.1
1
0.7 1.2 1.7 2.2
Discharge voltage [kV]
Er
os
io
n
co
ef
fic
ie
nt
[a
t./
io
n]
Fig.4.CVD W-coating erosion coefficient energy
dependencies for different ions: Ar+(o),
N+(r),He+(ó),H+( )
0.001
0.01
0.1
1
0 20 40 60 80 100
Nitrogen concentration in H2-N2
mixture [% atom.]
Er
os
io
n
co
ef
fic
ie
nt
[a
t/i
on
]
calculation
experiment
Fig.5. Tungsten erosion coefficient versus nitrogen
concentration in hydrogen: experimental data for 1.2 keV
ion irradiation ( ), curve is the calculated data
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0 100 200 300 400
Hydrogen pressure [Pa 0 .5]
H
yd
ro
ge
n
pe
rm
ea
tio
n
ra
te
[c
m
3 /s.
cm
2 ]
Fig. 6. Hydrogen permeation rate at 973K temperature
versus pressure: bare palladium (o); high porous 14 µm
and 9 µm VPD W film on Pd ( , ö, ); 4 µm dense VPD W
film on Pd (r)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
0.9 1.4 1.9
Inverse temperature 1000/T [ K-1 ]
Ln
j
[ c
m
3 /s.
cm
2 ]
Fig. 7. Temperature dependencies of specific hydrogen flow
through two-layer Pd-W systems at 105 Pa H2 pressure: bare
palladium (o); high porous 14 µm and 9 µm W film on Pd
( ,ö); 4 µm dense W film on Pd (r)
This value of activation energy is higher that for bare
palladium (11 kJ/mol) and higher than for dense
VPD/CVD W-films (11...13 kJ/mol). But, in any case, the
values of activation energy of hydrogen permeation
through W-Pd bimetallic systems are much lower than the
one (131.67 kJ/mol) for the bulk W under gas-driven
permeation experiments reviewed in [3].
3. DISCUSSION
The absence of an influence of W porosity on its
erosion behavior (Fig. 3) is very encouraging result for
creation of plasma facing diffusion system. To explain
such erosion behavior one can to suppose the strong
influence of redeposition processes, when large number of
sputtered tungsten atoms deposits on nearest surfaces of
W film pores.
It is seen in Fig. 5, that the sputtering weakly depends
on hydrogen admixture to nitrogen up to the 40%
concentration. Such dependence can be easily explained
on the base of mass dependence of erosion rate, according
to equation [1]: α = α(H+)⋅IH/I + α(N+)⋅IN/I, where α(H+)
and α(N+) are the erosion coefficients under hydrogen and
nitrogen ion bombardment, respectively; I is the total ion
current; IH and IN are hydrogen and nitrogen ion currents,
respectively. So, hydrogen addition to the main working
gas (nitrogen) could not be the reason of the reported in
[2] and above mentioned effect of an erosion coefficient
decrease for hydrogen saturated W. And the suggested in
[2] physical mechanism to explain this effect is, most
likely, hydrogen selective sputtering.
Hydrogen permeation flow through W-Pd
membranes is near to j(P) ~ P0.5 for both dense and porous
W-films (see Fig. 6). But the unusual film thickness
dependence of hydrogen flow is observed: hydrogen flow
through 14 µm tungsten layer is higher than through W
film of 9 µm thickness. Investigations of substrate-film
interface have shown that transition layer forms of W
solid solution in Pd in Pd-W samples produced at more
than 873 K (see Fig.1). The additional heating can change
transition layer state (width, composition, etc.) and can
lead to increase of its role in hydrogen permeation
process. The special investigations of the influence of
long time baking of W-films on hydrogen permeation rate
have shown its essential (up to one order of magnitude)
increase with baking time increase [Fig. 8]. The activation
energy values increase, too.
79
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
0 5 10 15 20
Time [hours]
H
yd
ro
ge
n
pe
rm
ea
tio
n
ra
te
[c
m
3 /s.
cm
2 ]
Fig.8. Hydrogen permeation rate measured at 973K
temperature and at hydrogen pressure of 105 Pa versus time
of baking at 973K temperature:o - 4 µm VPD W- film on
Pd,ö - 300 µm CVD W-film on Pd
So the diffusion in transition layer on the Pd-W
interface could be the limiting stage. If so, one can
explain high hydrogen permeation with film thickness and
heating time increase as “interface opening”.
If to analyze the results on Pd-W system erosion
behavior together with the data on hydrogen permeation,
it is came into clear that high porous tungsten films are
very convenient material for plasma facing diffusion
system creation. Being of high erosion resistant, such
films can provide high hydrogen flows through them.
These properties could be useful not only for hydrogen
recycling control but for tungsten erosion decrease and
tritium extraction in future fusion systems. The obtained
results allowed starting the creation of working model of
plasma facing diffusion system. In the nearest future such
system will be installed in the Uragan-3M stellarator in
order to test in the edge plasma conditions.
4. CONCLUSIONS
There was not observed the influence of porosity of W
films on their erosion behavior.
Hydrogen admixture to nitrogen (up to 40% atom.)
does not essentially influence on the W erosion rate. This
confirms the hydrogen selective sputtering as the main
physical mechanism explaining the early observed effect
of W erosion coefficient decrease in hydrogen saturated
Pd-W system.
Hydrogen permeation rate through Pd-W systems
with high-porous W-films and activation energy of
hydrogen permeability for such systems are higher than
for Pd-W two-layer systems with dense W coatings.
These results could be explained if to suppose the
diffusion in transition layer on the Pd-W interface as the
limiting stage of Pd-W two-layer system permeation
process.
ACKNOWLEDGEMENTS
This work was supported by the Science and
Technology Center in Ukraine (STCU), project # 3134.
REFERENCES
1. G. P. Glazunov et al. //Physica Scripta. 2003, v. T103,
p. 89-92.
2. G.P. Glazunov, et al., //Fusion Engineering and
Design. 2006, v. 81, 375.
3. W.G. Perkins. // J. Vac. Sci. Technol. 1973, v.10, N 4,
p. 543.
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