Plasma of electric arc between composite electrodes on silver base
The investigations of the processes of the mass transfer in a discharge gap of electric arc and peculiarity of interactions of discharge plasma with composite electrode surface were carried out. The optical spectroscopy and metallographic techniques were used. It was found that qualitative change of...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Cite this: | Plasma of electric arc between composite electrodes on silver base / I.L. Babich, V.F. Boretskij, L.A. Kryachko, R.V. Minakova, R.V. Semenyshyn, A.N. Veklich // Вопросы атомной науки и техники. — 2010. — № 6. — С. 141-143. — Бібліогр.: 5 назв. — англ. |
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Babich, I.L. Boretskij, V.F. Kryachko, L.A. Minakova, R.V. Semenyshyn, R.V. Veklich, A.N. 2011-02-26T22:21:44Z 2011-02-26T22:21:44Z 2010 Plasma of electric arc between composite electrodes on silver base / I.L. Babich, V.F. Boretskij, L.A. Kryachko, R.V. Minakova, R.V. Semenyshyn, A.N. Veklich // Вопросы атомной науки и техники. — 2010. — № 6. — С. 141-143. — Бібліогр.: 5 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/17484 The investigations of the processes of the mass transfer in a discharge gap of electric arc and peculiarity of interactions of discharge plasma with composite electrode surface were carried out. The optical spectroscopy and metallographic techniques were used. It was found that qualitative change of electric erosion mechanism of electrodes components are realized with increasing of arc current up to 30 A. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Низкотемпературная плазма и плазменные технологии Plasma of electric arc between composite electrodes on silver base Плазма электрической дуги между композиционными электродами на основе серебра Article published earlier |
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Plasma of electric arc between composite electrodes on silver base |
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Plasma of electric arc between composite electrodes on silver base Babich, I.L. Boretskij, V.F. Kryachko, L.A. Minakova, R.V. Semenyshyn, R.V. Veklich, A.N. Низкотемпературная плазма и плазменные технологии |
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Plasma of electric arc between composite electrodes on silver base |
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Plasma of electric arc between composite electrodes on silver base |
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Plasma of electric arc between composite electrodes on silver base |
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Plasma of electric arc between composite electrodes on silver base |
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plasma of electric arc between composite electrodes on silver base |
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Babich, I.L. Boretskij, V.F. Kryachko, L.A. Minakova, R.V. Semenyshyn, R.V. Veklich, A.N. |
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Babich, I.L. Boretskij, V.F. Kryachko, L.A. Minakova, R.V. Semenyshyn, R.V. Veklich, A.N. |
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Низкотемпературная плазма и плазменные технологии |
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Низкотемпературная плазма и плазменные технологии |
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2010 |
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English |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Плазма электрической дуги между композиционными электродами на основе серебра |
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The investigations of the processes of the mass transfer in a discharge gap of electric arc and peculiarity of interactions of discharge plasma with composite electrode surface were carried out. The optical spectroscopy and metallographic techniques were used. It was found that qualitative change of electric erosion mechanism of electrodes components are realized with increasing of arc current up to 30 A.
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1562-6016 |
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https://nasplib.isofts.kiev.ua/handle/123456789/17484 |
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Plasma of electric arc between composite electrodes on silver base / I.L. Babich, V.F. Boretskij, L.A. Kryachko, R.V. Minakova, R.V. Semenyshyn, A.N. Veklich // Вопросы атомной науки и техники. — 2010. — № 6. — С. 141-143. — Бібліогр.: 5 назв. — англ. |
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PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2010. 6. 141
Series: Plasma Physics (16), p. 141-143.
PLASMA OF ELECTRIC ARC BETWEEN COMPOSITE ELECTRODES
ON SILVER BASE
I.L. Babich1, V.F. Boretskij1, L.A. Kryachko2, R.V. Minakova2, R.V. Semenyshyn1, A.N. Veklich1
1Taras Shevchenko National University of Kiev, Kiev, Ukraine;
2 Institute of Materials Technology Problems NAS of Ukraine, Kiev, Ukraine
E-mail: van@univ.kiev.ua
The investigations of the processes of the mass transfer in a discharge gap of electric arc and peculiarity of
interactions of discharge plasma with composite electrode surface were carried out. The optical spectroscopy and
metallographic techniques were used. It was found that qualitative change of electric erosion mechanism of electrodes
components are realized with increasing of arc current up to 30 A.
PACS: 52.25.Os, 52.70.-m, 52.80.Mg
1. INTRODUCTION
Composite materials on a base of copper and silver are
widely used as electrode or contact materials in electric
industry applications (e.g. relays, commutators, circuit
breakers etc.) [1,2]. The principal contact materials on a
silver base are described and classified up today. In silver –
oxide of metal system oxides either of cadmium or stannum
either copper or zinc at mass concentrations in the range
from 8 to 20% are used. Such materials are obtained either
by powder metallurgy techniques or by an internal oxidation
of silver and cadmium (either stannum or copper) alloy.
