International Scientific-Technical and Production Journal
December
2011
# 12
English translation of the monthly «Avtomaticheskaya Svarka» (Automatic Welding) journal published in Russian since 1948
Editor-in-Chief B.E.Paton
Yu.S.Borisov V.F.Khorunov
A.Ya.Ishchenko I.V.Krivtsun
B.V.Khitrovskaya L.M.Lobanov
V.I.Kyrian A.A.Mazur
S.I.Kuchuk-Yatsenko
Yu.N.Lankin I.K.Pokhodnya
V.N.Lipodaev V.D.Poznyakov
V.I.Makhnenko K.A.Yushchenko
O.K.Nazarenko A.T.Zelnichenko
I.A.Ryabtsev
CONTENTS
SCIENTIFIC AND TECHNICAL
. and
. Formation of liquid metal film at the tip of
wire-anode in plasma-arc spraying .......................................... 2
. and
N.P.Alyoshin (Russia)
U.Diltey (Germany)
Guan Qiao (China)
D. von Hofe (Germany)
V.I.Lysak (Russia)
N.I.Nikiforov (Russia)
B.E.Paton (Ukraine)
Ya.Pilarczyk (Poland)
G.A.Turichin (Russia)
Zhang Yanmin (China)
A.S.Zubchenko (Russia)
V.N.Lipodaev, V.I.Lokteva
A.T.Zelnichenko (exec. director)
A.A.Fomin, O.S.Kurochko,
I.N.Kutianova, T.K.Vasilenko
N.A.Dmitrieva
D.I.Sereda, T.Yu.Snegiryova
. and
. Effect
of single-phase power sources of welding arc on
electric mains ......................................................................... 7
. Investigation of
thermochemical characteristics of mixtures of
dispersed materials by differential thermal analysis
methods ................................................................................. 13
. Control of properties of the weld metal by
regulating the level of oxidation of the weld pool in
gas-shielded welding .............................................................. 16
. Hygroscopicity of high-basicity
synthetic flux .......................................................................... 20
INDUSTRIAL
. and
.
Transformable structures (Review) .......................................... 25
. and
State Registration Certificate
KV 4790 of 09.01.2001
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© PWI, International Association «Welding», 2011
. Application of automatic
orbital welding to fabricate absorbing inserts for spent
nuclear fuel storage containers ............................................... 34
. and
. Two-layer
bio-cermet titanium—hydroxyapatite coating ............................. 38
. Organization and topics of R&D in
the field of joining technologies conducted by TWI and
DVS Association of Researchers (Review) ................................ 41
Index of articles for TPWJ’2011, Nos. 1—12 .............................. 45
List of authors ........................................................................ 49
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Стр.1
FORMATION OF LIQUID METAL FILM AT THE TIP
OF WIRE-ANODE IN PLASMA-ARC SPRAYING
M.Yu. KHARLAMOV1, I.V. KRIVTSUN2, V.N. KORZHIK2 and S.V. PETROV2
1V. Dal East-Ukrainian National University, Lugansk, Ukraine
2E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
A mathematical model is proposed, describing formation of a molten metal film at the tip of sprayed anode-wire under
the conditions of plasma-arc spraying of coatings. Numerical analysis of the influence of spraying mode parameters on
the position of molten wire tip relative to plasma jet axis, thickness of liquid interlayer contained on the wire tip,
temperature and velocity of metal flow in it was performed.
Keywords: plasma-arc
spraying,
coatings,
wire-anode,
spraying modes, thermal condition, molten metal film, mathematical
model
Stability of the process of plasma-arc wire spraying,
as well as formation of specified quality characteristics
of coatings, are largely determined by the conditions,
under which the concentrated flow of spraying material
particles is formed. Parameters of the formed dispersed
particles depend chiefly on the intensity of the
processes of thermal and gas-dynamic interaction of
melting wire-anode with arc plasma flow moving
around it. Therefore, detailed study of the above processes,
including development of
the
appropriate
mathematical models, is highly important for further
progress of plasma-arc spraying technology.
Spraying of wire consumables is not given enough
attention in scientific-technical
publications,
the
available work being devoted, mainly to the process
of electric-arc metallizing [1—3]. Results obtained in
the above studies are not applicable to the process of
plasma-arc spraying, as it differs by the location of
sprayed wire relative to the arc (the latter form an
angle of 70—90°), as well as high values of temperature
(up to 30,000 K) and velocity (up to 4000 m/s) of
plasma, flowing around the wire [4].
For the conditions of plasma-arc spraying a model
was earlier proposed for thermal processes in solid
metal wire-anode, fed into the plasma arc behind the
plasmatron nozzle tip [5]. This model allows forecasting
the temperature field and calculating the molten
metal volume depending on the parameters of plasmatron
operation mode, wire feed rate and diameter,
as well as its position in space relative to the tip of
plasma-shaping nozzle and distance from molten wire
tip to plasma jet axis. However, the melt zone thickness
obtained within this model can differ considerably
from that observed in the experiments. The reason
for that is the molten metal at the wire tip being under
a considerable dynamic impact of the plasma flow that
results in just part of the melt being contained at the
wire tip, forming a liquid interlayer, and part being
carried off into a thin jet – so-called tongue [1].
© M.Yu. KHARLAMOV, I.V. KRIVTSUN, V.N. KORZHIK and S.V. PETROV, 2011
2
Here, the molten wire tip takes up such a position
relative to plasma jet axis that corresponds to the
thickness of liquid interlayer, ensuring a balance of
thermal and dynamic impact of plasma on the molten
metal. In other words, for a correct determination of
the parameters of liquid metal interlayer contained on
the sprayed wire tip, as well as distance from the
molten wire tip to the plasma jet axis, it is necessary
to coordinate the calculations within the thermal
model [5] with calculations of gas-dynamic impact of
the transverse plasma flow on the molten metal. Development
of such a self-consistent model is exactly
the objective of this study.
When plotting a mathematical model of formation
of molten metal film at the tip of sprayed wire-anode
under the conditions of plasma-arc spraying, let us
assume that solid metal wire of round cross-section of
radius Rw is fed into the plasma arc at constant rate
vw normal to the axis of symmetry of the plasma flow
(Figure 1). The arc closes on the wire right end which
is the anode. Let us also assume that the melting front
is flat (plane zb = 0) and is located normal to the
plasma flow axis at distance Lp from it, and the rate
of wire melting is equal to its feed rate. Under the
impact of the arc anode spot and high-temperature
plasma flow moving around the arc, it is heated, and
molten metal volume of thickness Lliq forms at its tip,
that is carried off into a thin jet by plasma flow moving
around the arc. Let us assume that the upper part of
liquid interlayer contained at the wire tip takes the
form of a spherical segment under the impact of the
arriving plasma flow, the spherical segment having
height Lb and radius Rb of a sphere forming the segment
with the center in a point located at distance L0
from the melting front (Rb = L0 + Lb; Rb
2 = L0
2 + Rw
2 )
(see Figure 1).
As a result of removal of part of the melt from the
wire tip, the conditions of heat balance in it are violated.
Tending to an equilibrium condition, the wire
will take up such a position relative to plasma jet
axis, defined, for instance, by distance Lp — Lb, at
which the volume of liquid interlayer contained at the
12/2011
Стр.2