Electro- and heat conductivities of such materials decrease
with increasing of oxide content. Materials of silver –
cadmium oxide system are characterized both by an
excellent erosion resistance and a significant welding
resistance as well as a least contact resistance in comparison
with other materials of silver – metal oxide system. As an
industrial application of cadmium leads to the environmental
pollution the more regard must be paid to the development of
those materials, which contain alternate materials, in
particular, Ag–CuO or Ag–SnO2.
The operation efficiency of switching devices is defined
by the intensity of mass transfer processes in a discharge gap.
Obviously such processes are depended both on the surface
structure of electrodes (contacts) and plasma parameters of
an arc discharge as well. The composition optimization of an
appropriate composite material requires the detail metallo-
graphic investigations of such electrodes surface and plasma
parameters in a discharge gap too. Naturally, silver is a main
component in a composite system of silver – metal oxide.
Most probably parameters of electrodes surface as well as
arc discharge plasma are determined just by this element.
There are an insignificant number of experimental and
theoretical papers, which deal with an investigation of
surface condition, plasma parameters and arc discharge
between single-component silver electrodes in the up-to-date
literature. Unfortunately there are no complex investigations
both surface and plasma parameters of arc discharge between
composite electrodes on silver base in a literature as well.
The probable reason is “the inconvenience” of silver atom in
spectroscopy investigations, in particular in optical emission
spectroscopy. The matter is that spectral lines of this
element, which wave lengths are located in preferable from
the point of view of diagnostics visible range, correspond to
transitions from closely spaced upper levels. This leads to the
low accuracy of a plasma temperature determination in
particular. The additional problem is a large variety of
available in a nowadays literature spectroscopic data for
these lines (transition probability, oscillator strength etc.).
The main aim of this paper is a complex investigation
both surface and plasma parameters of arc discharge between
fabricated by a powder metallurgy technique composite
electrodes Ag–CuO (90/10).
2. EXPERIMENT
The arc was ignited in air between the end surfaces of the
non-cooled electrodes. The diameter of the rod electrodes
was 6 mm, the discharge gap was 8mm, and the arc current
was 3.5 and 30 A. To avoid the metal droplet appearing a
pulsing high current mode was used: the current pulse 30 A
was put on the "duty" weak-current (3.5A) discharge. The
pulse duration ranged up to 30 ms.
The spatial distribution of metal vapours in a
discharge gap we measured by techniques of optical
emission spectroscopy (OES) [3-5] and laser absorption
spectroscopy (LAS) [3,4] as well.
The structural changes in the working layer of electrodes
were investigated by the optical microscope "Neophot-2"
and the scanning electron microscope (SEM) with the X-ray
microanalyzer "JSM Super Probe-733", JEOL.
3. RESULTS AND DISCUSSIONS
3.1. MASS TRANSFER IN A DISCHARGE GAP
Two independent spectroscopy techniques in a study of
the spatial distribution of metal vapours were used. In OES
the temperature profiles T(r) in electric arc between
composite electrodes were obtained from relative intensities
of spectral lines AgI 405.5 and 768.8 nm as well as by the
Boltzmann plot techniques. In the last case intensities of
spectral lines AgI 405.5; 447.6; 466.8; 520.9; 546.5; 547.2;
768.8; 827.4 nm and CuI 427.5; 465.1; 510.5; 515.3; 521.8;
570.0; 578.2; 793.3; 809.3 nm were used. Spectroscopic data
of these spectral lines were carefully analyzed and examined.
The radial profiles of electron densities Ne(r) in discharge at
30 A are obtained from width of spectral lines CuI 448.0;
515.3 nm and AgI 447.6; 466.8 nm in a case of prevail quad-
ratic Stark broadening. The ratio of atom concentrations AgI
and CuI in plasma was calculated from radial profiles of in-
tensities of spectral lines AgI 405.5 and CuI 465.1 nm in the
assumption of the equilibrium of the energy level population.
The obtained electron density and the temperature in
plasma as initial parameters were used in the calculation
of the plasma composition in the local thermal equilibrium
(LTE) assumption. So, it can be possible to calculate the
concentration of any considered plasma particle in a
discharge gap and the content of silver and copper
vapours as well.
mailto:van@univ.kiev.ua
142
In Fig. 1 the radial distributions of content of silver and
copper vapours in discharge gap between composite
Ag-CuO electrodes at arc currents 3.5 (a) and 30 A (b) are
shown. Such content of metals in plasma is determined
traditionally as XAg, % = (NAg+NAg+)·100/∑Nj and
XCu, % = (NCu+NCu+)· 100/∑Nj.
0 1 2
1E-5
1E-4
1E-3
0,01
r, mm
Xj, %
XAg
XCu
a
0 1 2 3
1E-5
1E-4
1E-3
0,01
r, mm
Xj, %
XAg
XCu
b
Fig. 1. Radial profiles of content of silver and copper
vapours in discharge between composite Ag–CuO
electrodes at arc currents 3.5 A (a) and 30 A (b)
One can conclude that silver content in plasma is more
than copper content by a factor of 12 at discharge current
3.5 A. The value of this factor is 7 with current increasing up
to 30 A. Obviously it means that mechanism of electric
erosion of electrode components is changed.
One another technique of copper vapours visualization is
LAS.
The absorption coefficient at the centre of the spectral
line CuI 510.5 nm in arc plasma volume was measured [3].
From this coefficient of absorption it is possible to calculate
the population of the lower level of such spectral transition.
So, in this manner we could realize the visualization of
copper vapours in a discharge gap at least. Moreover, we can
be able to calculate the spatial distribution of copper atom
concentration NCu in the assumption of the equilibrium of the
energy level population.
In Fig. 2 the radial distributions of NCu in discharge gap
between composite Ag–CuO electrodes obtained by optical
emission and laser absorption spectroscopy at arc currents
3.5 and 30 A are shown.
As one can see the concentration of copper atom is
naturally raised with increasing discharge current. Good
agreement is observed with values obtained by different
techniques. There is one more conclusion can be made in this
case. Namely, it means that investigated plasma in
considered arc discharge modes can be properly described
within model of LTE.
0 1 2 3
1E12
1E13
1E14
1
2
3
4
r, mm
NCu, cm-3
Fig.2. Radial distributions of copper atom concentration in
discharge gap between composite Ag–CuO electrodes
obtained by OES (1,3) and LAS (2,4) spectroscopy at arc
currents 3.5 A (1,2) and 30 A (3, 4)
To clarify the efficiency of the mass transfer processes in
a discharge gap and peculiarity of interactions of electrode
surface with arc plasma we carried out additional surface
investigations by metallographic technique.
3.2. PLASMA-SURFACE INTERACTIONS
The structural changes in a working layer of electrode
were studied by metallographic analysis of microvolumes
of a working layer.
Usually, such secondary modified surface of
composite electrode has a complicated unique structure in
air arc discharges [3].
The carried out analysis testified that the electrical
erosion of Ag–CuO electrodes under influence of the free
burning in air electric arc occurs mainly in a vapour phase
at discharge current of 3.5 A. Both silver and copper as
well are evaporated in accordance with their
stoichiometric relationships in the electrode composition
in this mode of arc operation. The quantitative
confirmation of such mechanism of metals evaporation
one can observe in Fig.1, a.
It was found as well that the electric erosion increases
with increasing current up to 30A. But the condition of
silver and copper evaporation is changed at once.
In Fig. 3 the secondary structure on the surface of
electrode treated by 5 single 30 A pulses of current (the
duration of each is 30 ms) is shown. Fragments of normal
surface section in silver and copper X-rays are shown too
(see Fig. 3, d, e).
The segregation of silver and copper component in the
working layer is clearly observed in this mode of arc
operation. It led to the different kind of evaporation
mechanism of silver and copper components. It was found
that the electrical erosion of Ag-CuO electrodes under
influence of the free burning in air electric arc can be in
addition realized in a solid phase too at discharge current
of 30 A. Therefore, it is not surprising that silver/copper
ratio in plasma in the discharge gap is changed.
143
a b
d e
Fig. 3. The normal surface section of working layer of composite Ag–CuO anode treated by arc current of 30 A
4. CONCLUSIONS
It was found, that the current increasing up to 30 A
causes the metals content increasing by factor 10 in
plasma in discharge gap between composition Ag–CuO
electrodes. The ratio of silver/copper in plasma in the
discharge gap is decreased in this mode of arc operation.
The metallographic investigations confirmed that with
increasing of the input power into discharge the
qualitative electrodes surface modifications are realized
which are caused by change of electric erosion
mechanism of each component.
REFERENCES
1. R.V. Minakova, A.P. Kresanova, M.M. Churakov,
E.V. Khomenko. The development tendencies of
manufacturing technologies of composite materials and
their contacts // Electric Contacts and Electrodes. Kiev:
“IPM NANU”, 1998, p. 5-19 (in Russian).
2. G.V. Butkevich, G.S. Belkin, et al. Erosion of electric
contacts and electrodes. Moscow: ”Energia”, 1978.
3. I.L. Babich, D.V. Chukhalenko, N.I. Grechanyuk, et al.
Plasma of electric arc discharge between Cu-Mo
electrodes // Problems of Atomic Science and
Technology. Series “Plasma Physics” (11). 2007, N 1,
p. 139-141.
4. I.L. Babich, V.F. Boretskij, A.N. Veklich. Plasma of
electric arc discharge between copper electrodes //
Contr. papers of the XVIIth Symp. on Phys. of Switching
Arc (FSO 2007). Brno, 10-13 Sept., 2007 / Univ. of
Techn., Brno. , 2007, v. I, p. 13-16.
5. I.L. Babich, A.N. Veklich, V.Ye. Osidach.
Investigation of the electric arc discharge plasma
between composition electrodes on the copper base
//Bull. of the Univ. of Kiev. Series “Phys.&Math.”
2006, N 4, p. 265-268.
Article received 13.09.10
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